[AMRadio] Another 813 TX question


CL in NC via AMRadio amradio at mailman.qth.net
Fri Mar 27 02:04:19 EDT 2015


A while back, a friend gave me a homebrew transmitter with and 813 final to check out.  It had a bad plate xfmr, gave it back to him to let him see if he could find a replacement for it.  It was intended for CW only for 80-20, but had a novel AM section added at a later date apparently.  The 'modulator' was nothing more than a transformer put in series with the 813 grid bias, and the primary was fed with a carbon mic, with low voltage fed through it, the primary and ground.  I never did get the TX back, but I did plug a carbon mic in and looked at the grid with a scope and there was quit a bit of audio there. There was no gain control other than talking loud or louder I guess.  Anybody ever run across this circuit or used it and how did it sound and what kind of percent mod did it give?

Charlie, W4MEC in NC


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