[GreenKeys] Two questions

[Randy and Sherry Guttery]

On 6/16/2011 9:54 AM, Rokumon Cat wrote:
> Hi,
>   
> I have two TTY related questions.
>   
> First, what would be a good rack mount, tube (non-solid state) comms receiver for shortwave to be used to receive RTTY? Yes, I know that the Collins R-390 is the cat's meow of radios, but I cannot justify spending four grand on a radio at this time.
Well - it would require making "adapter" brackets to rack 
mount - but a BC-348 (preferably -R or -Q)  is (IMHO) a fair 
to midlin' receiver.  They are certainly affordable - and 
once recapped, etc. are quite competent receivers.
>   
> Second, does anyone know of a tube based AFSK keyer type
One of the more interesting ones (IMHO) is Technical 
Materials TIS-3 (also knows as a TH-39).   You can choose 
several "center" frequencies (1900, 2000, 2550 plus a 
"spare"*) then "dial in" whatever shift you want - from 
12cps to 1000cps.   *The center frequency is chosen by a 
crystal which "beats" with a 200000cps reactance controlled 
oscillator.  The provided crystals are 198100, 198000, and 
197450 (giving the above listed center frequencies). So if 
you wanted a 1000cps center - you'd use a 199000cps crystal 
- feeding an SSB transmitter, then - would enable going from 
CW to FSK without having to retune the transmitter (since 
both CW mode and FSK mode are now at a 1000cps offset).

The TIS-3s are available from time to time on ebay...   
someone here may have a spare they'd be willing to part 
with.  I sold the TIS-3 we got in Guam many years ago - 
regretted it.  Picked up a nice one some time back - it's 
not going anywhere in the foreseeable future (sorry ;>) )...

 > or even just a circuit?
The TIS-3 Navy manual is here - complete with schematics, etc.
http://www.virhistory.com/tmc/tmc_pages/tmc_manuals/manuals_db/military/mtm_an-th-39b-ugt_1_1_65.pdf

I'm sure others will also offer other thoughts on this as 
well...

best regards...

-- 
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
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