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Author Topic: e f johnson coil  (Read 3597 times)
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wd0cfc
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« on: May 01, 2016, 08:07:58 PM »

Can anyone give me specs on this? What it was used in? Picked it up at a hamfest cheap. Want to use it for base loading coil on a ground mounter vertical. Thanks


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w4bfs
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« Reply #1 on: May 01, 2016, 08:52:19 PM »

this was most likely used in a commercial broadcast band transmitter ... should perform well in your base loaded vertical if you keep it dry
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KA2DZT
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« Reply #2 on: May 01, 2016, 08:57:54 PM »

Probably 40-50 uHy.   Someone will know exactly what it is,  probably Dennis W7TFO
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DMOD
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« Reply #3 on: May 01, 2016, 11:16:29 PM »

Can anyone give me specs on this? What it was used in? Picked it up at a hamfest cheap. Want to use it for base loading coil on a ground mounter vertical. Thanks

That what I used in my vertical loading system:

http://amfone.net/Amforum/index.php?topic=36511.0

Phil - AC0OB
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WD8BIL
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« Reply #4 on: May 02, 2016, 10:49:45 AM »

Just guessing at the dimensions I got 46 uh. Here an online calculator you can use. Measure it up and plug in the numbers.

http://www.66pacific.com/calculators/coil_calc.aspx
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John K5PRO
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« Reply #5 on: May 02, 2016, 08:00:49 PM »

It isn't on this list, having four supports instead of three. If you have a bridge, a grid dipper, a AAD LC meter, or anything, you can measure it. (hint: use a known small value capacitor in parallel and measure the resonant freq and calculate L)

* Johnson inductors list.pdf (262.45 KB - downloaded 144 times.)
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n2bc
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« Reply #6 on: May 03, 2016, 10:24:30 PM »

Looks like the one in an RCA BTA-1R1 (L302) - 57uH.   I don't have it any more so cannot check the EFJ number, or measurements, etc.
Bill  N2BC
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