Shorted tube. Grid to cathode (filament).
Thanks
73
Jim W7RY
On 3/18/2020 10:33 AM, Mark - N5OT wrote:
Hello [Amps] Gurus,
I had a failure of my Henry 2K-4. I am betting it is a well-known
failure mode, and that multiple people on here, after hearing a
description of what happened, will be able to tell me what happened.
I am operating a contest. SSB. I notice there is no output on my
power meter. I look at the amp. The meters are not moving when I
talk. But the tubes are glowing orange quite nicely. Like ... TOO
nicely.
The tubes are glowing so bright orange - I know something is VERY
wrong. I wasn't transmitting. I could not make it stop. I pulled
the TR relay control cable. No change. Nothing I tried got this
situation to change. I shut off the amp's power switch and let
everything cool down (a very bad feeling to turn off both the glowing
tubes and the blower too - ugh).
At that time, with zero drive, not in transmit mode, not key down, the
meters read like this:
Plate current = 400ma
Grid current = pinned negative
I messed with the power switch and the breaker and the relay and the
bandswitch and - honestly I was baffled and not being methodical at
all - and after some "messing" the amp started working again.
Then a short time later it happened again, but since I was keeping a
very close eye on it, I shut it off immediately.
Then it started working again.
Then finally it failed again and it has stayed failed.
So ... my guess is, youall having a very large amount of knowledge and
experience, you can probably tell me which relay has failed or which
capacitor or resistor became intermittent then failed. Or if it's a
tube that shorted or something like that.
Thanks in advance.
Mark N5OT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|