[Milsurplus] Early silicon transistor failures

[Jim Whartenby]

RayThe TC-1 found on eBay, see enclosure.  They can be had for under $20.00 with free shipping.  According to YouTube, there are clones out there so examples with the test leads and charger cord appear to be original units.  YMMV
I am working on KWT-6 SMO modules, mostly scrapped circuit boards from SMOs with mechanical problems.  I guess that they were stored outside since they have frozen bearings which I don't care to replace.  You can't save everything although I try my best!
I have been successful using a TI house numbered device found at a Missouri Hamfest years ago.  They are TO-18 devices that are just useable with their 1/2 inch long leads.  They range in current gain from 20 to 80.  So far, devices in the 20 to high 30s range seem to work well.  It is hard to find modern transistors with HFEs that low.  I have ordered 200 each of the 2N4400 devices (datasheet enclosed) as a backup and will try sorting them with the TC-1 for HFE and emitter current.Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 

    On Thursday, December 21, 2023 at 09:43:36 AM CST, Ray Fantini <rafantini at salisbury.edu> wrote:  
 
  
I spent a lot of time working on GRC-106 sets, one of the highest failure rate items 1A3 frequency standard. The 5 MHz oscillator just stops oscillating, no bad components and just doing regular VOM checks of the transistors and they look good.

They use a couple 2N706 NPN silicon devices, one as an oscillator and the second as a buffer. I tried some generic replacements but no love there. Wonder if I need to buy something for reading gain and start looking at that? The data sheet for the 2N706 tells me that the HEF should be 20

What are you using to see HEF?

 

Ray F/KA3EKH
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