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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