[OKDXA] Amp Fixed (I Hope)

[garylm at kiamichiwb.org]

HI KIM, 
Glad you found the problem, I turned my amp on yesterday and it blew incoming voltage fuse on warm-up, hope to find another 250v 20amp fuse tomorrow, hope that is all that is wrong.  Fuses and amp are over 30yrs old.
Sitting here listening on 30m to stations calling FT8WW, but not hearing him here. Looks like this is going to be one I miss.
Good luck working him and the TN8K, he is on 3.525 now but cannot hear them.
73
Gary - WQ5R
 


On Sun, 8 Jan 2023 18:56:05 -0600, Kim Elmore <cw_de_n5op at sbcglobal.net> wrote:

I found that I hadn't escaped the flashover event unscathed: my rx was
dead with the amp enabled . I installed a QSK-5 PIN diode T/R switch in
my amp so that I could do QSK at 1.5 kW. Since I'm not in a multi-multi
environment, I needn't worry about any IMD issues that can occur with
PIN diode T/R switches in high RF environments. The rx path is protected
by two grain-of-wheat bulbs and if the current in the rx path gets more
than a few mA, these blow. They were blown. It's an easy fix.

A careful internal inspection revealed no issues. I hadn't been diligent
at all about cleaning the amp interior the past few years and there was
a fair buildup of dust inside and around the RF deck. I suspect, but
can't prove, that the flashover was caused by dust in and around some of
the HV areas, perhaps near the base of the plate choke. I saw no scorch
marks, so I don't know for certain, but it's all I can come up with.

I did learn that the fuses in the line input to the amp, two 15-ABC
fuses are pretty expensive. But! I found someone selling six 5-packs of
them on e-pay for $1.00 each. So, I got 30 15-ABC fuses for $6 (six
5-packs) plus $8 shipping. These guarantee that I'll never see this
happen again!

I only need to put the cover back on, secure it the 22 4-40 screws, and
I'll be back where I was.with

73 & CU in the Pileups,

Kim N5OP
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