[Amps] Internal QSK-5

[Phil Clements]

> Subject: [Amps] Internal QSK-5
> 
> I have an AL80A with an internal QSK 5 switch (one of the early ones)
> that I've had since new (S/N 095). For well over 20 years, it's been
> working flawlessly. Recently, though, I had some 160 m antenna
> problems under high power and blew the fuse lamps that protect the rx
> PIN diodes. Blowing these is no biggie as it's happened before when I
> mis-selected an antenna or has a switch set wrong. I replace them and
> go on my merry way.
> 
> WIth K3LR's help, may 160 m antenna seems to be going again. So, as a
> final smoke test, I stated testing it under high power. But, this
> time I'm seeing the fuse lamps light up when I transmit with more
> that a few hundred watts on 160 m into a dummy load. I don't see this
> on 80 m or any of the higher frequencies. As far as I know, this is
> new, though I've never had much of a 160 m antenna and so didn't use
> the amp it much down there.
> 
> I'll check the schematic, but does anyone have an idea or two about
> what might be going on?


On page 5 of the QSK-5 manual, it tell exactly what is going on, and how to
do a couple of tests to see what the problem(s) may be.

What they do not mention is that if your problem is only on 160 meters, RF
may be getting into the QSK-5 from the cables coming into the box. Some
ferrites on the incoming lines should cure this, if your tests conducted
from the manual show no faults.

I have been a proud owner of a QSK-5 since 1999. I have used it at maximum
rated power and also mobile, running a KW.

(((73)))
Phil, K5PC