[GreenKeys] synchronous pulse operation of M28

[Nick England]

Just for curiosity's sake I am trying to understand how synchronous pulse
operation was used. I assume that some sort of synchronous crypto gear
required this. Were there other places when it was used?

I can see how a crypto device input would issue a pulse to a TD telling it
exactly when the transmitter clutch should be released and a character
transmitted. And a crypto device output could just drive a reperf directly
with no need for a pulse (assuming the pulse rep rate didn't exceed reperf
cycle speed of course).

But what about a keyboard as input to a crypto device? From what I read,
you press a key but the clutch release is held off until the synchronizing
pulse is received - then the clutch is released and the contacts cycle as
usual. Couldn't this get fumble fingered if you are typing and every now
and then it takes almost 2 character times before the keys are released?
Were you limited to typing at 1/2 the circuit WPM?

As I said, I'm just curious - I haven't found any crypto gear at hamfests...
.
Cheers,
Nick England K4NYW
www.navy-radio.com
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