[Hallicrafters] Feedback problem with SX 99

[jew123 at juno.com]

Feedback problem with SX 99.

On bands two, three and four when I tune in a strong station the radio becomes micro phonic.  Since the radio sets on top of an eighteen-inch tall wooden speaker cabinet there is instant feedback with a low rumble.  I can lightly tap any of the tubes or the tuning capacitor and it is like tapping a microphone.

I have two sets of nos tubes except the 5Y3 and swapped out the tubes but that does not help.  Turning the volume or RF gain way down helps.  I can even tap the cabinet and it will pick it up.  Taking the radio off the speaker cabinet stops the feedback but the radio is still micro phonic.  I have recapped, put in new AC 3-wire line cord and filter caps.  I even repainted the cabinet restrung the dial cords.  All I have for test equipment is a DVM and 20k ohms per volt multi-meter.

I wonder if the radio is haunted?  Any help?

Jim Winkler
Dallas, TX 


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