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RG-6 for HF?
I finally got a house out in the woods on five acres and I'm going to set up
a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian |
RG-6 for HF?
On Sun, 30 Dec 2007 22:45:38 -0500, "Brian"
wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian Go with the RG-6, the loss at HF is negligable - in fact I believe less than RG-58 and perhaps RG-8 as well. The 'mismatch' isn't an issue at all & your receiver will likely never know it either. If you are putting together the antenna yourself I suggest using a panel mount 'F' connector at your feed point, use the coax as-is from the box - though I cheat at the radio end and use an 'F' to UHF adapter. |
RG-6 for HF?
Brian wrote:
I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian Belden 9258 is not cheap. |
RG6 Coax Cable and Mounting a Wellbrook Loop Antenna [Was : RG-6 forHF]
On Dec 30, 7:45*pm, "Brian" wrote:
- - I finally got a house out in the woods on five acres and - I'm going to set up a couple of pretty long wires and my - Wellbrook ALA-1530. I've pretty much decided on RG-6 - for a couple of 150 ft. runs because the stuff's dirt cheap - and I can pick it up at the local Home Depot. - - Is the impedance mismatch here going to be negligible, - or should I just bite the bullet and go with RG-8 or a - similar 50 ohm coax? - - -Brian - Brian, RG6 Coax Cable will work A-OK with only the smallest of Impedance Mismatches over RG58 or RG8. Consider the 'Quad-Shield' type of the RG6 Coax Cable. # 1 - Search around your Backyard for an RF 'Quiet' Location before Planting your Wellbrook Antenna. :o) Mount the Wellbrook Loop Antenna where you can : the best that you can for your Property and Location. Place a Ground Rod at the base of the Wellbrook Loop Antenna. Mount an F-Connector Pass-Through type Grounding Block on the Ground Rod and Run a short Coax Cable down to this Grounding Block; and then your main {long} Coax Cable from the Grounding Block to you House. If you can : Bury the Coax Cable from the Grounding Block to the House. You should have a good in-the-earth 8-Foot Ground Rod as the basis for you Radio Shack's Ground that is Bonded {Connected} to your House's AC Mains Electrical System Ground. TIP - For Active Shortwave Listener's Antennas like the Wellbrook Loop Antenna and many others : A One-Piece Antenna Mast made from a single piece of 21-Foot Long Top-Rail works very well. * One Piece of Metal Pipe-Tube with a Solid Electrical Path. * Relatively Light and Easy to Handle by One Person. * Three Feet in the Ground leaves 18-Feet in the Air. * Base can be Telescoped into a Larger Diameter 3-Feet piece of Metal Pipe-Tube which is placed in an 6~8 Inch Hole and surrounded by Concret that is used as a Support Anchor for the Top-Rail and Antenna. * Allows for a Free Standing Antenna without the need for any Guy Wires or Ropes * Place the Ground Rod within 3~6 Inches of the Top-Rail and connect a Short-Heavy Ground Wire-Strap-Web between them. the Result is that you have a Solid One-Piece Ground Active Antenna Support that places your Antenna 18-Feet Up-in-the-Air. good luck with your wellbrook loop antenna ~ RHF |
Using Two Inverted "L" Antennas as Diversity Antennas [Was : RG-6 forHF?]
On Dec 30, 7:45*pm, "Brian" wrote:
- - I finally got a house out in the woods on five acres and - I'm going to set up a couple of pretty long wires - - and my Wellbrook ALA-1530. I've pretty much decided - on RG-6 for a couple of 150 ft. runs because the stuff's - dirt cheap and I can pick it up at the local Home Depot. - - Is the impedance mismatch here going to be negligible, - or should I just bite the bullet and go with RG-8 or a - similar 50 ohm coax? - - -Brian - Brian, For the Longwire Antennas {Random Wire} consider the Inverted "L" Antenna. READ - For Basic Shortwave Radio Listening (SWL) -Think- Inverted "L" Antenna http://www.google.com/group/rec.radi...0a3255b9ad5367 READ -Why- The Far-End-Fed Shortwave Listener's (SWLs) Inverted "L" Antenna http://www.google.com/group/rec.radi...cfc6b9cb2447c0 http://groups.yahoo.com/group/Shortw.../message/11698 Re-READ - SWL Longwire + Low Noise Antenna Connection + Grounding Is Key To Good Reception -by- John Doty http://www.google.com/group/rec.radi...bc6a2bf8acc12d Two separate but identical Inverted "L" Antennas both with 15~30 Foot Vertical-Up-Legs and 75~120 Foot Horizontal-Out-Arms. Located with the Antenna Feed-Points about 75~120 Feet apart and use a separate Ground Rod for each Antenna. Position the Horizontal-Out-Arm Wire Antenna Elements so that they are Perpendicular 90 Degrees to each other : N2S and E2W Think of the Two Inverted "L" Antennas as Diversity Antennas Being Both : Opposites -but- Equal. good luck with your longwire antennas ~ RHF {pomkia} |
RG-6 for HF?
