[GreenKeys] R-808 military receiver with built in TTY

[WA5CAB at cs.com]

Both the AF and the IF converters that were used in the R-808 are FM types 
(use a discrimation instead of two filters).  Although the manual on the 
R-808 never specifies either a shift or specifically expected audio frequencies 
or IF frequencies, probably it was assumed that the nominal shift would be 
850 CPS.  But the discriminators are peaked up for 1 KC total shift.  In the 
audio converter, the center frequency is 2500 CPS with the other two 
frequencies being 2000 and 3000 CPS.  According to the Theory of Operation 
section, the IF unit is centered at 455 KC with the other two frequencies being 
above or below that but the manual never identifies how much.  

In any case, both units will work with 850 CPS shift.  They will continue 
to work as the shift is reduced (keeping the center frequency the same) but I 
can't say anything about performance versus atmospheric noise at reduced 
shifts as although I have owned several R-808's, I never lit most of them off 
and the one that I did, I didn't use on RATT.

In a message dated 10/12/2015 10:56:01 AM Central Daylight Time, 
w2hx at w2hx.com writes: 
> Would it be correct to assume that the R-808 is set up for 850 Hz shift?
> 
> 73 Eugene W2HX
> 
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