Detector Tube Diode Replacement - Printable Version

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+--- Thread: Detector Tube Diode Replacement (/showthread.php?tid=26356)

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Detector Tube Diode Replacement - dconant - 03-14-2026

Hello, I'd like to try and replace the detector section of the 75 tube in my Philco 89. Just want to see if it sounds any different. I have heard that it might have a better sound. Can someone explain how to do that and what diode would work?

Thanks,
Dan

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RE: Detector Tube Diode Replacement - RodB - 03-14-2026

I bought a "working" Philco 650 chassis for my restore because it was recapped, came with a set of tubes, has a good interstage audio transformer and was much cleaner than the one in the cabinet. But when I tipped it over I was surprised to see a pair of 1N4148 signal diodes wired in place of the detector. It probably needed only one as they are tied together.

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RE: Detector Tube Diode Replacement - morzh - 03-14-2026

No, no, 1N4148 are good for some small thingies like 80jr.

For a 650 you need these:

Two of them in parallel will just suffice

   

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RE: Detector Tube Diode Replacement - RodB - 03-14-2026

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