Brian wrote:
I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. snip Be careful of coax purchases from Home Depot; strip the outer jacket and inspect the braid before buying. Product that I have bought has lousy shielding at low vhf (50 Mhz) and probably will be unsuitable at HF as well. I don't remember the OEM. Regards, Michael |
RG-6 for HF?
In article ,
"Brian" wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? I would not buy cable with the wrong impedance especially on the Wellbrook because I don't know how well the amplifier at the head end stands up to reflections. Some amplifiers become less stable into a load other than what it was designed for. Why don't you fire off that question to them. On the wire antennas you will take a hit on performance depending on frequency unless you use transformers on both ends. -- Telamon Ventura, California |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 CoaxCable
On Dec 30, 9:37*pm, D Peter Maus wrote:
Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - - * *As a complex, however, you're going to have not one mismatch, but - two. One at the output of the Wellbrook loop, and one at the input of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - * *With a reasonably well designed receiver, you'll likely not notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF |
RG6 Coax Cable and Mounting a Wellbrook Loop Antenna [Was : RG-6for HF]
RHF wrote:
On Dec 30, 7:45 pm, "Brian" wrote: - - I finally got a house out in the woods on five acres and - I'm going to set up a couple of pretty long wires and my - Wellbrook ALA-1530. I've pretty much decided on RG-6 - for a couple of 150 ft. runs because the stuff's dirt cheap - and I can pick it up at the local Home Depot. - - Is the impedance mismatch here going to be negligible, - or should I just bite the bullet and go with RG-8 or a - similar 50 ohm coax? - - -Brian - Brian, RG6 Coax Cable will work A-OK with only the smallest of Impedance Mismatches over RG58 or RG8. Consider the 'Quad-Shield' type of the RG6 Coax Cable. # 1 - Search around your Backyard for an RF 'Quiet' Location before Planting your Wellbrook Antenna. :o) Mount the Wellbrook Loop Antenna where you can : the best that you can for your Property and Location. Place a Ground Rod at the base of the Wellbrook Loop Antenna. Mount an F-Connector Pass-Through type Grounding Block on the Ground Rod and Run a short Coax Cable down to this Grounding Block; and then your main {long} Coax Cable from the Grounding Block to you House. If you can : Bury the Coax Cable from the Grounding Block to the House. You should have a good in-the-earth 8-Foot Ground Rod as the basis for you Radio Shack's Ground that is Bonded {Connected} to your House's AC Mains Electrical System Ground. TIP - For Active Shortwave Listener's Antennas like the Wellbrook Loop Antenna and many others : A One-Piece Antenna Mast made from a single piece of 21-Foot Long Top-Rail works very well. * One Piece of Metal Pipe-Tube with a Solid Electrical Path. * Relatively Light and Easy to Handle by One Person. * Three Feet in the Ground leaves 18-Feet in the Air. * Base can be Telescoped into a Larger Diameter 3-Feet piece of Metal Pipe-Tube which is placed in an 6~8 Inch Hole and surrounded by Concret that is used as a Support Anchor for the Top-Rail and Antenna. * Allows for a Free Standing Antenna without the need for any Guy Wires or Ropes * Place the Ground Rod within 3~6 Inches of the Top-Rail and connect a Short-Heavy Ground Wire-Strap-Web between them. the Result is that you have a Solid One-Piece Ground Active Antenna Support that places your Antenna 18-Feet Up-in-the-Air. good luck with your wellbrook loop antenna ~ RHF . Around here the top rail comes in 10' sections. Ever try to get a 20' pipe into a pickup bed? |
Using Two Inverted "L" Antennas as Diversity Antennas [Was :RG-6 for HF?]
RHF wrote:
. | | | / \ .......!....... I have a lazy twisted L HF receive antenna. |
RG-6 for HF?
msg wrote:
Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. snip Be careful of coax purchases from Home Depot; strip the outer jacket and inspect the braid before buying. Product that I have bought has lousy shielding at low vhf (50 Mhz) and probably will be unsuitable at HF as well. I don't remember the OEM. Regards, Michael Use satellite rated quad shield. |
RG-6 for HF?
Telamon wrote:
In article , "Brian" wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? I would not buy cable with the wrong impedance especially on the Wellbrook because I don't know how well the amplifier at the head end stands up to reflections. Some amplifiers become less stable into a load other than what it was designed for. Why don't you fire off that question to them. On the wire antennas you will take a hit on performance depending on frequency unless you use transformers on both ends. I'd give it a try. I doubt modern active devices will have any trouble with such a small difference. |
What Does "RG-6" {Coax Cable} Mean ?
