[GreenKeys] Model 28 Stuntbox fun and games

[Ralph Irish]

Eric & others

There was some reason for the hardware associated with UC H.  There was a method of operating on RTTY
where one station could control the other's transmit/receive function.  Sound interesting?  It was 
commonly referred to as "H Break".  If both stations were so equipped, the sending of Figs-Blank-H
would turn your transmitter off, and un-mute the receiver.  On the other end, it would mute the
receiver and turn the transmitter on.  So, very fast break operation between two stations could take
place.  

Each station had to have their stunt box react to a "Figs-Blank-H" sequence to trip a switch on the
stunt box, which caused all of that activity to take place.  

I wrote an article about this in a RTTY Journal back in early 1983, I think.  My article dealt only
with using the switch closure to operate a special type of relay not part of the machine.  There is
a type of relay called "Wire Spring Relays" which were used in large numbers of telephone switching
systems.  It was possible to use one relay 'frame' that had two individual relays to respond to a
switch closure to bring about the other transmitter/receiver operations.  One of the relay contacts
had to have 'Make Before Break" operation.  With this, two of the relays could be wired together to
respond to the switch closure and change state with each closure.  (Type AK-4 and others, I think.)

A "Figs-Blank-H" sequence, whether it came from your keyboard or from the distant station's sending
caused this action to take place.

Many different ways of accomplishing the transmitter and receiver operations could be devised, but
it all worked back to the switch closure when the sequence of "Figs-Blank-H" came in.  That sequence
was not likely to occur in casual text or ordinary operation of a station,  AND  this "H-Break" idea
could be defeated with a switch somewhere on one's station controls.

I wish you continued success in your discovery and operation of the Model 28.

73,

Ralph - W8ROI

PS   If you go looking for that article in RTTY Journals, my call then was WA8GDT.

R

- - - - - - - -

On Sep 1, 2017, at 7:22 PM, Eric NO3M wrote:

> Thanks for all the comments.
> 
> I got a little ambitious this afternoon following my post earlier and starting tearing away at the stunt box.  Its been quite interesting pouring over the old bulletins, diagrams, and the W6FFC (Hoff) article series that ran in the RTTY Journal from the early 70s.
> 
> I basically removed all the switches, function bars, function pawls, and associated springs from the stunt box except for slots 1,2,3,4,5,39, and 40.  All parts are bagged and stored in a box inside the compartment below the printer.
> 
> Slots 1,2,3,4,5 and 39 were left as-is (4 and 39 is the end-of-line auto-CRLF).  Had to adjust the right margin ring on the spacing drum to get 73 character auto-CRLF, was doing 78.
> 
> I took one of the universal function bars and snapped off tines to make another CR function bar.  That was installed in slot 40 replacing the original LF function bar.  I moved the original LF bar to slot 30 which has a function lever that engages the space suppression bar.
> 
> So far, with some limited on-air reception, it is working great.  A received CR results in a CR-LF action and a received LF does nothing.  Clearing out all the other slots also got rid of the multiple blank locks keyboard stuff and also restored the shift-H (#) behavior.  Originally there was space suppression on the (#) character.
> 
> Jeff: I look forward to seeing the information you gather about the various logger behaviors.  It would be useful to know what to expect, hopefully CR=CRLF and LF=null is sufficient.
> 
> Jerry: I am not experiencing the double line problem you mentioned by putting a CR function bar in slot 40.  The spacing correctly corresponds with the single-double LF lever setting.  Thanks for all the information regarding the various part numbers and kits.  I'll archive that info for sure.
> 
> 73 Eric NO3M
> 
> 
> 
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