Re: 2101 Pulse gen repair report


Michael Dunn
 
Edited

Thanks Tom, tho, a few notes:

On Fri, Apr 16, 2021 at 05:17 AM, Tom Lee wrote:
For the output amp, the NPNs are 2N3053 and the PNPs are 2N4036, replaceable
here by the venerable 2N2219A and 2N2905, respectively. Those parts are still
available cheaply.
Those parts are for baseline offset, not output amps per se. No AC requirements, so, yes, fairly easily subbed.

To "fix" the output amp, I just removed the offending transistor of the paralleled pair. The remaining part will be fine, as long as I don't push the output too hard.


Q182 is a 2N3563, replaceable by several devices in the 2N918/PN918/2N2857
family.
Which seem to be obsolete, or close enough to :-( At least here, a modern/available SMD could be kluged in if need be (even so, finding one with suitable DC spex may be tricky). I did find a suitable old part in my junk box (2N5179), though its DC specs may be marginal. I hope it lasts.


Be thankful that it's a 25MHz gen, rather than, say, a 100MHz one. You should
be able to find replacement transistors to keep it going pretty much forever.

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