[GreenKeys] Why and When 7.00 vs. 7.42 unit code?

[Jim Plummer]

I'll add some fodder the mystery...
While stationed at Andersen AFB, Guam (1958 Comm), we did a modification to the AN/FGC-25's to add a stepper function.  This changed the nomenclature to AN/FCG - 52... as I recall.  This allowed the KLI gear to synchronize with the crypto equipment (so I was told).  The crypto equipment was KW-7 and KW26.  Being 19 years old at the time, TTY was my job not a passion.  So I just install the mods and then headed to the beach.  These modifications included  a couple of gears and a stepper box for the TD.  There may have been other changes that I don't recall.  The year was '66 or '67.... a lifetime ago.   

de Jim 




On Monday, March 10, 2014 9:41 AM, Duncan Brown <duncanancy at earthlink.net> wrote:
  
Nick,
>
>I've been wondering about 7.42 vs 7.00. (& 8.00) also.  
>
>US Army Signal Corps (KLI) used both also.  But KW-7 & KW-26
    crypto units worked with 7.42 codes.
>
>Seemingly identical units would be available in both codes under
    different numbers, so it was apparently important to keep them
    separate.  For example, the AN/FGC-25 & -26 (KLI's "ASR") was
    supplied with 7.42 code. But the seemingly identical AN/FGC-52 &
    -68 used 7.00 code from the tape reader and 8.00 code from the
    keyboard.
>
>I always assumed it was some computer equipment that couldn't handle
    a fractional data bit.  Maybe Autodin?? (I believe that Autodin used
    AN/FGC-161, -162 (low level signaling version of the FGC-25)
    machines. But lthe FGC-161 was 7.42 and the FGC-162 used 8.00 from
    the keyboard & 7.00 from the tape reader.)
>
>I would think it would be hard to sync on a 7.00 code??
>
>Another good mystery to work on!!
>
>73,
>
>Duncan
>K2OEQ
>USASA  31J30
>
>
>
>On 10-Mar-14 08:09, Nick England wrote:
> 
>OK, I understand 7.00 unit code means you can run a bit faster, but who used it in practice and in what circumstances? 
>>
>> 
>> I understand WU was all 7.00 - is this right? 
>>
>> 
>>Looking at the Navy's list of TTY units, there were both 7.00 and 7.42 unit machines galore - how was it decided what to use where? Were all on-line crypto machines 7.00 or some systems were 7.42 and some were 7.00? Or what? What about Signal Corps gear? 
>>
>> 
>>Was there just a break and after July 17, 1958 all new Bell installations used 7.00 or whatever? Or was this decided on a case by case basis - and what was the basis? 
>>
>> 
>>Thanks for helping to reduce my confusement.
>> 
>>Nick England K4NYW
>> http://www.navy-radio.com/
>>   
>> 
>>
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