On Dec 30, 9:44*pm, msg wrote:
Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. snip - - Be careful of coax purchases from Home Depot; - strip the outer jacket and inspect the braid before buying. -*Product that I have bought has lousy shielding at low vhf - (50 Mhz) and probably will be unsuitable at HF as well. -*I don't remember the OEM. - - Regards, - - Michael - MSG, Yes the 'quality' of Coax Cable does vary. http://en.wikipedia.org/wiki/Coaxial_cable http://en.wikipedia.org/wiki/Coaxial_cable#Standards Especially when you buy 'Generic' Stuff at a BigBox {Discount} Retailer at a Low Price. Usually Quad-Shield RG6 {75 Ohm} Coax Cable is fairly good stuff. http://en.wikipedia.org/wiki/RG-6 http://www.hometech.com/techwire/coax.html#HT-RG6QB http://www.hometech.com/techwire/coax.html#BE-1189A http://www.hometech.com/techwire/coax.html#BE-7916A * Two Aluminium Braid Shields 60% and 40% * Two AL Foil 100% Shields * Gas-Injected (Foamed) PE Dielectric * Inner Conductor : Solid Copper or Copper-Clad-Steel PVC Outer Jacket {Cover} http://cableorganizer.com/coaxial-ca...oax-cable.html http://www.homenetworkgear.com/catal...6F 8&pid=1207 Genesis* 1000 Feet Bulk RG-6 Quad Shield Coaxial Cable http://cgi.ebay.com/_W0QQitemZ130139914168 * Genesis Premium Broadband Cable, Manufactured by Honeywell What Does "RG-6" {Coax Cable} Mean ? http://www.bluejeanscable.com/articles/rg6.htm -presented by- Blue Jeans Cable Note - Home Depot only lists one RG6 Coax Cable OnLine. http://tinyurl.com/3y97cq Brand 'BICC' 500 Ft. Black RG6 Quad-Shield Coaxial Cable Model 92041-45-08 - Cable Type : RG6/U Impedance Ohms : 75 Ohms Nominal O.D. : 0.307 In. Wire Gauge/Number of Conductors : 1/18 AWG Cable Length : 500 Ft. Suitable for LAN, cable, digital video, and direct broadcast satellite. Sunlight Resistant - Coaxial Cable Home Depot - http://www.homedepot.com/ CAUTION - The big problem with RG6 Coax Cable and even the Quad-Shield type is the Aluminium Braid is not as good a Conductor as Copper Braid. TIP - You may have to run a Heavy Copper Wire along with the RG6 Coax Cable to "Bond" your Antenna Ground with your House's AC Mains Ground. Be Advised - None of the above RG6 Coax Cable is 'designated' for Direct Burial. you got to be 'wired' to listen to the radio - iane ~ RHF {pomkia} |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 CoaxCable
On Dec 31, 7:21*am, BDK wrote:
In article 43a532e0-63d5-4ae1-b27a-72085c8bbbf8 @t1g2000pra.googlegroups.com, says... On Dec 30, 9:37*pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - *Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - - * *As a complex, however, you're going to have not one mismatch, but - two. One at the output of the Wellbrook loop, and one at the input of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - * *With a reasonably well designed receiver, you'll likely not notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." - - IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) - - Practical Implementation Says : Just Do It ! - Use the RG6 Coax - - Cable -and- enjoy listening to your radios - iane ~ RHF - - *. - Why bother with all that? I've used RG6 coax for decades without - any issues. A 1.5 to 1 SWR is nothing to worry about at all. - - This is just being anal. - - BDK - BDK - That I Am, and . . . Retentive Too ! ~ RHF http://en.wikipedia.org/wiki/Anal_retentive -butt- Then Again I Did Also Write : IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF |
What Does "RG-6" {Coax Cable} Mean ?
RHF wrote:
snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael |
What Does "RG-6" {Coax Cable} Mean ?
On Dec 31, 9:17*am, msg wrote:
RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. *In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6Coax Cable
RHF wrote:
On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - - As a complex, however, you're going to have not one mismatch, but - two. One at the output of the Wellbrook loop, and one at the input of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 CoaxCable
On Dec 31, 10:06*am, D Peter Maus wrote:
RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - *Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - - * *As a complex, however, you're going to have not one mismatch, but - two. One at the output of the Wellbrook loop, and one at the input of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - * *With a reasonably well designed receiver, you'll likely not notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver - - - won't care. I doubt that the Wellbrook would, either." - - - - IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) - - Practical Implementation Says : Just Do It ! - Use the RG6 Coax - - Cable -and- enjoy listening to your radios - iane ~ RHF - - *. - Which was precisely my point. PDM - A Point Well Taken :o) - ettp ~ RHF |
What Does "RG-6" {Coax Cable} Mean ?
