When the exciter is keyed, but with no drive, the reading on the Clipperton
is about 50 mills.
Winston K4CWQ
----- Original Message -----
From: KB7WW Art Moe <kb7ww@chatusa.com>
To: Winston F. Jones <winjones@ix.netcom.com>
Cc: <amps@contesting.com>
Sent: Tuesday, September 05, 2000 01:07 AM
Subject: Re: [AMPS] Clipperton-L problems -- need help
>
>
>
> "Winston F. Jones" wrote:
> >
> > I recently bought (as-is) an old Dentron Clipperton-L amp, early model
> > (serial #0906) without tuned inputs. The person I bought it from said it
has
> > been sitting on a shelf for several years unused. He said when last
tried,
> > it put out about 600-700 watts, using the three 572B tubes which are in
it.
> > (The fourth tube had a bad filament and he removed it.)
> >
> > After I received the amp, I hooked it up. Everything lights up. The
panel
> > voltage meter reads correct volts-- about 1,800 in CW position and 2,700
in
> > SSB. When I flip switch to operate and activate my exciter, the relay
clicks
> > and the red light comes on,
>
>
>
> At this point what is the plate current reading? That is with the
> exciter / amp keyed, but with no output from the exciter.
>
>
>
>
>
> >but very little RF comes out of the amp, no
> > matter how I tune it. My watt meter shows about half what the exciter is
> > sending barefoot. The Clipperton current meter shows only about 50
mills of
> > current. I would expect the current to be 400-500 mills, even with just
> > three tubes. On SSB, the amp meter does bounce a little with modulation,
but
> > the power is less than barefoot strength.
> >
> > I checked all connections inside the amp. Nothing smelled burned. Using
an
> > ohmmeter, the B-plus line seems O.K. from the power supply to the plate
caps
> > of the 572B tubes. I didn't check voltage with amp running. I'm too big
a
> > coward for that and I don't trust my voltmeter lead insulation.
> >
> > The amp seems to be biased off or the signal doesn't seem to reach the
> > cathodes.
> >
> > My questions:
> > 1. Could the tubes just be bad or shouldn't even bad tubes show more
> > current?
> > 2. Could the .01 caps feeding the input signal be bad?
> > 3. My instruction book refers to a matching network in the parts list,
but
> > the input in my amp goes directly through .01 caps to the filaments.
> > 4. What is the purpose of the 9.1 volt, 50-watt zener and could it be
the
> > problem?
> > 5. What should I check next?
> >
> > Any help will be g reatly appreciated.
> >
> > 73, Winston K4CWQ
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/amps
> > Submissions: amps@contesting.com
> > Administrative requests: amps-REQUEST@contesting.com
> > Problems: owner-amps@contesting.com
>
> --
> FAQ on WWW: http://www.contesting.com/FAQ/amps
> Submissions: amps@contesting.com
> Administrative requests: amps-REQUEST@contesting.com
> Problems: owner-amps@contesting.com
>
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|