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for those that don't want to try and build one, the seller rfjunkie on
ebay sells well built ones really cheap (RHF) wrote in message . com... Building a Matching Transformer for Shortwave Listener's Antenna using a Binocular Ferrite Core from a TV type Matching Transformer. - - - - - - - R E F E R E N C E - S O U R C E - - - - - - - From: (John Doty) Newsgroups: rec.radio.shortwave Subject: Low Noise Antenna Connection Date: 26 Nov 1993 16:55:24 GMT "The transformer is built around a toroid extracted from a TV "matching transformer". If you're a pack rat like me, you have a few in your basement: you typically get one with every TV or VCR (or you can buy one). Pop the plastic case off and snip the wires from the toroid (it looks either like a tiny donut, or a pair of tiny donuts stuck together). The transformer windings should be made with thin wi I use #32 magnet wire. * The primary is 30 turns while * The secondary is 10 turns. For a one-hole toroid, count each passage of the wire down through the hole as one turn. For a two-holer, each turn is a passage of the wire down through the right hole and up through the left.? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - MY BINOCULAR FERRITE CORE MATCHING TRANSFORMER PROJECT: Well I tried two different "Binocular" Ferrite Core to 'build' a Shortwave Listeners Matching Transformer for a Low Noise Antenna. I was using #30 Magnet Wire and these Ferrite Cores are very small 'tiny': 5.0mm H x 6.6mm W x 3.6mm OD x 1.8mm ID But the maximum number of turns that I could get "In" and "Out" of the two small holes was 14 Turns. So I had to settle for a Primary of 9 Turns with a Secondary of 3 Turns. This would be equal to Primary of 18 Turns and a Secondary of 9 Turns using a standard One-Hole {Donut} Toroid Ferrite Core. Has anyone built one of these with this few number of turns and: If So ? How Does It Work ? * * * * * Binocular Ferrite Core TIPS * * * * Here are some things to be Mindful of and Consider during the Matching Transformer Winding Process: * For these 'tiny' Binocular Ferrite Cores; you will be using the same small size AWG #30 Wire for both Windings. So in your Stationary-End of the Primary Winding "Tie" an Overhand Knot to Identify 'it' after you have completed all your Windings. * After your first One and a Half Turns (1 1/2T) with the Wire Ends coming out of the Core from Opposite Sides PULL on both Wire Ends to Tighten the Wire Wraps (Loops) * Each Full Turn after the first 1 ½ Turns: 2 1/2T, 3 1/2T, 4 1/2T, 5 1/2T, 6 1/2T, 7 1/2T, 8 1/2T, 9 1/2T, ETC; with the Wire Ends coming out of the Core from Opposite Sides PULL on both Wire Ends to Tighten the Wire Wraps (Loops) * Wrap the Primary {Antenna}Turns First and Get-Them-Tight. * Place a Pencil and paper next to where your are wrapping the Wire through the Binocular Ferrite Core; and Mark Down Each Turn as you wind it. I Prefer to start my 'count' When I start the Return-Pass-Through of the Wire. [Starting from the Bottom the Wire goes Up (Out) through One Hole and then the Wire goes Down (Returns) through The Second Hole.] * Start the Secondary Turns from the Opposite-End from the Primary Turns. Wrap the Secondary {Coax Cable} Turns and Get-Them-Tight. * If the Primary and Secondary are going to share a Common Ground then take one Primary Wire End and one Secondary Wire End and Twist them together. [ Do Not Use the Primary Wire with the Knot at it's End for one of the Ground Wires.] You will now have a "T" Shape Matching Transformer Assembly. At the 'center' of the "T" will be the Binocular Ferrite Core. The Vertical Leg of the "T' will be the Two Twisted Ground Wires. The Left-Arm of the "T" will be the Primary {Antenna} Wire with the Knot at the End. The Right-Arm of the "T" will be the Secondary {Coax Cable} Wire. If you are making several of these TV Binocular Ferrite Core Matching Transformers. Them you may wish to use some Model Paint of Nail Polish to Mark the Leads for easy visual identification of the Leads as you are working with them. Red - Primary {Antenna} Wire. Green - Secondary {Coax Cable} Wire Black - Two Twisted {Ground} Wires . . Some Say: On A Clear Day You Can See Forever. I BELIEVE: On A Clear Night . . . You Can Hear Forever and Beyond - The Beyond ! . . iane ~ RHF . Check-Out the Shortwave Listeners (SWLs) Antenna eGroup on YAHOO ! http://groups.yahoo.com/group/Shortw...na/message/502 . . |
