Thanks to Garey and his documentation CD, my birdie problem is resolved! I was able to determine that somewhere in one of my receiver's previous lives a capacitor was added across R83 on the audio board. This provided a feedback loop which caused the audio board to oscillate at approximately 330 KHz. This waveform was clearly visible on the audio output transistor using a scope. It was also backfeeding on the +14 volt buss to the crystal calibrator board which modulated the crystal calibrator output, causing the birdies in the passband of the receiver. Adjusting the volume control changed the frequency of the fundamental oscillation in the audio amp just enough to change the frequencies of the birdies in the passband.
My receiver is now working fine and will be taking its place on my operating table shortly. Without Garey's documentation CD in hand, it would have been a long and tedious search for that capacitor. Thanks again to all! 73 de Bill, K9RZ _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
