Carl Blare

I will post the link to my working version of TalkingPixie2 V1.0 shortwave transmitter which was discussed at great length in a previous thread, during the time I got the audio to modulate.

I will post the link to my working version of TalkingPixie2 V1.0 shortwave transmitter which was discussed at great length in a previous thread, during the time I got the audio to modulate.

http://www.kdxradio.com/pixie2.html

I wish to ask opinions about one very specific portion of this circuit, namely R3 and R5.

In my first working transmitter, Qr (2N222A) was inadvertently damaged, and I replaced it with a part from the junk box, GE-20 (Phillips ECG 123A). This change of transistor caused the modulation to drop to almost nothing, but I found that making R3 = 6.8k and R5 = 10k the full modulation returned.

The question I am asking now, is, what are R3 and R5 doing which so critically matters with regard to the modulation working correctly?

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