#3
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TC,
I would agree that RF Junkie's SWL 'baluns' are good performers at a low cost. That is the 'standard' that I am trying to match. Read: Two Shortwave Listener (SWL) 10:1 Baluns for Random Wire Antennas http://groups.yahoo.com/group/Shortw...a/message/1523 http://groups.yahoo.com/group/Shortw...a/message/1528 Good News: Just got a package Binocular Ferrite Cores from UniversalRadio.Com. These are a Lot Bigger and should make the 15 Turns and 5 Turns on the Core a lot easier. Amidon # BN-43-202 Size: 0.525" OD x 0.150" ID x 0.550" Hgt x 0.295" Thk [ 15T x 2H = 30 Turns and 5T x 2H = 10 Turns for a 9:1 Ratio ] Plan on using a 100 Strand #44 AWG Litz Wire for the Secondary with a #26 AWG Magnet Wire for the Primary. Wind the Secondary first on the Core and then cover with the Primary. Any one use Litz Wire for their SWL Matching Transformers ? NOTE: It is my 'hope' that the Litz Wire Secondary will improve the AM/MW Broadcast Band Frequency characteristics of this Matching Transformer. If not, then I will try building one with both Sets of Windings made of Litz Wire. iane ~ RHF .. .. = = = (the captain) wrote in message = = = . com... for those that don't want to try and build one, the seller rfjunkie on ebay sells well built ones really cheap (RHF) wrote in message . com... Building a Matching Transformer for Shortwave Listener's Antenna using a Binocular Ferrite Core from a TV type Matching Transformer. - - - - - - - R E F E R E N C E - S O U R C E - - - - - - - From: (John Doty) Newsgroups: rec.radio.shortwave Subject: Low Noise Antenna Connection Date: 26 Nov 1993 16:55:24 GMT "The transformer is built around a toroid extracted from a TV "matching transformer". If you're a pack rat like me, you have a few in your basement: you typically get one with every TV or VCR (or you can buy one). Pop the plastic case off and snip the wires from the toroid (it looks either like a tiny donut, or a pair of tiny donuts stuck together). The transformer windings should be made with thin wi I use #32 magnet wire. * The primary is 30 turns while * The secondary is 10 turns. For a one-hole toroid, count each passage of the wire down through the hole as one turn. For a two-holer, each turn is a passage of the wire down through the right hole and up through the left.? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - MY BINOCULAR FERRITE CORE MATCHING TRANSFORMER PROJECT: Well I tried two different "Binocular" Ferrite Core to 'build' a Shortwave Listeners Matching Transformer for a Low Noise Antenna. I was using #30 Magnet Wire and these Ferrite Cores are very small 'tiny': 5.0mm H x 6.6mm W x 3.6mm OD x 1.8mm ID But the maximum number of turns that I could get "In" and "Out" of the two small holes was 14 Turns. So I had to settle for a Primary of 9 Turns with a Secondary of 3 Turns. This would be equal to Primary of 18 Turns and a Secondary of 9 Turns using a standard One-Hole {Donut} Toroid Ferrite Core. Has anyone built one of these with this few number of turns and: If So ? How Does It Work ? * * * * * Binocular Ferrite Core TIPS * * * * Here are some things to be Mindful of and Consider during the Matching Transformer Winding Process: * For these 'tiny' Binocular Ferrite Cores; you will be using the same small size AWG #30 Wire for both Windings. So in your Stationary-End of the Primary Winding "Tie" an Overhand Knot to Identify 'it' after you have completed all your Windings. * After your first One and a Half Turns (1 1/2T) with the Wire Ends coming out of the Core from Opposite Sides PULL on both Wire Ends to Tighten the Wire Wraps (Loops) * Each Full Turn after the first 1 ½ Turns: 2 1/2T, 3 1/2T, 4 1/2T, 5 1/2T, 6 1/2T, 7 1/2T, 8 1/2T, 9 1/2T, ETC; with the Wire Ends coming out of the Core from Opposite Sides PULL on both Wire Ends to Tighten the Wire Wraps (Loops) * Wrap the Primary {Antenna}Turns First and Get-Them-Tight. * Place a Pencil and paper next to where your are wrapping the Wire through the Binocular Ferrite Core; and Mark Down Each Turn as you wind it. I Prefer to start my 'count' When I start the