Very good advice! However, I doubt that the fixed output caps are actually
doorknobs. Probably disc ceramics as the schematic calls for one to be 430
pf @ 2KV and the other being 330 pf @ 2KV. It appears that the output
loading variable is 800 pf. I haven't looked inside my amp in years. It
just keeps on putting out lotsa' RF when called upon to do so.
73
Bob, K4TAX
----- Original Message -----
From: "Ken Brown" <ken.d.brown@verizon.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, June 20, 2005 11:05 PM
Subject: Re: [TenTec] Centurion loading
Hi Mike,
Highest output
is still obtained with the Load control on 10.
Most amplifiers do not have enough capacitance in their variable loading
capacitor to operate much lower than on about 14 MHz. Fixed capacitors
are switched in parallel for the lower bands. An air variable of high
enough capacity to work on 160 or 80 meters, without paralleling some
fixed capacitors, would be huge, and the amplifier cabinet would have to
be much larger to accomodate it. My guess is that in your amplifier one
of the fixed capacitors that should be paralleled with the variable
loading capacitor has failed, become disconnected, or changed value, so
that when you're on 80 meters, your pi-net really does not have enough
loading capacitance. Could be a burned contact in the band switch or a
loose screw terminal on a doorknob capacitor.
Disconnect all power and short the HV to ground before checking it out.
DE N6KB
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