11 Nov
2025
11 Nov
'25
5:56 a.m.
Christian, it seems like your conclusion is correct. These through hole
high speed bipolar saturated switching transistors are no longer made.
Nevertheless they are still available to buy from a range of sources if you
really want them. The prices and quality vary, but I have successfully
bought enough to support my PDP-8/s well into the future. I had to send
back some which were clearly fake and were ordinary small signal amplifier
transistors. So buyers should be aware. Immediately test them after you
receive them.
Tom
On Tue, Nov 11, 2025 at 4:26 PM Christian Corti via cctalk <
cctalk(a)classiccmp.org> wrote:
On Mon, 10 Nov 2025, Bob Rosenbloom wrote:
Would an 2n5771 (or mmbt5771 SMT) work? They are
fast, used in old
frequency
counters, and cheap on eBay.
Probably, but there is the same problem as with the 2N/PN/MMBT3639/3640:
Part is obsolete, "Mouser does not presently sell this product
in your region." and so on.
So my conclusion so far is, there is *no* suitable replacement part that
is still being manufactured.
Christian
On 11/10/2025 10:10 AM, Tom Hunter wrote:
> The PN2369 is very different from the PN3639 or 2N3639 we are trying
to
>> find.
>>
>> Tom
>>
>> On Tue, 11 Nov 2025, 1:31?am Bob Rosenbloom via cctalk,
>> <cctalk(a)classiccmp.org> wrote:
>>
>> On 11/10/2025 12:22 AM, Christian Corti via cctalk wrote:
>> > On Sat, 8 Nov 2025, Tom Hunter wrote:
>> >> I got hold of some MPSH81. Unfortunately they are not a suitable
>> >> substitute
>> >> for a 2N3639 or 2N3640.
>> > [...]
>>
>> It's not too hard to find the plastic versions of the 2N2369, the
>> PN2369.
>> Mouser has them and so does electronic Goldmine.
>>
>> Bob
>>
>> -- Vintage computers and electronics
>> www.dvq.com <http://www.dvq.com>
>> www.tekmuseum.com <http://www.tekmuseum.com>
>> www.decmuseum.org <http://www.decmuseum.org>
>>
>
>
>