Thanks, Carl! The tuning capacitor was *completely* unmeshed and I could
not find the expected "double dip" points, which is what concerned me. I
could never know if I was truly resonant or merely close.
I found a way to get the cover off without removing the amp and allowing
me to spread the 15 m turns a bit. After spreading the 15 m part of the
coil, everything is precisely as I like it. I get full steam out on 15 m
(with ~105 w of drive) and, as expected, run out of drive on 10 m. If I
could drive it hard enough, I'm pretty sure I'd get 1500 W out before I
hit the plate or grid current limits. All this with 4 kV on the plate,
along with the necessary an added capacitor in the HV PS for the extra
voltage and a bit more bias voltage on the grid to set the proper idle
current.
The AL-1200 is nowhere near an Alpha (and far from anything with a
3CX3000A7 in it), but I got it for an excellent deal. I added a QSK-5
internal QSK switch, and replaced all the filter capacitors and bleeder
resistors so my bang-for-the-buck is superb.
Kim N5OP
On 10/18/2014 10:59 AM, Carl wrote:
If the tank is resonating at "almost" unmeshed and there are two
resonance points as you continue the rotation youre fine, leave it alone.
Carl
KM1H
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