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Some antenna feedline thoughts
This is mainly for newcommers to the SWL hobby
This article formsthe basies of my present SW/HF antenna ground setup. http://members.aol.com/WA1ION/nrants.pdf#search='NRANTS%20pdf This is a simple easy to build 9:1 matching transformer. Please read the rolling your own spliter for soem valid observatios on larger vs small torroids. And John doty's comments on using the feritte "binoculars" from the common TV 300:75 ohm matching tranformer for a really cheap 9:1 makes a lot of sense. http://www.hard-core-dx.com/nordicdx.../9_1balun.html John Doty's ground system. I used this for several years before upgrading to the WA1ION system. A very good system that may not be worth the trouble to improve upon. I had switched to a braid/foil coax and found I still had some birdies from my PC. Isolating the grounds removed the last audible trace of my PC clocks. http://www.anarc.org/naswa/badx/antennas/grounding.html John Doty made some measurements and shows why a 9:1 matching tranformer can help the average antenna receier combo. http://www.anarc.org/naswa/badx/ante..._longwire.html John Doty's low noise antenna design some pratical and workable antenna feedline sugestions. http://www.anarc.org/naswa/badx/ante...e_antenna.html John Doty had a chance to play with a decent radio in a very quite RF location. His comments are interesting and I found them usefull. At the very least it is nice to know that not everyplace is an RF wasteland. http://www.dobe.com/wts/funk/islandexp_JD.html I posted this one before, but even for those who don't wish to use an antenna splitter there is some usefull information. The comments on torroid size and the effects of the measured mismatch to actual receiver performance were especially illustrative. From my own experience in winding 9:1, and other ratio, transformers I found teh smaller feritte cores worked much better. Teh common TV matching binocular is hard to beat in terms of performance and availability. http://www.dxing.info/equipment/roll...own_bryant.pdf There has been and continues to be an ongoing debate over the merits of 50 Ohm coax vs 75 Ohm coax. I have used both and for LF/MW/HF receiving could measure no difference in the RF at the receiver. The Z of the cable had no effect on how well the radios received. This was with a variety of receivers ranging from a R390, R392, R5000, R2000 and a Lowe 150. A complete list would be long and tedious. What I found to be be much more important then the Z of the coax was the amount of shielding. Most braid only coax only has ~95% shielding. I found the 5% leakage allowed noise from my other radio room equipment, PC monitor etc, to enter the coax and added a lot of noise. By going to braid and foil coax I reduced the crud from my PC to negliable, ie below the threashold of reception, levels. I can run audio FFT programs and still find my PC, video board and other clock freqs, but for normal day to day listening they are just gone. John's comments on burrying the coax make sense and I decided to go a little better. I have collected a fair number of feritte RFI control beads over the years. I placed one about every 6~8" for the entire length of the cable. I cann't give any real numbers, but I am certain this helped reduce the common mode leakage on the coax. A similar but easier can be found at: http://www.arising.com.au/people/Hol...ph/CMBalun.htm Almost everyone has a dead AM radio kicking around and this a perfect use for the feritte rod. I have used similar configurations and found them to be nearly as effective as feritte beads or torroids. While this is common sense, it bears repeating:The lower your noise floor, and the lower the man made noise your antenna brings to your receiver the weaker signal you can receive. Since few of us can move to RF quite zones, the only practical action is to improve our antennas and grounds as much as practical. REducing the noise picked up by the antenna and ground can improve a system enough to make you think you just got a new and much better receiver. I am experimenting with the AMRAD LF active antenna and have found that it is very good antenna, and approaches a good long wire most of the time. At LF and VLF it is much quiter then my longwire. I still had to decouple the coax to keep noise from radiating back through the shield and entering the antenna. For the AMRAD a bunch of feritte beads or common mode choke is a must have. Terry |
Terry,
From your past posts I recall you're in Lexington. About 6 or 7 of us central KY DXers get together every so often to DX and shoot the bull. If you'd like to join us or simply say "hi" to some fellow DXers just send an email to jerry at bluegrassdavinci dot.com -- Bluegrass DaVinci Fellowship Central Kentucky Group of Shortwave Enthusiasts http://www.bluegrassdavinci.com/ |
JerryJ wrote:
Terry, From your past posts I recall you're in Lexington. About 6 or 7 of us central KY DXers get together every so often to DX and shoot the bull. If you'd like to join us or simply say "hi" to some fellow DXers just send an email to jerry at bluegrassdavinci dot.com -- Bluegrass DaVinci Fellowship Central Kentucky Group of Shortwave Enthusiasts http://www.bluegrassdavinci.com/ Do you know where Frenchburg is? ;-) -- Former professional electron wrangler. Michael A. Terrell Central Florida |
A lot of good info. Thank you.
