That was going to be my suggestion if the HT is dropping a bit more than you'd
expect.
I had the same sort of thing without the HT drop when a painted but not earthed
oil filled capacitor started leaking a tiny bit of static onto the chassis of
the amp. Capacity of the capacitor didn't seem affected, so I just soldered a
good ground to them all and the noise went away.
Can you variac the HT transformer primary up a bit to see if you can re-create
the problem?
cheers
Dave G0OIL
--- On Sat, 6/12/08, n8de@thepoint.net <n8de@thepoint.net> wrote:
> From: n8de@thepoint.net <n8de@thepoint.net>
> Subject: Re: [Amps] rx noise?
> To: "K1TTT" <K1TTT@ARRL.NET>
> Cc: "Amps" <amps@contesting.com>
> Date: Saturday, 6 December, 2008, 5:24 PM
> Dave,
> Sounds like a leaky power supply capacitor. Might be a
> cold solder
> joint in the capacitor chain.
> Good luck
> Don
> N8DE
>
> Quoting K1TTT <K1TTT@ARRL.NET>:
>
> > I have a commander hf-2500 (pair of 3cx800a7's, no
> qsk) that seems to be
> > working fine. However, during cqww cw last week I had
> to pull it off the
> > 20m station because it was making a broadband noise
> while on receive. I put
> > it back on the station today and it isn't doing it
> now. I tried warming it
> > up a bit and it still didn't do it....though its
> obviously not as warmed
> > through as after 40 or so hours of cqww. The only
> other thing I noticed is
> > when it was doing it the plate voltage dropped a bit,
> maybe 50-100v, but I'm
> > not sure if that was a cause or effect since the line
> voltage sag from the
> > other stations can make the hv sag a bit here. Any
> ideas where to start
> > looking??
> >
> >
> > David Robbins K1TTT
> > e-mail: mailto:k1ttt@arrl.net
> > web: http://www.k1ttt.net
> > AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> >
> >
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
>
>
> _______________________________________________
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