RHF wrote:
On Dec 31, 9:17 am, msg wrote: RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF . Belden makes a Direct Burial RG-8X, 7808 I think. Times Microwave also has LMR-240DB. Good luck buying a couple hundred feet. |
What Does "RG-6" {Coax Cable} Mean ?
David wrote: RHF wrote: On Dec 31, 9:17 am, msg wrote: RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF . Belden makes a Direct Burial RG-8X, 7808 I think. Times Microwave also has LMR-240DB. Good luck buying a couple hundred feet. http://www.universal-radio.com/catalog/cable/coax.html See #2247. It's what dxAce uses! |
What Does "RG-6" {Coax Cable} Mean ?
dxAce wrote:
David wrote: RHF wrote: On Dec 31, 9:17 am, msg wrote: RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF . Belden makes a Direct Burial RG-8X, 7808 I think. Times Microwave also has LMR-240DB. Good luck buying a couple hundred feet. http://www.universal-radio.com/catalog/cable/coax.html See #2247. It's what dxAce uses! Check the specs vs Belden 7808 or TM LMR-240 |
What Does "RG-6" {Coax Cable} Mean ?
David wrote: dxAce wrote: David wrote: RHF wrote: On Dec 31, 9:17 am, msg wrote: RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF . Belden makes a Direct Burial RG-8X, 7808 I think. Times Microwave also has LMR-240DB. Good luck buying a couple hundred feet. http://www.universal-radio.com/catalog/cable/coax.html See #2247. It's what dxAce uses! Check the specs vs Belden 7808 or TM LMR-240 But that stuff isn't what dxAce uses! |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 Coax Cable
In article 5f35269e-7050-4123-a599-3fbf071caa92
@s8g2000prg.googlegroups.com, says... On Dec 31, 7:21*am, BDK wrote: In article 43a532e0-63d5-4ae1-b27a-72085c8bbbf8 @t1g2000pra.googlegroups.com, says... On Dec 30, 9:37*pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - *Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - - * *As a complex, however, you're going to have not one mismatch, but - two. One at the output of the Wellbrook loop, and one at the input of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - * *With a reasonably well designed receiver, you'll likely not notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." - - IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) - - Practical Implementation Says : Just Do It ! - Use the RG6 Coax - - Cable -and- enjoy listening to your radios - iane ~ RHF - - *. - Why bother with all that? I've used RG6 coax for decades without - any issues. A 1.5 to 1 SWR is nothing to worry about at all. - - This is just being anal. - - BDK - BDK - That I Am, and . . . Retentive Too ! ~ RHF http://en.wikipedia.org/wiki/Anal_retentive -butt- Then Again I Did Also Write : IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Well, I guess I missed that, I got a phone call when I read it, sorry. BDK |
What Does "RG-6" {Coax Cable} Mean ?
dxAce wrote:
David wrote: RHF wrote: On Dec 31, 9:17 am, msg wrote: RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF . Belden makes a Direct Burial RG-8X, 7808 I think. Times Microwave also has LMR-240DB. Good luck buying a couple hundred feet. http://www.universal-radio.com/catalog/cable/coax.html See #2247. It's what dxAce uses! How long is your run? |
RG-8X {50 Ohm} Coaxial Cable the Better Feed-in-lIne for ShortwaveRadio Listener (SWL) Antennas ?
On Dec 31, 12:03*pm, dxAce wrote:
David wrote: dxAce wrote: David wrote: RHF wrote: On Dec 31, 9:17 am, msg wrote: RHF wrote: snip Extra Protection* for the Buried Coax Cable can be obtained by using Half-Inch (1/2") Black Polyethylene Drip Water Tubing {Hose} as an added Layer of Protection for Buried Coax Cable against damage from Plants, Tree Roots and Animals. I have coax running through 1 1/2" PVC buried at 2 feet but be advised that you must provide a means of draining condensation or include desiccants or provide dry air flow to avoid water in your cables. *In my case, I periodically blow out the pipe with compressed air and also have a 1 inch per foot grade to encourage drainage to one end where the water can then be extracted (blown out). Regards, Michael MSG - Good Advise. ~ RHF *. Belden makes a Direct Burial RG-8X, 7808 I think. *Times Microwave also has LMR-240DB. *Good luck buying a couple hundred feet. - - - http://www.universal-radio.com/catalog/cable/coax.html - - - See #2247. It's what dxAce uses! - - Check the specs vs Belden 7808 or TM LMR-240 - But that stuff isn't what dxAce uses! RG-8X {50 Ohm} Coaxial Cable the Better Feed-in-lIne for Shortwave Radio Listener (SWL) Antennas ? OK - This Is The "Stuff" That 'DX Ace' Uses ! ~ RHF Universal-Radio P/N #2247 = RG-8X {Mini-8} Coaxial Cable http://www.universal-radio.com/catalog/cable/2247.html + Black - Non-Contaminating - Flexible Jacket. + Stranded Copper Center Conductor [16 AWG - 19sx29g] + Foam Dielectric + Braid Bare Copper Outer Conductor 98% Coverage + OD : 0.242" {Mini as in Small OD less than a 1/4"} -$- Price per Foot : 29¢ - That's a Low Price NOTE - Universal-Radio P/N #2247 RG-8X appears to be equivalent to Belden 9258 (RG-8X or Mini-8) Coax Cable. http://www.wehaveparts.com/pages/belden/9258.pdf Universal-Radio States : RG-8X is our most popular Coaxial Cable. It is a favorite for Shortwave Receiving Antennas. READY MADE CABLE ASSEMBLIES : Universal-Radio P/N #0515 - Pre-Assembled RG-8X Coaxial Cable http://www.universal-radio.com/catalog/cable/cable.html 100 Foot Length with PL-259 Plugs on both Ends Price : $29.95* -Note- Considering the 29¢ per Foot Price you get the Two PL-259 Plugs Installed - Sounds like a Deal to me. * This 100 Feet of RG-8X