Subject: [AMPS] Clipperton-L problems -- need help
>
> 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, 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.
What is the resting plate current, keyed with no drive applied?
> The amp seems to be biased off or the signal doesn't seem to reach the
> cathodes.
If the signal is reaching your watt meter, although less that exciter output,
you have continuity through the amp.
>
> My questions:
> 1. Could the tubes just be bad or shouldn't even bad tubes show more
> current?
A really bad tube will show no current at all!
> 2. Could the .01 caps feeding the input signal be bad?
Not likely, if you have watts coming out of the amp.
> 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?
That is to set the resting (ZSAC) current when the amp is keyed with no drive.
If you have the manual, check what current that is supposed to be, or ask
here on the reflector.
> 5. What should I check next?
We know you need at least one tube...I suggest getting 4; you will probably
solve your problem.
>
> Any help will be g reatly appreciated.
Good luck...report back with findings!
>
> 73, Winston K4CWQ
(((73)))
Phil, K5PC
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