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Title: e f johnson coil Post by: wd0cfc 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
Title: Re: e f johnson coil Post by: w4bfs 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
Title: Re: e f johnson coil Post by: KA2DZT on May 01, 2016, 08:57:54 PM Probably 40-50 uHy. Someone will know exactly what it is, probably Dennis W7TFO
Title: Re: e f johnson coil Post by: DMOD 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 Title: Re: e f johnson coil Post by: WD8BIL 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 (http://www.66pacific.com/calculators/coil_calc.aspx) Title: Re: e f johnson coil Post by: John K5PRO 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)
Title: Re: e f johnson coil Post by: n2bc 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. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Bill N2BC |