Al KA5JGV wrote in message oups.com... This is mainly for newcommers to the SWL hobby http://members.aol.com/WA1ION/nrants.pdf#search='NRANTS%20pdf http://www.hard-core-dx.com/nordicdx.../9_1balun.html http://www.anarc.org/naswa/badx/antennas/grounding.html http://www.anarc.org/naswa/badx/ante..._longwire.html http://www.anarc.org/naswa/badx/ante...e_antenna.html http://www.dobe.com/wts/funk/islandexp_JD.html http://www.arising.com.au/people/Hol...ph/CMBalun.htm Terry |
Michael A. Terrell wrote:
Do you know where Frenchburg is? ;-) ---------------------------- Yes it is about an hour or so south east of Lexington. My wife and I often go to the RRG area for hiking, picnics and mini DX-epiditions. Terry |
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"Michael A. Terrell" wrote in message ... wrote: Michael A. Terrell wrote: Do you know where Frenchburg is? ;-) ---------------------------- Yes it is about an hour or so south east of Lexington. My wife and I often go to the RRG area for hiking, picnics and mini DX-epiditions. Terry My family left the area in the early '50s and the last time I was back there was 1966 for a funeral. Its a beautiful area. -- Former professional electron wrangler. Michael A. Terrell Central Florida Funny - I worked for a radio station in Topeka, back in 1992. I've enjoyed a friendship with the station's chief engineer since then. We drove down to Prestonsburg to pick up a 50kW FM transmitter and its plate transformer, and stayed for the weekend in Salt Lick, KY, just a stone's throw from Frenchburg. We managed to have lunch in Frenchburg. That really is "God's Country," and I've thought ever since that it might be a nice place to retire. That transmitter was quite an adventure - the tower site was perched on top of a mountain overlooking Prestonsburg. We were driving a 20-ish-foot Ryder truck, and the road up the mountainside was impassable, mud, probably a foot deep. The road was *very* narrow, and the drop was (I kid you not) well over a thousand feet. A local contractor pulled us up the mountainside with an ancient Cat, and the swaying of the truck as we crawled up....Phew. I imagine the dashboard of that truck still has holes in it. I was lucky to have a "mountain side" seat on the way up. If I'd opened up the door, I'd have probably fallen at least 50 feet before the first bounce. Nice folks, though. I don't think I've ever felt so at home. I remember the traffic jams, too...just coal trucks. 73, Steve Lawrence Burnsville, Minnesota Every moment of a human life is an act of worship. Coincidence is God's way of being anonymous. |
Beautiful but impoverished.
