TheRadioBoard

In another thread, AB8IF and I were discussing full-break-in transmit-receive switches using vacuum tubes. AB8IF mentioned seeing one in "Understanding Amateur Radio," and the source article may have been in QST for January 1961, by Lew McCoy. Here's the schematic, which should tell you all you need to know. I'd use a 400-PIV 1-amp silicon diode (1N4007) instead of the selenium rectifier specified.



73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

I used a Johnson T/R switch for many years; ;just sold it recently. Don't remember which tube it used, but was probably similar. Seems like SSB transceivers killed the interest/need for electronic T/R.

Rich

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Homebrew Radio ex-Silicon Valley

Yes, when you didn't have to turn on/off a big carrier, VOX (voice-operated transmit) was feasible. Most transmitters and transceivers adapted VOX for CW, giving "semi-break-in." And thus began the ruination of CW as we once knew it.

73,

_________________

http://kr1s.kearman.com/
http://qrp.kearman.com/

Here"s Johnsons version. A little more indepth, but I prefer the 6AH6 version.



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