[Amps] GE EF-5A VHF Amplifier

RICHARD GEORGE k6kwq at msn.com
Thu Jan 26 14:25:37 EST 2006


Put some back to back diodes on the meter. at least you will save the meter on flash over.


K6KWQ Dick "12 Volt radios are for wimps, real radios can kill you" Still can't make it go QRO with "More Power"
  ----- Original Message ----- 
  From: Xmitters at aol.com<mailto:Xmitters at aol.com> 
  To: amps at contesting.com<mailto:amps at contesting.com> 
  Sent: Thursday, January 26, 2006 10:58 AM
  Subject: [Amps] GE EF-5A VHF Amplifier


  Hello Again :-)

  I have a General Electric EF-5A VHF power amplifier. I think it is Progress 
  Line or Mastr Progress Line vintage, not sure.

  Every one of these amplifiers I have seen at hamfests a few years ago, all 
  had the plate current meter blown open. And with mine, I found out why. As you 
  get close to tuning the thing up, you get a big nasty high voltage bang from 
  inside the unit, the windings on the RF coke on the plate lead get squashed into 
  the center of the RF choke form and quite often, the 4CX250B tube gets 
  damaged. I was very careful to properly neutralize the amplifier and careful not to 
  overdrive the thing. I got to the point where it appeared stable for 10 
  consecutive keyups. OK, I fixed it, so I thought. On the next keyup, she arced over 
  again! I had a simpson panel meter in use to watch the plate current, and that 
  meter just like all the others, blew open.

  So are there any old timers in the group that has some flying time with this 
  amplifier that might know how to calm this thing down? Maybe some 
  strategically placed Zsorb blocks inside the plate cavity? The amp has been in my shack 
  collecting dust, for about ten years because of this issue.

  This really looks like a good amplifier and I have a good supply of 4CX250B 
  pullouts, so I would sure like to fix this amplifier if at all practical to do 
  so.

  And BTW if there are any boat anchor collectors out there that would like to 
  have some GE Progress Line gear, we really need to get together :-) Swap gear 
  for intellectual property maybe? :-D

  Jeff Glass, BSEE CSRE
  WB9ETG since 1970
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