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@aol.com<mailto:Xmitters@aol.com>
To: amps@contesting.com<mailto:amps@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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