[600MRG] New transmitting rig for 630-meters

[sbjohnston at aol.com]

I've got my second 630-meter rig operational.  This one takes the DRV signal from the Kenwood TS-990S on 475 kHz and uses an LPB "carrier current" broadcast linear amp to boost it up to 30 watts or so.  Earlier I added a driver stage to the amp using a video op-amp IC to take the 0 dBm from the transceiver DRV jack up to the level the amp was expecting.  

I use an L-network to match the 50 ohm output of the amp to my inverted-L antenna.  I don't know how good the match really is as my spare SWR bridges didn't seem to work - maybe they are limited as to how low in frequency they can be used (never thought about that before).  But there's a combination of settings where the antenna ammeter peaks up very nice to about 1.4 amps.   And the relative output indicator on the amp is at the same value as when the amp is running on a dummy load, so that's a good sign.  

 
Once I confirm the match is decent, I'll see just how linear this setup really is.  If it is linear then I can run data modes from the transceiver, if not then I can run CW and Hellschreiber until I figure out how to make it linear.



Steve WD8DAS / WH2XHY

sbjohnston at aol.com
http://www.wd8das.net/
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        Posted by: sbjohnston at aol.com        
     
    
 
    
      
        
          
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