[GreenKeys] SB-2244 and Teletype Synchronous Pulsed Transmission

[Nick England]

Many thanks, Jerry (and others who posted). I'll work out a schematic
of my SB-2244 when I get a chance. I did some quick cleaning and
beeping and it is designed so that loops 1,3,5 are for signals and
loops 2,4,6 are for step pulses - so you could use a double patch cord
to patch both signal and pulse together. The STEP indicator lamps are
driven by little pulse transformers connected to the pulse lines. The
loop current meter says 1,2,3 but actually connects to loops 1,3,5.
More later.....

cheers,
Nick
www.navy-radio.com

On Mon, Jan 4, 2010 at 7:39 PM,  <gfmurphy at earthlink.net> wrote:
>
> Teletype's Synchronous Pulsed Transmission device enabled an external
> device to control the rate at which the keyboard or the TD sent
> information to the signal line.  When a key on a synchro-pulse
> equipped keyboard was depressed, the key latched, the reset bail was
> tripped and a contact closed.  The transmitter clutch was held in
> the unoperated condition until an electrical pulse from an external
> device operated a magnet which released the clutch.  When the clutch
> operated, the transmitting cam rotated and sent the signal information
> to the line. The transmitting cam also moved the reset bail to its
> unoperated position, the depressed key came up and the synchro contact
> opened.  The synchro pulse contact and magnet are in series and they
> are separate from the signal lines.
>     Imagine a simple circuit where one synchro-pulse equipped Teletype
> machine was connected to a communications device that supported the
> synchro-pulse feature.  The communications device could be a
> multiplexor, modem, cryptographic device or whatever. The wiring
> is pretty straight forward: There are 2 signal wires and 2 synchro-
> pulse wires.
>     Now imagine a more complicated arrangement where there are two
> synchro-pulse equipped Teletype machines and two communications devices.
> Let's say that machine A is normally on circuit 1 and machine B is
> normally on circuit 2. In order to move machine A to circuit 2 you
> would plug a patch cord into the SET jack of circuit 1 and plug the
> other end into a looping jack of circuit 2.  However, the synchro-
> pulse leads of machine A are still attached to circuit 1 so you would
> have to move them also.  I believe that this is the purpose of SB-2244.
> It simply allows re-arrangement of the signal loop and the synchro-pulse
> loop.  There must have been some patching rules because you could not
> have the synchro-pulse leads of 2 machines in series.  (They would work
> if they were in parallel.)
>     My thoughts on the operation of SB-2244 are somewhat speculative
> since I've only seen a picture of one.  I am familiar with the SB-1203
> and SB-1210.  A better understanding of SB-2244 could be achieved by
> examining its wiring.  Synchro-pulse equipped keyboards could have the
> feature disabled by moving a clip into position so that the magnet was
> in the operated position.  Every synchro-pulse equipped keyboard that
> I saw on every Navy Model 28 had the feature disabled.  Maybe that's
> why I never saw a SB-2244.
> Regards, Jerry Murphy
>
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