I was born in eastern KY in teh early 50's and my parents moved to Lexington whne I was 3 months old. We own the old family "homestead", but it would be hard to scratch out a living there. I do like eastern KY for the scenery and the DXing locations. Crystal meth and oxycodone have hit the mountain folk hard. At times it feels like everyone left is either a speed freak or oxy adict. Terry |
wrote:
Beautiful but impoverished. I was born in eastern KY in teh early 50's and my parents moved to Lexington whne I was 3 months old. We own the old family "homestead", but it would be hard to scratch out a living there. I do like eastern KY for the scenery and the DXing locations. Crystal meth and oxycodone have hit the mountain folk hard. At times it feels like everyone left is either a speed freak or oxy adict. Terry How awful. Well, I was there over a decade ago, and I saw the same thing happening in Topeka at that time. That's some pretty insidious garbage, and I count my blessings that I'm not predisposed to anything more addictive than coffee and cigars. I do remember looking at a number of "pastures" and wondering how they could scratch out anything but goats or sheep with a soil depth of 3 inches, and fields *full* of rocks, though. I've got a friend in Bean Station, TN with the same kind of soils, but the guy's a genius, and has managed to raise hogs and chickens on his 40 acres. You're absolutely correct about the DX potential of that locale. I spent a week with my friend in Bean Station, and at the time, he was building his home (I did his wiring), and was surprised at the lack of electrical noise. The old FRG-7 "heard" some stuff that is usually "unhearable" here in the Twin Cities. I also had an AEA DX Handie and ten meters was open. What fun! 73, Steve Steve Lawrence Burnsville, Minnesota Every moment of a human life is an act of worship. Coincidence is God's way of being anonymous. |
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anhydrous amonia
The meth cookers steal it from farm supply depots. They often sotre/transport it in 25lb propane tanks. A friend found a "brand new" 25lb tank on the side of a busy highway. Took it home, hooked it up to his barbecue and damn near killed himslef and his family when the amonia came out. The fire department and police told him he was very lucky becasue anhydrous amonia is one nasty chemical. Every few weeks the police catch a mobile meth lab and they have to evacuate the area. They shut down I75 about a year ago when a mobile meth lab sprang a leak. The amonia burned the cookers pretty bad, and I75 was closed for about 12 hours. A cop told me that they are waiting for some meth lab to kill a neighborhood. Just what the world needs, some doped out moron using anhydrous amonia. I am amazed that there aren't more events. Terry Terry |
For info check out the MSDS for anhydrous ammonia.
http://www.wdserviceco.com/MSDSANHY.html This crap is something I want to avoid. Terry |
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I've never been to Frenchburg, though I've been to Natural Bridge a
couple of times. Very scenic out that way. |
The Red River Gorge wilderness area is very close to Natural Bridge.
If you are willing to hike a few miles you can get awy from power lines, people and their noisy cars. With a DX398, or 2, and 2 roughly equal length pices of 50 to 100 feet of wire, and some nylon monofilimanet you can have a wonderfull easy mini DX party. While the ridges are best, even the valleys are very good. By using two roughly equal wire onteh DX398 we have found the addional wire makes singals several "S" units stronger. Not a dipole, but more as a counter-poise. Late fall and early spring are our favorite times. Fewer ticks and no crowds Even Natural Bridge is great in the off season. Just don't string an antenna on the brdige. :) Terry |
"Stephen M.H. Lawrence" wrote:
Funny - I worked for a radio station in Topeka, back in 1992. I've enjoyed a friendship with the station's chief engineer since then. We drove down to Prestonsburg to pick up a 50kW FM transmitter and its plate transformer, and stayed for the weekend in Salt Lick, KY, just a stone's throw from Frenchburg. We managed to have lunch in Frenchburg. That really is "God's Country," and I've thought ever since that it might be a nice place to retire. I was a teenager the last time I was there but I still remember the clean air, the rolling hills and all that Kentucky Bluegrass where it had spread all over the hills and mountainsides. The other thing i remember was how quiet the radio and TV bands were. There was no manmade noise on most bands so all you heard was a few radio stations or bursts of static when a storm was pounding away at a mountain top. Did you see "Broke leg Falls"? Its about ten miles from Frenchburg and a popular tourist stop. I moved a 25 KW UHF TV transmitter from Leesburg, Fl. to Destin Fl around that time. It took four 28 foot Ryder trucks to haul all the parts and the water chillier for the final tubes. The transmitter was built in '52 in nine, three foot square aluminum cabinets. It was a RCA TTU-25B which was one of the first "high lower" UHF transmitters. That transmitter was quite an adventure - the tower site was perched on top of a mountain overlooking Prestonsburg. We were driving a 20-ish-foot Ryder truck, and the road up the mountainside was impassable, mud, probably a foot deep. The road was *very* narrow, and the drop was (I kid you not) well over a thousand feet. A local contractor pulled us up the mountainside with an ancient Cat, and the swaying of the truck as we crawled up....Phew. I imagine the dashboard of that truck still has holes in it. I was lucky to have a "mountain side" seat on the way up. If I'd opened up the door, I'd have probably fallen at least 50 feet before the first bounce. Nice folks, though. I don't think I've ever felt so at home. I remember the traffic jams, too...just coal trucks. 73, Steve Lawrence I still have a few relatives up there. One of them had a big rock quarry called "Acme". Others farmed, made Sorghum and raised thousands of chickens. -- Former professional electron wrangler. Michael A. Terrell Central Florida |
