VCCA Home Forums TECHNICAL - GENERAL Radios, Tools, Accessories 1939 Chevy Radio thump noise

I have a radio in my 1939 Chevy. Actually I think it's from a 1938, because the dial is round instead of rectangle. Anyway, I have taken the time to replace all the capacitors in the radio and now the radio works great. I had it on my bench for a month or so, listening most every day. No problems at all. I installed the radio in the car and it works, but when the car hits a small bump (or larger), the radio makes a loud thump sound. I'm thinking that to find this noise I'll have to tap the radio in a bunch of places and listen. Does anyone have an idea about this noise. Could it be a loose connection between the control head, speaker and/or tube box? Could it be a tube where one of the grids is loose and bouncing a little? Any ideas? Thanks Mike

Antenna ground or lead connections?

I've been thumping a number of things on the radio and I think I have the problem, but not the solution. Seems that the variable capacitor, the tuner is the problem. Have not verified it yet, but I think that one of the plates must be bent enough so that when I'm tuned to the low end of the band 620KC the problem is the worst. Plate mostly meshed. Yet when tuned to the top of the band 1250KC, plates not meshed, the problem is hardly there. Also when I lightly tap the tuner I get the same noise. So I think that I'll have to remove the radio and work on it on the bench. I figure I'll slip some paper strips into each set of plates and hopefully I'll find it that way. Mike