Re: Model 20 Modification - Printable Version

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Re: Model 20 Modification - Guest - 03-03-2007

I am in the process of restoring a Model 20. This radio works, but has an odd modification which am trying to un-modify. The radio as built should have had a 27 af tube feeding two 71A's in a push-pull configuration, through an interstage transformer. This was modified in the following ways: the 27 was replaced by a 47 and feeds the speaker directly. The 71A's were removed, as was the interstage transformer. I am wondering if anyone has seen this type of mod? Looks like it was done some time ago. The radio does function this way. Unfortunately the tube sockets for the 71A's have been removed and the tubes physically replaced with metal can caps. I haven't traced all the wiring yet, but I suppose these are being used to bypass the original filter caps. The speaker was also replaced - with an old Jensen field coil speaker. Has anyone else seen such a modification?
Thanks

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- Ron Ramirez - 05-26-2007

Certainly NOT a factory mod. Your radio has lost a stage of audio amplification by using a 47 in place of the 27 audio amp and not using the push pull 71As at all.

You could always convert it back by adding two 4 pin tube sockets where the hole covers are now at...as well as an interstage transformer, push-pull output transformer, 71A tubes, a 27 tube, undoing the modified wiring, etc.

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