Topband: Beverage transformer and testing

[donovanf at starpower.net]

I wind matching transformers for receiving antennas with 30 AWG 
wire wrap wire. A BN73-202 binocular core will accept up to 18 full 
turns (36 passes). The insulation is very tough and it will not short to 
the ferrite core. The insulation is so tough that you'll need a wire 
stripper intended for 30 AWG wire wrap wire. 



https://www.adafruit.com/product/1446 


26 AWG stranded wire from old telephone cables also works very 
well, will not short to the ferrite core and is very easy to strip. 

A BN73-202 binocular core will accept up to 14 turns. 


73 
Frank 
W3LPL 
----- Original Message -----

From: "Mike Waters" <mikewate at gmail.com> 
To: "MR TREVOR DUNNE" <ei2glb at eircom.net> 
Cc: "topband" <topband at contesting.com> 
Sent: Friday, February 2, 2018 6:04:01 PM 
Subject: Re: Topband: Beverage transformer and testing 

The instructions are at 
www.w0btu.com/Beverage_antennas.html 

To test it, put a 450 ohm resistor on the high impedance winding and an 
antenna analyzer on the low-Z. 

And make sure there is infinite resistance between each winding and the 
core, as 73 material is conductive. 

73, Mike 
www.w0btu.com 

On Feb 2, 2018 9:59 AM, "MR TREVOR DUNNE" <ei2glb at eircom.net> wrote: 

Hi I know it's probably been covered here hundreds of times but I'm looking 
to make a matching Transformer for a 550ft beverage to 75 ohm coax, 

I have so bn73-202 cores 

Also how can I test it once it's built 
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