[Guest]

Regarding the audio feedback; be sure the tubes shields are making good ground contact with the tube socket shield bases. Shields are on the 75, both 78s, 6A7, for a total of four in this model. Also be sure the grid cap lead of the 75 runs inside the shield.

All the cans were on and the grid cap lead for the 75 was INSIDE. I stared at it for a while, looked at the schematic to see if I missed something. Then I took my ohmmeter and checked the can to the chassis, guess what, very high resistance. I took off the can and looked inside the bottom and it was corroded a bit so I took some emery cloth and cleaned it up. Then looking at the tube socket connection with the can, it too was corroded. I cleaned that and did the same on all the cans and sockets. NO MORE Squeal. I guess I did overlook something, RUST! This chassis has been in use pretty much daily at least since 1975. Electrically it was upgraded but not the chassis. Over the years I guess corrosion built up where the two dissimilar metals contacted.
Thanks for the help in getting me in the correct order.

I did an alignment and the top two bands came in beautifully. 10 and 2.5 and 5.0 for WWV were dead on. But on the Am band while its right on the money, the oscillator still dumps out at about 640Khz. I replaced the three micas in the circuit but it still stops. I have 3 6A7's they all test good but they all work the same so I assume its something in the circuit. Any other Ideas on that?

Again thanks a lot.
David