[Milsurplus] Early silicon transistor failures

[mstangelo at comcast.net]

Jim,

I am curious how they work out in case I have to repair vintage solid state in the future.

73 Mike N2MS

> On 12/22/2023 12:29 PM EST Jim Whartenby via Milsurplus <milsurplus at mailman.qth.net> wrote:
> 
> 
> Mike
> Thanks for the info. Have a bunch of 2N4400 on order so I will hold off buying other types until I can evaluate these.
> 
> Found the enclosed document that may allow one to reduce hFE without killing the device. More things to experiment with!
> Regards,
> Jim
> 
> Logic: Method used to arrive at the wrong conclusion, with confidence. Murphy
> 
> 
> On Friday, December 22, 2023 at 09:19:44 AM CST, mstangelo at comcast.net <mstangelo at comcast.net> wrote:
> 
> 
> Jim,
> 
> I saw this add today in Electronic Goldmine. Have you tried 2N3903 the lower gain version of the popular 2N3904?
> 
> <https://theelectronicgoldmine.com/products/g26902?mc_cid=a7184dc10f&mc_eid=9999d432a7>
> 
> 73 Mike N2MS
> 
> 
> > On 12/21/2023 11:45 AM EST Jim Whartenby via Milsurplus <milsurplus at mailman.qth.net> wrote:
> > 
> > 
> > Ray
> > The 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