[Heath] HV modification of Chippewa KL1

[Glen Zook]

Looking at the schematic (I don't have a KL-1 nor have I worked on one), from Pin-1 of the 4-400A, which is one side of the filament (which is the cathode in the 4-400A), there is a direct connection to ground.  It might be possible to move the meter from the B+ to where this jumper is located.  That is, the ground connection would go through the meter.


You would have to bypass Pin-1 to ground using a capacitor.  Also, a capacitor on the + side of the meter to ground.


In the moved condition, the meter would read cathode current (this is done in most transmitters) which also includes the screen current.  When the KL-1 was made, the regulations were for plate input power and by having the meter directly in the plate line, the reading was more accurate and higher power could be run since the screen current did not have to be estimated.  Today, the regulations are for power output so absolute accuracy of input power is no longer required.

 Glen, K9STH 
Website: http://k9sth.net

      From: John King via Heath <heath at puck.nether.net>
 To: Heathkit List <heath at puck.nether.net> 
 Sent: Sunday, September 9, 2018 12:32 PM
 Subject: [Heath] HV modification of Chippewa KL1
   
Has anyone modified the High Voltage metering circuit of the Heath Chippewa KL1 amplifier to take the HV from direct connection to the HV meter. I am looking for a modification to make the amplifier that I just acquired safer by getting the 3,000 vdc plus off the HV panel meter. Thanks and 73, John, K5PGW
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