HW-101 Saga

[K7SZ]

Gang:

I have been going crazy with this receiver. Got the HFO and VFO aligned properly. NOW, the problem is an audio howl. 

When you advance the RF gain from full CCW to CW, about 3/4 of the way around the control, the receiver starts to howl...a very annoying audio screech that I haven't been able to track down.

It seems to be in the area of V13, and the product detector. 

I have resoldered ckt board pads, regournded the boards, swapped tubes, and replaced bypass caps. So far nothing works.

Monitoring the voltage on the grid of V13, as I crank up the RF gain the voltage stays about -1.7 VDC (starting slightly lower, but eventually getting up to that number). About 3/4 of the way thru the rotation of the RF gain pot, suddenly the grid voltage jumps up to -6.5 VDC which is where the audio howl starts in. 

Going on Pin 3 of T-103, with an O-scope, causes the howl to die. Come off that pin and the howl starts up again, although not all at once, but slowly, like it is AGC related. 

Man, I am OUT of ideas. Help!

73  Rich K7SZ

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