Coax Cable is a competitive Price with 100 Feet of Quad-Shield RG-6 Coax Cable at WalMart http://www.walmart.com/catalog/produ...uct_id=7811235 for $33 which is 33 Cents per Foot. MORE - Universal-Radio Coax Cable Info {Links} : http://www.universal-radio.com/catalog/cable/coax.html http://www.universal-radio.com/catal.../coaxperf.html http://www.universal-radio.com/catal...erf.html#atten INFO - More Info on RG-8X {Mini} Coax Cable http://www.bellscb.com/products/acce...RG-8X_coax.htm 9091 - http://www.therfc.com/coax.htm RG8X - http://www.davisrf.com/ham1/coax.htm 9258 - http://www.wehaveparts.com/pages/belden_cable.htm HOW TO - Fit a PL-259 Plug to RG8X Coaxial Cable. http://tinyurl.com/2w2vj7 eBay - Buying Belden Coax Cable - Beware ! -by- KC9EOA http://tinyurl.com/329nrt co ax ialy yours - iane and a short wave good bye ~ RHF {pomkia} |
RG-6 for HF?
In article ,
David wrote: Telamon wrote: In article , "Brian" wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? I would not buy cable with the wrong impedance especially on the Wellbrook because I don't know how well the amplifier at the head end stands up to reflections. Some amplifiers become less stable into a load other than what it was designed for. Why don't you fire off that question to them. On the wire antennas you will take a hit on performance depending on frequency unless you use transformers on both ends. I'd give it a try. I doubt modern active devices will have any trouble with such a small difference. "I'd give it a try" is meaningless to me in this context because it is going to work. There is no question that it will work. What is in question is how well will it work. Here there would be no harm in "trying" if he already had the coax but he doesn't. He has to buy the coax and he may be able to save a few bucks. Then again he may not save any money. If the transmission line is not properly terminated on both ends then it will have resonances that may interfere with his reception. This is not much different than putting regular in a high compression engine that needs premium gas. The engine will still run OK it's just that you will not get the full performance that the engine can give you. -- Telamon Ventura, California |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 Coax Cable
In article ,
D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. The general rule in a broad band system is to have components matched in order to prevent these complex results of significant reflections. I'll state again that if you already own the coax to try it, especially if you only have interest in certain frequencies or have another radio and antenna to check propagation. If it works where you want to listen then that's just fine but buy the wrong coax? I would not recommend that. -- Telamon Ventura, California |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6Coax Cable
Telamon wrote:
In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. Not every receiver will detect such cancellations at this operating level, and with this magnitude of mismatch. Noise floor, location and ambient noise will render some antenna losses irrelevant in practical listening, and depening on frequency. If you're not working at the limits of performance, small mismatches in a receiving transmission line are trivial. We're not talking about military grade monitoring of picowatt signals, here. The general rule in a broad band system is to have components matched in order to prevent these complex results of significant reflections. I'll state again that if you already own the coax to try it, especially if you only have interest in certain frequencies or have another radio and antenna to check propagation. If it works where you want to listen then that's just fine but buy the wrong coax? I would not recommend that. Sometimes, the economics ARE the issue. |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 CoaxCable
On Jan 3, 9:21*pm, Telamon
wrote: In article , *D Peter Maus wrote: Telamon wrote: In article , *D Peter Maus wrote: Telamon wrote: In article , *D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - *Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF *. * *Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. * *In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. * *Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, *and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. * *And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6Coax Cable
Telamon wrote:
In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. Not every receiver will detect such cancellations at this operating level, and with this magnitude of mismatch. Noise floor, location and ambient noise will render some antenna losses irrelevant in practical listening, and depening on frequency. If you're not working at the limits of performance, small mismatches in a receiving transmission line are trivial. We're not talking about military grade monitoring of picowatt signals, here. This is not about scale. The signal can be very large and go to zero at some frequencies. You are familiar with the Bose noise canceling headphones? Same principle applies here. It IS about scale. And no, it's not the same principle. Noise cancelling headphones seek to remove all the noise. So, the antiwave is of an amplitude approximately equal to the incoming noise. The losses in a receiving antenna transmission line with a small mismatch don't produce anywhere near that level of cancellation. A small mismatch produces a small reflection. A small reflection only produces a partial