[GreenKeys] 7.42 vs. 7.0 machines/

[Nick England]

Yes at some point, many of the Navy's M28 machines came in both 7.00 and
7.42 versions - I don't know why unless it had something to do with some
piece of crypto gear??

If you have sync pulse transmission, I think it is a sure bet that was a
military machine. Did anyone else use that, Jim?

Nick England K4NYW
www.navy-radio.com


On Sun, Dec 2, 2018 at 4:03 PM W9DDD <w9ddd at tapr.org> wrote:

> OK, I kind of had the impression that 7.0 28 was military since the
> keyboard had RFI filtering and a Synchronous Pulsed Transmission
> solenoid and aux contact (crypto machine?).  I suppose business machine
> interface as well?
>
> The printer turned out to be weird (to me) also.  I've seen loaded stunt
> boxes with auxiliary connectors before that sit next to the regular
> connector.  This one has just a 35 pin connector and the selector
> magnets are wired to it along with the plethora of stunt box stuff.  I
> actually found the WD for this one. Selector magnets wired in parallel
> at the printer instead of on the A strip.
>
> Since I found information on both of these in NAVSHIPS instead of BSPs,
> I leapt to the assumption they were military.  The cabinet also was only
> found in the NAVSIPS.
>
> I guess checking the keyboard driving gear on the printer main shaft
> will tell me the full story.
>
> I am able figure out some of the features from the number plates.
> Things like type box arrangements and stunt box arrangements are listed,
>   but it takes some detective work to figure out what those parts in
> those slots actually do.
>
> The WU machine has a different ESU.  My guess after reading what WU WDs
> are available is that it might be a 9100 wiring cabinet?
>
> John, W9DDD
>
> On 12/2/2018 2:21 PM, Jim Haynes wrote:
> > In a recent posting I told the origin of 7.42, it being a design sort-of
> > flaw in a Western Electric printing telegraph.  Morkrum could do 7.00
> code
> > from the beginning, but the Bell System required 7.42 for
> interoperability
> > with the earlier W.E. machines.
> >
> > Western Union always liked 7.00 code and bought most of their machines
> > that way.  Bell System and the U.S. military and other non-W.U. customers
> > got 7.42 from Teletype.
> >
> > Teletype printers can receive 7.00 code just fine, at full speed as it
> > comes from a tape transmitter.  That's because in Teletype design the
> > receiving shaft completes its rotation in time to latch up the clutch
> > even if the stop pulse is only one unit long.  With 7.42 it just rests
> > a little longer.  I believe this is true even for the Model 32, but
> > don't hold me to that.  I don't know that much about the 32/33 line.
> >
> > A 7.00 keyboard requires a different cam and gearing from the 7.42
> > because the keyboard shaft has to turn faster in 7.00.
> >
> >
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