[Amps] Do doorknobs go bad

[Darryl Kwasny]

A couple of years ago I had a problem with my SB-220.  I had a small bang and and got advice from all the experts. I got the suppression kit from Rich and started got that installed. I also had to rework the meter/rectifier board. I got sidetracked by a almost move and set the project aside. Fast forward to now. I just got a new meter/rectifier board from Harbach. Just installed it yesterday. Today I started to do some testing. Without even plugging the amp in I drove it from the exciter. REL PWR responded as it should. 
   
  I then isolated the HV with a rubber eraser, plugged it in and turned the amp on. (no tubes installed yet). Everything went well, about 2.5kv on the meter. Checked filiment volts got about 5.5 (no load. Everything looking good so far. 
   
  Still without tubes installed, removed eraser and turned it on again. A little noise and one of the ckt breakers tripped. After visual check and seeing nothing obvious I then isolated the HV with the eraser, reset the breaker and turned it on again. HV came back up to 2.5kv. Shut it down again, isolated the RF choke and doorknops and checked for grounds. Nothing. Checked the doorknobs to ground, nothing. 
   
  The only thing I have to check the doorknobs is DVM. I checked by the old reverse DVM leads back and forth and get no ohm reading at all.
   
  How can I check to see if one or both  the doorknobs are breaking down. I am at a loss right now. Does it sound like a doorknob is the problem? They are .001 6kv. Any help would be appreciated.
   
  Thanks, Darryl - K5WAS
   
   


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