cancellation. A partial cancellation produces a lower incoming signal at the partial cancellation frequency... the difference being recovered by the sensitivity of the receiver and it's low noise floor. Unless the hobbyist is operating at the limits of performance, that difference will may never be noticed. The general rule in a broad band system is to have components matched in order to prevent these complex results of significant reflections. I'll state again that if you already own the coax to try it, especially if you only have interest in certain frequencies or have another radio and antenna to check propagation. If it works where you want to listen then that's just fine but buy the wrong coax? I would not recommend that. Sometimes, the economics ARE the issue. How much money can he save buying 300 feet of the 75 ohm coax over the 50 ohm? Maybe $30. It IS his budget, after all. And for some, $30 can be a big difference. As I said, that level of investment may not matter to many of the operators in the hobby. You and I wouldn't worry about it. But there are some who have other priorities, and $30 is enough of a deal that it warrants consideration. The bottom line is that he's just getting into the hobby, again. And the way the Wellbrook is designed, his mismatched cable run is on the length between the loop and the preamp. Reflections in that line are going to be small anyway. Cancellations are going to be partial at best, and few in number, pursuant to length vs frequency. His choices will get him up and running. Let him discover for himself how significant the mismatch is. Likely, he'll never detect it as you or I would. |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 Coax Cable
In article
, D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. Not every receiver will detect such cancellations at this operating level, and with this magnitude of mismatch. Noise floor, location and ambient noise will render some antenna losses irrelevant in practical listening, and depening on frequency. If you're not working at the limits of performance, small mismatches in a receiving transmission line are trivial. We're not talking about military grade monitoring of picowatt signals, here. This is not about scale. The signal can be very large and go to zero at some frequencies. You are familiar with the Bose noise canceling headphones? Same principle applies here. It IS about scale. And no, it's not the same principle. Noise cancelling headphones seek to remove all the noise. So, the antiwave is of an amplitude approximately equal to the incoming noise. The losses in a receiving antenna transmission line with a small mismatch don't produce anywhere near that level of cancellation. A small mismatch produces a small reflection. A small reflection only produces a partial cancellation. A partial cancellation produces a lower incoming signal at the partial cancellation frequency... the difference being recovered by the sensitivity of the receiver and it's low noise floor. Unless the hobbyist is operating at the limits of performance, that difference will may never be noticed. Snip Have you calculated this? Have you considered that the coax will not behave as a transmission line but will resonate as part of the antenna system is it is not terminated at its characteristic impedance on both ends? -- Telamon Ventura, California |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6Coax Cable
Telamon wrote:
In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. Not every receiver will detect such cancellations at this operating level, and with this magnitude of mismatch. Noise floor, location and ambient noise will render some antenna losses irrelevant in practical listening, and depening on frequency. If you're not working at the limits of performance, small mismatches in a receiving transmission line are trivial. We're not talking about military grade monitoring of picowatt signals, here. This is not about scale. The signal can be very large and go to zero at some frequencies. You are familiar with the Bose noise canceling headphones? Same principle applies here. It IS about scale. And no, it's not the same principle. Noise cancelling headphones seek to remove all the noise. So, the antiwave is of an amplitude approximately equal to the incoming noise. The losses in a receiving antenna transmission line with a small mismatch don't produce anywhere near that level of cancellation. A small mismatch produces a small reflection. A small reflection only produces a partial cancellation. A partial cancellation produces a lower incoming signal at the partial cancellation frequency... the difference being recovered by the sensitivity of the receiver and it's low noise floor. Unless the hobbyist is operating at the limits of performance, that difference will may never be noticed. Snip Have you calculated this? Have you considered that the coax will not behave as a transmission line but will resonate as part of the antenna system is it is not terminated at its characteristic impedance on both ends? Yes, I have considered that. Again, any resonances based on the small mismatch at the levels involved will be small. |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6 Coax Cable
In article