Return-Pass-Through of the Wire. [Starting from the Bottom the Wire goes Up (Out) through One Hole and then the Wire goes Down (Returns) through The Second Hole.] * Start the Secondary Turns from the Opposite-End from the Primary Turns. Wrap the Secondary {Coax Cable} Turns and Get-Them-Tight. * If the Primary and Secondary are going to share a Common Ground then take one Primary Wire End and one Secondary Wire End and Twist them together. [ Do Not Use the Primary Wire with the Knot at it's End for one of the Ground Wires.] You will now have a "T" Shape Matching Transformer Assembly. At the 'center' of the "T" will be the Binocular Ferrite Core. The Vertical Leg of the "T' will be the Two Twisted Ground Wires. The Left-Arm of the "T" will be the Primary {Antenna} Wire with the Knot at the End. The Right-Arm of the "T" will be the Secondary {Coax Cable} Wire. If you are making several of these TV Binocular Ferrite Core Matching Transformers. Them you may wish to use some Model Paint of Nail Polish to Mark the Leads for easy visual identification of the Leads as you are working with them. Red - Primary {Antenna} Wire. Green - Secondary {Coax Cable} Wire Black - Two Twisted {Ground} Wires . . Some Say: On A Clear Day You Can See Forever. I BELIEVE: On A Clear Night . . . You Can Hear Forever and Beyond - The Beyond ! . . iane ~ RHF . Check-Out the Shortwave Listeners (SWLs) Antenna eGroup on YAHOO ! http://groups.yahoo.com/group/Shortw...na/message/502 . . |
#4
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This pdf is quite useful:
http://members.aol.com/DXerCapeCod/z_transformers.pdf It takes you through how to do the calculations for any torroid that you purchase. Large torroids and Wire Wrap wire (solid core) are quite effective and easy to handle. I found that Type 43 material with even with windings for 2 mhz and above is still quite effective for MW. Effective enough that I get images on my Tecsun PL-550 between 2 mhz and 3 mhz of distant MW broadcast stations that disappear when I unplug the antenna. |
#5
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CF,
Thank You - For the Link to "Fabricating Impedance {Matching} Transformers for Receiving Antennas" - by John Bryant - May 2001 http://members.aol.com/DXerCapeCod/z_transformers.pdf Good Reading and Worth Printing Out for Future Reference. Now it looks like it is back to the Drawing Boards. Guess I will make out a Spread Sheet for a couple of different Ferrite Cores and start winding. iane ~ RHF .. .. = = = Conan Ford wrote in message = = = 3.159... This pdf is quite useful: http://members.aol.com/DXerCapeCod/z_transformers.pdf It takes you through how to do the calculations for any torroid that you purchase. Large torroids and Wire Wrap wire (solid core) are quite effective and easy to handle. I found that Type 43 material with even with windings for 2 mhz and above is still quite effective for MW. Effective enough that I get images on my Tecsun PL-550 between 2 mhz and 3 mhz of distant MW broadcast stations that disappear when I unplug the antenna. .. |
#6
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RHF wrote: CF, Thank You - For the Link to "Fabricating Impedance {Matching} Transformers for Receiving Antennas" - by John Bryant - May 2001 http://members.aol.com/DXerCapeCod/z_transformers.pdf Here's another: http://www.dxing.info/equipment/impe...ing_bryant.pdf Both posted here, many, many times. dxAce Michigan USA |
#7
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= = = dxAce wrote in message
= = = ... RHF wrote: CF, Thank You - For the Link to "Fabricating Impedance {Matching} Transformers for Receiving Antennas" - by John Bryant - May 2001 http://members.aol.com/DXerCapeCod/z_transformers.pdf Here's another: http://www.dxing.info/equipment/impe...ing_bryant.pdf Both posted here, many, many times. dxAce Michigan USA .. DX ACE, Thank You Too - For the Link to "Impedance Matching Transformers for Receiving Antennas at Medium and Lower Shortwave Bands" - by Bill Bowers & John Bryant & Nick Hall-Patch - July 2003 http://www.dxing.info/equipment/impe...ing_bryant.pdf More Good Reading all 26 Pages of it. Again this was something Worth Printing Out for Future Reference. Got the Spread Sheets done for these Ferrite Cores: Amidon Binocular Ferrite