I acquired this amplifier about two weeks ago, and when I received it,
neither theforward nor reflected power meters would indicate anything. As a
"test", Ireplaced the detector diodes (D114 and D115) with 1N914s as these
were diodes I had on hand. My intent was to see if the meters would at
least register something, and if so, order the correct diodes (1N34s).
Well that worked,so I ordered the diodes.
They arrived, so I replaced the 1N914s with the correct 1N34s. With the
unit all buttoned up again, I noticed while tuning up, the meter lamps
would dim, and the HV would sag significantly. I wanted to test and record
some values when the amp shut down completely; this is what I had to that
point:
HV
(volts) Ig
(mA) Ip
(mA) Standby 3050 0 0 Keyed, no drive 3050 0 0 CW, 5W drive 2700 20 125
I discovered that F101 had blown in the amp. This fuse is in series with
the step start resistor, so it seems my step-start was staying in the "low
current" mode, and when I keyed the amplifier, this 2A fuse blew as
expected. I'm just not sure what broke. The diodes I replaced aren't near
the rectifying diodes that pull the step-start relay. Any insight into
common failures, where to start looking, or how to debug?
Thanks in advance,
John, K8DIL
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