, D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. Not every receiver will detect such cancellations at this operating level, and with this magnitude of mismatch. Noise floor, location and ambient noise will render some antenna losses irrelevant in practical listening, and depening on frequency. If you're not working at the limits of performance, small mismatches in a receiving transmission line are trivial. We're not talking about military grade monitoring of picowatt signals, here. This is not about scale. The signal can be very large and go to zero at some frequencies. You are familiar with the Bose noise canceling headphones? Same principle applies here. It IS about scale. And no, it's not the same principle. Noise cancelling headphones seek to remove all the noise. So, the antiwave is of an amplitude approximately equal to the incoming noise. The losses in a receiving antenna transmission line with a small mismatch don't produce anywhere near that level of cancellation. A small mismatch produces a small reflection. A small reflection only produces a partial cancellation. A partial cancellation produces a lower incoming signal at the partial cancellation frequency... the difference being recovered by the sensitivity of the receiver and it's low noise floor. Unless the hobbyist is operating at the limits of performance, that difference will may never be noticed. Snip Have you calculated this? Have you considered that the coax will not behave as a transmission line but will resonate as part of the antenna system is it is not terminated at its characteristic impedance on both ends? Yes, I have considered that. Again, any resonances based on the small mismatch at the levels involved will be small. OK, you keep on believing that. Remember you have a mismatch on both ends of the cable. -- Telamon Ventura, California |
Building a 75-to-50 Ohm [1.5:1] Matching Transformer for RG6Coax Cable
Telamon wrote:
In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: Telamon wrote: In article , D Peter Maus wrote: RHF wrote: On Dec 30, 9:37 pm, D Peter Maus wrote: Brian wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - Alone, your receiver won't care. I doubt that the Wellbrook would, - either. - As a complex, however, you're going to have not one mismatch, - but - two. One at the output of the Wellbrook loop, and one at - the input - of - the antenna interface. This may result in standing waves on the - transmission line which, in turn may result in irregularities in - performance. - - With a reasonably well designed receiver, you'll likely not - notice - any losses in practical listening. And unless you are working at the - very limits of performance on signals very far down in the noise and - doing A/B tests of one coax over another, you'll not detect the - performance irregularities. - DPM, Then it becomes a Practical Implementation and CBA type Problem. CBA = Cost Benefit Analysis http://en.wikipedia.org/wiki/Cost-benefit_analysis http://en.wikipedia.org/wiki/Implementation Cost of RG58/RG8 Coax Cable -versus- Cost of RG6 Quad-Shield Coax Cable with a 75-to-50 Ohm Matching Transformer at each end. Starting with the Concept of a 9:1 Matching Transformer for General Broad-Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application with 30 Turns (9-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material : We now need a Matching Transformer to take the Antenna and Radios SO-239 Jack/Plugs {BNC Connector Optional} -to- the 75 Ohm Coax Cable with an F-Connector {BNC Connector Optional} . The 50 Ohm 10 Turns (1-Side) should be understood. Getting to the 75 Ohm (X-Side) should be simple Math : 75 / 50 = 1.5 Square Root of 1.5 = 1.225 Therefore the 75 Ohm (X-Side) would have 12 Turns. A 75 Ohm to 50 Ohm [1.5:1] Matching Transformer would have 12 Turns (1.5-Side) and 10 Turns (1-Side) and the Same Ferrite Core Material -as- 9:1 Matching Transformer for General Broad Band Shortwave Radio (High Frequency 3~30 MHz) Use and Application. Anyone Else Have Any Ideas : On a Building Your Own {DIY} a 75 Ohm to 50 Ohm [1.5:1] Matching Transformer ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - The Next Question Becomes : At What Cost ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers commercial available ? - a Ready Made Item ? Price ? * Are the 75 Ohm to 50 Ohm [1.5:1] Matching Transformers a Low Cost "Built-it-Yourself" Item ? - DIY Price ? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DPM - I go back to your first statement : "Alone, your receiver won't care. I doubt that the Wellbrook would, either." IMHO - For the vast majority of Shortwave Radio Listeners (SWLs) Practical Implementation Says : Just Do It ! - Use the RG6 Coax Cable -and- enjoy listening to your radios - iane ~ RHF . Which was precisely my point. It's dumb to buy cable or anything else that is not matched to the task unless there is some kind of over riding factor such as cost. In your universe, and mine, yeah, you buy the best, brightest, matched, optimized, or NFL approved. Truth is, that in real world operations within the normal parameters hobbyists achieve, there is likely no detectable difference between the 'correct' choice, and the most economical choice for transmission line in this application. And given that the OP was concerned about cost, his choice is a decent one. And unless the OP is intending to operate his system at the limits of performance, any losses incurred will not be relevant to his operation. Would I do it that way? No. Would you do it that way? I'm thinking not. But we're in a different position to make these decisions. And we both have the hardware to not only notice the difference in antenna/transmission line performance, but we operate closer to the limits than the OP. For you and me, the choice of coax may well make a detectable difference. In my case, it would also bother me to install a line that I knew wasn't