Looking for PDP-8 G603 "Memory Selector Matrix" boards (or dec T-2052 transformers)

[Charles Dickman]

Do we know who made the transformers originally? I maintain some old
industrial hardware designs that used pulse transformers from the
mid-60's and I may still have catalogs and/or data sheets.

-chuck


On Thu, Apr 13, 2017 at 7:01 PM, Pete Lancashire via cctalk
<cctalk at classiccmp.org> wrote:
> Using a t-2052 build up a test fixture, a pulse generator and a
> oscilloscope and if have access to one a high bandwidth current probe. Use
> the 2052s you have, record the curves etc and then make up some test
> transformers.
>
> -Pete component engineer in a former life.
>
> On Apr 13, 2017 3:36 PM, "Vincent Slyngstad via cctalk" <
> cctalk at classiccmp.org> wrote:
>
>> I realize it's a long shot, but does anyone have:
>>>
>>
>> - Any spare T-2052s (or know of a source)
>>> - Any idea what the T-2052 *was* so I can try to replace them.  I haven't
>>> found much detail as of yet.
>>>
>>
>> Good news on this front!
>>
>> I had previously obtained a data sheet for the T2037, a similar
>> transformer.
>>
>> I extracted 4 each T2037 and T2052 from a broken G228, and today I was
>> able to get measurements off of them:
>>
>> T2037:
>> A: 230uH, 170 mohm primary, 42.9uH 100 mohm secondary
>> B: 220/170, 41.6/100
>> C: 232/170, 43.8/60
>> D: 231/170, 43/80
>>
>> These are consistent with 16 turns and 7 turns of #33 wire, wound on an
>> FT37-77 toroid per the instructions on the data sheet, and also with the
>> 220 uH /43 uH 20% specs that appear there.
>>
>> Here are the T2052 measurements:
>> A: 597/320, 597/320
>> B: 530/270, 530/270
>> C: 34/1040, 24/680
>> D: 551/280, 551/280
>>
>> Ignoring "C", which is quite likely broken in some way, these are
>> consistent with a 25 turn 1:1 transformer.  I'm not sure what they are
>> wound with, as #33 wire should give a lower DC resistance.
>> (#34 is closer.  It's also possible that they changed cores, but I suspect
>> that they are also wound on FT37-77 cores.)
>>
>> It's possible that a fairly standard modern 1:1 pulse transformer could be
>> substituted.  The 78615/2JC, for instance is 500uH, 1:1 if you ignore the
>> center tap pins.
>>
>>    Vince
>>