wrote:
A cop told me that they are waiting for some meth lab to kill a neighborhood. Just what the world needs, some doped out moron using anhydrous amonia. I am amazed that there aren't more events. Terry That anyhdrous is nasty stuff. When it re-wets, it reacts violently with water, and destroys an amazing amount of lung tissue in a very short time. I am surprised that the gummint pays so much attention to pot, but leaves meth enforcement to the local sheriffs. 73, Steve -- Steve Lawrence Burnsville, Minnesota Every moment of a human life is an act of worship. Coincidence is God's way of being anonymous. |
"Michael A. Terrell" wrote: I was a teenager the last time I was there but I still remember the clean air, the rolling hills and all that Kentucky Bluegrass where it had spread all over the hills and mountainsides. The other thing i remember was how quiet the radio and TV bands were. There was no manmade noise on most bands so all you heard was a few radio stations or bursts of static when a storm was pounding away at a mountain top. Did you see "Broke leg Falls"? Its about ten miles from Frenchburg and a popular tourist stop. I don't remember being there, so I'll bet that, if we went through, I was probably catching up on sleep. I moved a 25 KW UHF TV transmitter from Leesburg, Fl. to Destin Fl around that time. It took four 28 foot Ryder trucks to haul all the parts and the water chillier for the final tubes. The transmitter was built in '52 in nine, three foot square aluminum cabinets. It was a RCA TTU-25B which was one of the first "high lower" UHF transmitters. If I recall correctly, this was an RCA BTH 40, an "E" model, but it's been some time. We had an easier time than you, but it did take 6 men to lift and move that darned plate transformer. I enjoyed the "ride" back down, because I wasn't looking straight down. I'm surprised folks can raise sorghum there, but I don't know much about the soil conditions. Chickens, on the other hand, are a "snap." ;P 73, Steve Steve Lawrence Burnsville, Minnesota Every moment of a human life is an act of worship. Coincidence is God's way of being anonymous. |
Stephen M.H. Lawrence wrote:
That anyhdrous is nasty stuff. When it re-wets, it reacts violently with water, and destroys an amazing amount of lung tissue in a very short time. I am surprised that the gummint pays so much attention to pot, but leaves meth enforcement to the local sheriffs. ---------------------------------------- I am waiting for a cooker to blow a "make" and have a major leak that wipes out a few dozen to hundred. And HS is worried about al-Qaida. We have thosands of nut jobs brewing meth all over the country. In a desperate attempt to bring it under "control", the KY legislature has made it illegal for anyone to have more then about 26 allergy pills in their home. Yea that is going to really slow down people who will mess with something that will kill you. It is difficult to buy primary Lithium cells around here. Stores can't keep them on the shelf because the dopeheads steal them so fast. Ether starting fluid is also getting hard to get. Terry |
wrote in message
ups.com... Stephen M.H. Lawrence wrote: That anyhdrous is nasty stuff. When it re-wets, it reacts violently with water, and destroys an amazing amount of lung tissue in a very short time. I am surprised that the gummint pays so much attention to pot, but leaves meth enforcement to the local sheriffs. ---------------------------------------- I am waiting for a cooker to blow a "make" and have a major leak that wipes out a few dozen to hundred. And HS is worried about al-Qaida. We have thosands of nut jobs brewing meth all over the country. In a desperate attempt to bring it under "control", the KY legislature has made it illegal for anyone to have more then about 26 allergy pills in their home. Yea that is going to really slow down people who will mess with something that will kill you. It is difficult to buy primary Lithium cells around here. Stores can't keep them on the shelf because the dopeheads steal them so fast. Ether starting fluid is also getting hard to get. Terry It occurs to me that some folks add a couple of ounces of acetone to their fuel tank to improve gas mileage and clean their coked pistons and cylinders. I wonder if they're getting harangued for doing so? The same ban is in effect here in Uber-Liberal land; I can only buy 2 boxes of Sudafed (the only thing that kills those nasty sinus headaches I get 12-20 times a year) at a time. Like you, I highly doubt that any such effort will put an end to meth production. FWIW, meth has wiped out some communities in Iowa. It's truly evil. 73, Steve Lawrence Burnsville, Minnesota Every moment of a human life is an act of worship. Coincidence is God's way of being anonymous. |
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