[GreenKeys] Suggestions for RTTY tone decoder

[WA5CAB at cs.com]

CV-89 and CV-89A/URR are part of AN/URA-8A and B.  The Navy made a mistake 
in calling it the URA-8A as there is also the earlier AN/URA-8 where the 
converters are CV-60 and the combiner is CM-14/URA-8.  Less common, but those 
are very similar in appearance and performance to the much more common CV-89 
and CV-89A.  

In the "other" direction is AN/URA-17, which replaced in the Fleet and is 
more or less a solid state version of AN/URA-8B.  All three work quite well 
in either Simplex or Diversity modes.  All are audio types.  And all are 
audio FM types with a discriminator rather than fixed filters.

Another possibility is the R-808/GRC-14.  The receiver is roughly 
equivalent to the Collins R-392/URR except that the R-808 runs off of 115 VAC as well 
as 24 VDC and includes an FSK converter.  The first few hundred built were 
audio converters.  I've never actually seen one.  The majority are IF 
converters.  And with the latter type, there is also the AN/URA-6 IF type using 
CM-14 and two CV-57's or just one CV-57 standalone.

In a message dated 05/01/2017 09:09:44 AM Central Daylight Time, 
duncanancy at earthlink.net writes: 
> Joe,
> 
> The CV-89A is a good FSK decoder. One unit can be used by its self for 
> normal reception/demodulating.  It takes two CV-89As, plus a CM-22A 
> comparator to do diversity.  The HAL ST-6 is a good, solid state, FSK 
> decoder, but will typically only do 850 &/or 170 hz shift. (The CV-89A 

> will do any shift from 10-1000 Hz)
> 
> That being said, there is not much clear-text FSK left on the HF radio 
> bands anymore.  If you just want to decode ITTY, a very simple AFSK  
> decoder can be used, since there is no QRM, fading, etc.  I think there 
> are people on this list who have built them and hopefully they will add 
> their experiences/designs.
> 
> Good luck &Have fun,
> 
> Duncan Brown, K2OEQ
> USASA  31J30
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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