[GreenKeys] WU M21-A (was Western Union tape transmitter 22-A by J H Bunnell)

[Cory Heisterkamp]

Anyone have a scan of the schematic? Sounds interesting.... -C

On Mon, Feb 2, 2015 at 10:34 AM, Jim Haynes <jhhaynes at earthlink.net> wrote:

> On Mon, 2 Feb 2015, Jeffrey D Angus wrote:
>
>  On 2/2/2015 9:06 AM, Duncan Brown wrote:
>>
>>>  There is an article in the April 1962 issue of RTTY magazine that has
>>>  an electronic distributor for the WU M21-A.
>>>
>> Oh this is absolutely precious.  24 tubes. It would be even more if it
>> wasn't for the 6SL7 dual triodes and 6H6 dual diodes.
>>
>>  And if you should be so foolish as to attempt to build the circuit...
> There was an error in the schematic - I don't recall offhand if the
> 1962 reprint has it corrected.  Also as I recall W6ZBV later replaced
> the 6V6 and millisec relay with a 2050 thyratron..
>
> I actually built the circuit, but never got it to work.  Didn't know about
> the schematic error.  Was using junk-box pots.  Had no means of testing
> and adjusting.  Well if I had been smarter I could have built a
> multivibrator that would be adjustable to the various pulse lengths,
> but then I didn't have a calibrated triggered sweep scope to set it with.
>
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