[Milsurplus] Early silicon transistor failures

[Bob kb8tq]

Hi

There are a lot of components out there that require a pretty good “seal” on the package to keep out the atmosphere. Back in the day, some folks did a better job on packages than others. That said, they all probably leak at some rate. Get enough air in this part (like a vacuum sealed crystal) and you see a big impact. Get enough moisture in by this or that transistor, stuff corrodes, specs change. Have this or that brand of memory chip from “those years" and the moisture pretty much kills them dead X years later. 

Nothing lasts forever ….

Bob

> On Dec 21, 2023, at 10:43 AM, 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
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
> Please help support this email list: http://www.qsl.net/donate.html

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20231221/fc85286a/attachment-0001.html>