p.s. with practice you can clean those relays in about 10 minutes. Leave
the top and bottom covers on, take off the back plate and tilt it back and
you can reach in with medical forceps to clean the contacts. I prefer
alcohol swab pads since its usually just dirt on the rx contacts that causes
me problems.
I have looked a couple times for a vacuum relay that would fit in that space
and run on 12v/120ma max, but haven't found one yet. This one that is my
problem now has the commander 'high speed' switching board, which has 2 spdt
relays in plastic cases instead of the open frame dpdt like the others and I
have never had to clean those contacts. But I don't think they made many of
those boards.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Patrick Egloff
> Sent: Sunday, December 07, 2008 06:36
> To: amps@contesting.com
> Subject: [Amps] Fwd: rx noise?
>
> Hi All,
> I also have an HF2500 amplifier i got second hand years ago.
>
> During the last CQWW CW i had problem with the antenna switching relay. I
> had to open the amp an try to clean this nasty relay.... I did it twice,
> in
> the middle of the battle ! I must change this low quality relay !
>
> My question concerns the HV drop. On my amplifier, the voltage drops a
> lot,
> i can't remember how much but i always thought it was too.
>
> The output power is never over 1300W.
>
> So, my question. How much R power should this amplifier deliver and how
> much HV does it have under load and no load ?
>
> 73, Patrick
>
>
> 2008/12/7 W7RY <w7ry@arrl.net>
>
> I would suspect the HV diodes rather than the filter caps. You did say
> there
> > was plate voltage fluctuations?
> >
> > 73
> > Jim W7RY
> >
> > ----- Original Message -----
> > From: David Robbins K1TTT
> > To: 'Amps'
> > Sent: Saturday, December 06, 2008 3:46 PM
> > Subject: Re: [Amps] rx noise?
> >
> >
> > I really, REALLY hate intermittent problems like this... it wouldn't do
> it
> > cold. So I started warming it up, after 1/2 hour or so I got the
> > transformer up to 225f, the rf deck surface about 150f, the tubes about
> > 130f, the case was nice and toasty... and I got about 15 seconds of
> noise
> > from all of that. It may have been modulated a bit by line voltage
> > fluctuations from the 160m contest op on the next station, but wasn't
> > dependent on it. There was no measurable grid or plate current when it
> > did
> > it. I did get to cycle the stby/op switch a couple times and the noise
> > dropped but didn't go away when I went to stby... so perhaps it could
> be
> > something in the control board oscillating when it hits some particular
> > temperature, but its darn hard to reproduce.
> >
> >
> > David Robbins K1TTT
> > e-mail: mailto:k1ttt@arrl.net
> > web: http://www.k1ttt.net
> > AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> >
> >
> > > -----Original Message-----
> > > From: Joe Subich, W4TV [mailto:w4tv@subich.com]
> > > Sent: Saturday, December 06, 2008 18:54
> > > To: 'K1TTT'
> > > Cc: 'Amps'
> > > Subject: RE: [Amps] rx noise?
> > >
> > >
> > > Check the bias switch (relay, transistor, ?). If cutoff is
> > > not being applied in receive, the tube will generate wideband
> > > noise ("shot" noise).
> > >
> > > 73,
> > >
> > > ... Joe, W4TV
> > >
> > >
> > > > -----Original Message-----
> > > > From: amps-bounces@contesting.com
> > > > [mailto:amps-bounces@contesting.com] On Behalf Of Paul Kraemer
> > > > Sent: Saturday, December 06, 2008 12:57 PM
> > > > To: n8de@thepoint.net; K1TTT
> > > > Cc: Amps
> > > > Subject: Re: [Amps] rx noise?
> > > >
> > > >
> > > > How about from a zener diode in a bias supply.
> > > > They make dandy noise generators and were the source of
> > > > widband rf for the
> > > > old Omega noise bridge. The current to make noise is
> > > > critical, line voltage
> > > > upset could put it at that point?
> > > > Just fuel for thought.
> > > > Paul K0UYA
> > > > ----- Original Message -----
> > > > From: <n8de@thepoint.net>
> > > > To: "K1TTT" <K1TTT@ARRL.NET>
> > > > Cc: "Amps" <amps@contesting.com>
> > > > Sent: Saturday, December 06, 2008 11:24 AM
> > > > Subject: Re: [Amps] rx noise?
> > > >
> > > >
> > > > > 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
> > > > >>
> > > > >>
> > > > >>
> > > > >>
> > > > >> _______________________________________________
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> > > > http://lists.contesting.com/mailman/listinfo/amps
> > > > >>
> > > > >
> > > > >
> > > > >
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> >
> >
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>
>
>
> --
> Patrick Egloff - TK5EP
> email : pegloff@gmail.com
> Web page : http://tk5ep.free.fr
>
>
>
> --
> Patrick Egloff - TK5EP
> email : pegloff@gmail.com
> Web page : http://tk5ep.free.fr
> _______________________________________________
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