[GreenKeys] Info needed on CV-278/GR

[Mike]

Thanks Duncan!  Knowing now about the loop current is especially important. I was testing the unit out today on my M28 with loop provided by a HAL TU@ 60mA but only for about 15 minutes so hopefully nothing got toasted.I think I'll instead configure the Mite for internal loop at 20mA.  Mike
-------- Original message --------From: Duncan Brown <duncanancy at earthlink.net> Date: 11/5/22  4:53 PM  (GMT-07:00) To: Mike <mmcauley at cox.net>, Green Keys <greenkeys at mailman.qth.net> Subject: Re: [GreenKeys] Info needed on CV-278/GR 
    Mike,
    
    Rattrig.com has the -20 & -35 CV-278 manuals.
    
    Nothing special to receive 425 Hz shift, just tune it in.  I don't
    remember what the FSK detector bandwidth is or what kind of shape it
    had, but I have copied the German weather station DDK on a CV-278. 
    The schematic shows four tuned circuits in the demodulator, so
    probably pretty wide & linear (for drifting transmitters).
    
    Note that the AN/GRC-46 series ran a 20 ma loop.  I don't know how
    long the keying relay would last at 60ma. Might be alright at 60,
    but best to run it in a 20 ma loop, as designed.
    
    Have fun,
    
    Duncan
    K2OEQ
    
    
    On 05-Nov-22 10:52, Mike wrote:
    
    
      
      Thanks Duncan,  I did look at the rattrig manuals
        but didn't see anything specific for the CV-278. 
      
      
      But knowing that it's 850 shift is helpful, and I
        do have the R-392 to connect to.  How is the switch made to
        convert to 425? 
      
      
      
      
      
      
      
        
        Mike
      
      
      
      
      
        -------- Original message --------
        From: Duncanancy <Duncanancy at earthlink.net> 
        Date: 11/5/22 4:42 AM (GMT-07:00) 
        To: Mike <mmcauley at cox.net>,
          GreenKeys at mailman.qth.net 
        Subject: RE: [GreenKeys] Info needed on CV-278/GR 
        
        
      
      Mike,  
      
      
      It was designed for 850 hz shift and will do 425
        hz shift, but don't know about 170 hz.
      
      
      Takes 455khz IF from R-392 receiver 
      
      
      Have fun
      
      
      Duncan 
      K2OEQ 
      
      
      
      
      
      
      
      
      
        Sent from my
          Kleinschmidt TT-4/TG, the US Army's first portable digital
          communications device, 1950-1980
        
        
        
        
      
      
      
      
      
      
        -------- Original message --------
        From: Mike <mmcauley at cox.net> 
        Date: 11/5/22 01:39 (GMT-05:00) 
        To: GreenKeys at mailman.qth.net 
        Subject: [GreenKeys] Info needed on CV-278/GR 
        
        
      
      Hello group,
      
      
      Recently acquired a CV-278/GR "CONVERTER,
        FREQUENCY SHIFT"
      
      
      All I can find online is a TM maintenance manual
        which is somewhat limited.
      
      
      I'm looking for what the specifications and
        capabilities are for this unit. (Freq, shift, etc)
      
      
      Anyone familiar with it?
      
      
      Thanks...
      
      
      
      
      Mike
      KD7VRG
      Tucson, AZ
      
      
    
    
  

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