Thanks to all who responded. This morning I got a significant clue: Following up on Tony Fishpool's suggestion, I separated the power supplies: I ran the RF amp, oscillator and mixer base bias off a small 12 V battery, with the mixer collector circuit and the AF amps running of the bench 12V supply. The AF oscillations completely stop under these conditions. So the feedback is probably taking place via the 12 V supply lines. 73
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The Radio Shack • Ingenuity - simple electro-magnetic toy - Peoples ingenuity never fails to amaze me. https://www.youtube.com/watch?v=J9b0J29OzAU ............. Statistics: Posted by golfguru — Wed Apr 26, 2017 10:2...
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