from Tim P (UK)

What was the thinking behind the 'soft' transistor sockets used by
Tektronix in some of the 5000-series 'scopes? I am working on a 5113 / D13
that has these on the storage board. Seems to be a soft white-ish stuff
around the contacts, and it's not clear (to me) if the transistor is making
a good connection.
Also, the lead spacing on the transistor is very slightly different to the
usual T05, meaning a replacement has to be 'jiggled' into it's socket.

regards
Tim

Hi Tim,

This kind of sockets?

https://www.ebay.com/itm/4-Mil-Spec-S-Augat-8058-1G24-1437508-9-4P-PCB-Mount-Teflon-Transistor-Sockets/201234498862?epid=1236928307&;hash=item2eda82c52e:g:d54AAOSw4gpbyhtN

Greetings,

Egge Siert

Hi Egge; no, maybe I didn't explain myself very well - the 'sockets' I
referred to are actually three individual tiny contacts on the PCB into
which the transistor leads go directly. Not an actual socket as we
understand the word ! Imagine a very low-profile socket, but without the
surrounding supporting material, just the contacts.
regards
Tim

This is what you’re referring to:
https://groups.io/g/TekScopes/photo/252113/0?p=Created,,,20,2,0,0

Are these the type that have a sort of rubber grommet at the top that the pin goes through?
-Dave

On 8/15/2020 4:12 PM, Tim Phillips wrote:

Hi Egge; no, maybe I didn't explain myself very well - the 'sockets' I
referred to are actually three individual tiny contacts on the PCB into
which the transistor leads go directly. Not an actual socket as we
understand the word ! Imagine a very low-profile socket, but without the
surrounding supporting material, just the contacts.
regards
Tim


On Sat, 15 Aug 2020 at 20:23, Egge Siert <eggeja2@hotmail.nl> wrote:

Hi Tim,

This kind of sockets?


https://www.ebay.com/itm/4-Mil-Spec-S-Augat-8058-1G24-1437508-9-4P-PCB-Mount-Teflon-Transistor-Sockets/201234498862?epid=1236928307&;hash=item2eda82c52e:g:d54AAOSw4gpbyhtN

Greetings,

Egge Siert

I have used these and I like them except for the fact that they are obscenely expensive at least when I have been able to purchase them.

I have ended up pushing the pins out of machined pin IC sockets and using them instead.

There might be some difference at high frequencies but I will never see it.

-- Bert

The thinking was:

... transistors are expensive, very variable in their gain
from one example to the next, and we are not so convinced
that they are any more reliable than vacuum tubes. So, we
need sockets for the transistors, ... a lot of sockets...
but the available sockets are so expensive, and take up a
lot of room, and are not all that reliable...

The little insert pin sockets that tektronix used are very,
very reliable, and the silicone gasket at their entrance can
take the heat of soldering, and keeps foreign materials out
of the socket... Plus, it adds a little more resistance to
the transistor falling out of the socket.

Tektronix found over time that transistors got cheaper, and
were much more reliable than any sockets you could use to
mount them, so they went to directly soldering the transistors
into the circuit board.

-Chuck Harris

Tim Phillips wrote:

They are miniserts see: < https://groups.io/g/TekScopes/files/Minisert.pdf>;