correct for the application. There are others here with the same attention to detail. And still others who will not hear or detect the differences. You're running RX-340. The minutiae at the antenna can be heard. It's not the case when the best receiver you've ever encountered is Sat-800. Well, yes performance is a critical parameter but I would not frame the discussion around a high performance radio. The radio I own is not the issue as ANY table top radio will be adversely affected in reception performance. The performance issue that will affect ANY radio is due to a recombination of forward and reflected waves that run the gamut of reinforcement to cancelation. Where reinforcement or cancelation of incoming signals will occur will depend on several factors and as a consequence not easy to calculate. You may not ever hear a signal on some frequency because that is where the cancelation occurs. The cancelation has to happen somewhere in the frequency band. If you never listen to that spot or spots then no problem but if it happens where you want listen then tough luck. Not every receiver will detect such cancellations at this operating level, and with this magnitude of mismatch. Noise floor, location and ambient noise will render some antenna losses irrelevant in practical listening, and depening on frequency. If you're not working at the limits of performance, small mismatches in a receiving transmission line are trivial. We're not talking about military grade monitoring of picowatt signals, here. This is not about scale. The signal can be very large and go to zero at some frequencies. You are familiar with the Bose noise canceling headphones? Same principle applies here. It IS about scale. And no, it's not the same principle. Noise cancelling headphones seek to remove all the noise. So, the antiwave is of an amplitude approximately equal to the incoming noise. The losses in a receiving antenna transmission line with a small mismatch don't produce anywhere near that level of cancellation. A small mismatch produces a small reflection. A small reflection only produces a partial cancellation. A partial cancellation produces a lower incoming signal at the partial cancellation frequency... the difference being recovered by the sensitivity of the receiver and it's low noise floor. Unless the hobbyist is operating at the limits of performance, that difference will may never be noticed. Snip Have you calculated this? Have you considered that the coax will not behave as a transmission line but will resonate as part of the antenna system is it is not terminated at its characteristic impedance on both ends? Yes, I have considered that. Again, any resonances based on the small mismatch at the levels involved will be small. OK, you keep on believing that. Remember you have a mismatch on both ends of the cable Yes, that's true. I believe I was the one who first pointed that out to the OP. |
RG-6 for HF?
On Dec 30 2007, 7:45 pm, "Brian" wrote:
I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian While I'm a big fan of Wellbrook gear, I don't like the use of a BNC for anything designed to be used outdoors. Connectors used outdoors should be threaded. I don't recall if the 1530 has any means to weatherproof the BNC. If it doesn't, you might want to think about making one of your own. Since Wellbrook pots their electronics, they may consider than to be enough protection against moisture wicking into the box. Then maybe a bit of sealant around the connector is all you need. |
For Weather-Proofing Your Radio & Antenna Outside Connections - TryCoax-Seal
On Jan 5, 7:42*pm, wrote:
On Dec 30 2007, 7:45 pm, "Brian" wrote: I finally got a house out in the woods on five acres and I'm going to set up a couple of pretty long wires and my Wellbrook ALA-1530. I've pretty much decided on RG-6 for a couple of 150 ft. runs because the stuff's dirt cheap and I can pick it up at the local Home Depot. Is the impedance mismatch here going to be negligible, or should I just bite the bullet and go with RG-8 or a similar 50 ohm coax? -Brian - - While I'm a big fan of Wellbrook gear, I don't like the use - of a BNC for anything designed to be used outdoors. - Connectors used outdoors should be threaded. I don't - recall if the 1530 has any means to weatherproof the BNC. - If it doesn't, you might want to think about making one of - your own. Since Wellbrook pots their electronics, they may - consider than to be enough protection against moisture - wicking into the box. Then maybe a bit of sealant around - the connector is all you need. - M...Sushi, For Weather-Proofing Your Radio & Antenna Outside Connections - Try Coax-Seal Coax-Seal will usually work as a good means of Weather-Proofing most Radio and Antenna Plugs-&-Jacks and other Connections. Coax-Seal works with PL-259 Plugs; SO-239 Jacks; F-Connectors; BNC Connectors; and many many more . . . The "Coax-Seal" WebSite COAX-SEAL - http://www.coaxseal.com/ Manufactured -by- Universal Electronics, Inc. How To Use Coax-Seal http://www.coaxseal.com/How%20to%20Use%20Coax-Seal.htm Where Can I Get Coax-Seal ? http://www.coaxseal.com/Where%20can%...0Coax-Seal.htm http://www.davisrf.com/coaxseal.php http://www.rfparts.com/coax_seal.html http://www.cheapham.com/coax-wire.html http://hamradio.com/cgi-bin/uncgi/ase?MAN=Universal http://www.universal-radio.com/catalog/hamacc/1194.html http://www.mcminone.com/product.asp?...me=MCMProducts sealing the deal against weather with something as simple as . . . 'coax-seal' - iane ~ RHF {pomkia} |
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