[AMPS] Clipperton-L problems -- need help
Winston F. Jones
Mon, 4 Sep 2000 14:27:00 -0000
When the exciter is keyed, but with no drive, the reading on the Clipperton
is about 50 mills.
----- Original Message -----
From: KB7WW Art Moe <firstname.lastname@example.org>
To: Winston F. Jones <email@example.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
> > been sitting on a shelf for several years unused. He said when last
> > it put out about 600-700 watts, using the three 572B tubes which are in
> > (The fourth tube had a bad filament and he removed it.)
> > After I received the amp, I hooked it up. Everything lights up. The
> > voltage meter reads correct volts-- about 1,800 in CW position and 2,700
> > SSB. When I flip switch to operate and activate my exciter, the relay
> > 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
> > 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,
> > the power is less than barefoot strength.
> > I checked all connections inside the amp. Nothing smelled burned. Using
> > ohmmeter, the B-plus line seems O.K. from the power supply to the plate
> > of the 572B tubes. I didn't check voltage with amp running. I'm too big
> > 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,
> > 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
> > problem?
> > 5. What should I check next?
> > Any help will be g reatly appreciated.
> > 73, Winston K4CWQ
> > --
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