That's about right for one of these amps.
If they have not been changed you might want to replace the caps,
bleeders and diodes on the PS as those
are the weak points in this nearly 30 y/o amp and all these components
degrade over time.
Other than that it is a bulletproof amp. Bruce Alexander designed a
real gem when he put this amp out.
The previous owner may have thought the tubes were soft due to a
overloaded or undervoltage AC
mains input which would affect HV and power output
Ron Hauser wrote:
> Greetings QRO afcionados. I got a "good deal" on a Dentron Clipperton L,
> which is my first amp, so I have some questions.
>
> 1) When all tuned up, and keyed in SSB with no mike audio, I believe I
> should see some idle bias plate current. Without even thinking about this,
> my old kenwood tube final radio has 60 ma idle bias, so I would expect more
> for the amp. I have very little, like 50ma, barely bumping the needle.
> Does a grounded grid amplifier use plate idle bias current? How much should
> there be, and how would I adjust?
>
> 2) One of the reasons that this amp appeared to be a "good deal" is because
> it was sold with the presumption of soft tubes, thought to be a good amp
> needing tubes. I understand from reading the manual that this amp is
> designed for 1 kw DC input, and in the CW position I get right at 1 kw in,
> and 600 w out. Switching to SSB position and keying down very briefly, I
> get 1000w. I feel pretty good about this, would you call these soft tubes?
>
>
> Background: I got licensed about three years ago and have really fallen in
> love with the old Kenwood tube final radios. My main radio is a TS830 that
> I have babied and modified. During the course of learning how to work on
> these old kenwoods, I have learned _a_few_ things about tubes, keep your
> fingers out of the HV and keep one hand in your pocket, etc. I'm not an
> electrical engineer (though I am a chemical engineer) so I haven't worked on
> electronics before getting into ham radio. So I know enough to be
> dangerous.
>
> The amp has been hooked up since christmas, it is on a dedicated 220v
> circuit that has about 240-245V. I get 1850V in CW position, 2600V in SSB
> with pretty small sagging during key down. The antenna is a 140 ft doublet
> fed with window line from a tentec 2kw tuner. Nearly all the operating has
> been on 80m, with a handful of contacts on 20m. No attempts at other bands
> yet. I have seen the web pages about improving the performance on 160m, but
> for now I don't have an antenna for that band.
>
> I've gotten good reports, including getting on the air locally with a friend
> who knows me and my voice, and we went back and forth to compare. So I have
> no complaints, if it ain't broke I don't want to fix it, but since I am new
> to amps I just wanted to confirm.
>
> Thanks!
> --Ron
> K0EIA
>
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>
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