Replace a Crystal Diode

[Winky Dink]

I pulled out a Heathkit T-4 Signal Tracer which was almost-restored six years ago. I did all of the electronic restoration except for the signal probe which I found confusing at that time. The T-4 detects RF and audio, has a noise-locating function, and can be used as a substitute speaker. This is the first time I've had any practical use for it.




I went over every step in the assembly manual and found no problems until I got to the probe. Here is the electronics in the probe. Sometimes the simplest things confuse me and I need to make a physical real-world drawing to understand the schematic. Here I just modified a Heathkit image of the probe's terminal plate. Yes, it was miswired and the yellow arrow shows where that conduction should go. A should go to C instead of B.



Link to Flickr photo: https://flic.kr/p/2o3Z5ZG

Incidentally, when I desoldered and untwisted the leads it was apparent that it had originally wired correctly. So, the leads from the capacitor and crystal diode have been twisted, soldered, desoldered, untwisted, soldered, desoldered, untwisted, and need to be soldered and twisted one more time. I want to replace them because of the possibility of having an undetected break in the leads.

The .001 disk cap is not a problem, but I don't kknow anything about diodes. (Except that they can be really bad if you put them in backwards.) So, I have diodes 1N401, -4002, -4004, -4005, -4007, 1N5399, and NTE125.

QUESTION: Can I use one of those to replace the crystal diode?

Thanks, Henry.