What does "I then isolated the HV with a rubber eraser" supposed to mean??
If you are trying to say that you defeated the HV shorting bar with an
eraser then by taking it out you now have a shorted HV and therefore BANG.
Just be lucky the tubes werent installed or you would possibly have taken
out the zener, a grid choke, a resistor and maybe the meter. Many owners
simply bend that bar down and out of the way and then use proper precautions
when working around HV.
The plate doorknobs sometimes break down from RF and overheat and then fail
open; they are not RF rated but Heath was cheap. There is a safety choke
underneath that will supposedly blow if HV gets onto the tank circuit.
Carl
KM1H
----- Original Message -----
From: "Darryl Kwasny" <djkwasny@yahoo.com>
To: <amps@contesting.com>
Sent: Monday, October 15, 2007 11:34 AM
Subject: [Amps] Do doorknobs go bad
>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
>
>
>
>
> Cape Coral Time & Temperature
>
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