Core # BN-43-202 - Lowest Frequency 500 kHz - Primary 15 Turns x Two Holes = 30T - Secondary 5 Turns x Two Holes = 10T - Matching Transformer Ratio 9:1 Amidon Toroid "Donut" Ferrite Core # BN-82-43 - Lowest Frequency 500 kHz - Primary 32 Turns - Secondary 11 Turns - Matching Transformer Ratio 9:1 Amidon Toroid "Donut" Ferrite Core # BN-50-43 - Lowest Frequency 500 kHz - Primary 33 Turns - Secondary 11 Turns - Matching Transformer Ratio 9:1 Amidon Toroid "Donut" Ferrite Core # BN-114-43 - Lowest Frequency 500 kHz - Primary 31 Turns - Secondary 11 Turns - Matching Transformer Ratio 9:1 I AM GETTING AN "IDEA" ) Run a 75 Foot Inverted "L" Antenna using Landscaping Lighting Cable (Heavy Duty Zip Cord). Making the two 'separate' Antenna Elements two "Parallel" Multi-Stranded Insulated Wires: For the Shortwave Bands - Hook-Up the 1ST Wire to a Matching Transformer made with a Amidon Toroid "Donut" Ferrite Core BN-114-43 using #20 AWG Magnet Wi - Lowest Frequency 1800 kHz - Primary 17 Turns - Secondary 6 Turns - Matching Transformer Ratio 9:1 Separate Coax Cable Feed-in-Line For the Long Wave and AM/MW Bands - Hook-Up the 2ND Wire to a Matching Transformer made with a Amidon Toroid "Donut" Ferrite Core BN-114-75 using 100 Strand #44 AWG 'Litz' Wi - Lowest Frequency 150 kHz - Primary 25 Turns - Secondary 8 Turns - Matching Transformer Ratio 9:1 Separate Coax Cable Feed-in-Line Test them Side-by-Side for both Shortwave and LW/AM/MW performance. iane ~ RHF .. .. |
#8
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In article ,
(RHF) wrote: CF, Thank You - For the Link to "Fabricating Impedance {Matching} Transformers for Receiving Antennas" - by John Bryant - May 2001 http://members.aol.com/DXerCapeCod/z_transformers.pdf Good Reading and Worth Printing Out for Future Reference. Now it looks like it is back to the Drawing Boards. Guess I will make out a Spread Sheet for a couple of different Ferrite Cores and start winding. iane ~ RHF . . = = = Conan Ford wrote in message = = = 3.159... This pdf is quite useful: http://members.aol.com/DXerCapeCod/z_transformers.pdf It takes you through how to do the calculations for any torroid that you purchase. Large torroids and Wire Wrap wire (solid core) are quite effective and easy to handle. I found that Type 43 material with even with windings for 2 mhz and above is still quite effective for MW. Effective enough that I get images on my Tecsun PL-550 between 2 mhz and 3 mhz of distant MW broadcast stations that disappear when I unplug the antenna. . I vote for MATERIAL K. http://www.bytemark.com/products/ferrmat.htm -- Telamon Ventura, California |
#9
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dxAce wrote in :
RHF wrote: CF, Thank You - For the Link to "Fabricating Impedance {Matching} Transformers for Receiving Antennas" - by John Bryant - May 2001 http://members.aol.com/DXerCapeCod/z_transformers.pdf Here's another: http://www.dxing.info/equipment/impe...ing_bryant.pdf Thank you for the link. I've been using the side-by-side winding method on a FT114-43 core, and thanks to that article I will give the Overlapped Winding a try. |
#10
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= = = Conan Ford wrote in message
= = = 23.159... dxAce wrote in : RHF wrote: CF, Thank You - For the Link to "Fabricating Impedance {Matching} Transformers for Receiving Antennas" - by John Bryant - May 2001 http://members.aol.com/DXerCapeCod/z_transformers.pdf Here's another: http://www.dxing.info/equipment/impe...ing_bryant.pdf Thank you for the link. I've been using the side-by-side winding method on a FT114-43 core, and thanks to that article I will give the Overlapped Winding a try. CF, TIP: For a 9:1 Matching Transformer on a Toroidal (Donut) Ferrte Co Use the right size Magnet Wire so that you have 83%/300* to 91%/330* Coverage of the Surface of the Ferrite's ID by the Primary Winding of 30-33 Turns. Then on the Ferrite's OD Surface take a Tooth Pick and use it to create a "Space" {Gap} 'between' every Third Turn of the Primary Windings. [Three Turns + Space + Three Turns + Space + ETC] The simply Overlay the Secondary Windings of 10-11 Truns; using the "Space" {Gap} in Ferrite's OD Primary Windings as your WRAP-GAGE. iane ~ RHF .. .. |
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