Yes, if it's the caps then retuning would bring it back up.
I looked at the pix on your website and I see you have a bunch of 0.01 discs in parallel
in series with the input. There is probably some heat being generated there, since a lot
of current flows. A 0.1 uf transmitting mica would be better. Of course the value isn't
critical, so that might not be the problem.
Regarding your comment about the Shurite meters bouncing: a simple solution is to just put
a capacitor across them to damp them out. I used such meters in one of my first HB
transmitters back in 1957!
On 9/10/2013 6:35 PM, Mike Waters wrote:
Thanks, Vic. Someone else (in a private e-mail) just suggested line voltage. I
do monitor
the filament voltage, but I should monitor the 240 VAC and look at the HV
meter, too.
There is a "too-long" run of #12 from the breaker panel to the amp, and if that
wiring
heats up, that might do it.
As for the pi-net caps, that's what I thought at first. I have padder caps
--some with a
high negative temp coefficient--- on both C1 and C2 in the pi-net output.
However,
re-tuning should compensate for that and bring it back up to full power out
(shouldn't
it?), but it never does.
73, Mike
www.w0btu.com <http://www.w0btu.com>
On Tue, Sep 10, 2013 at 8:29 PM, Vic K2VCO <k2vco.vic@gmail.com
<mailto:k2vco.vic@gmail.com>> wrote:
Does the line voltage droop when you transmit, causing a drop in filament
voltage?
Do you have ceramic capacitors in the tank circuit that heat up and detune
the tank?
On 9/10/2013 6:03 PM, Mike Waters wrote:
`
Anyone have an idea why the power output of my dual parallel 833C 160m
amp
often drops 200+ watts after several seconds? Re-tuning does not bring
it
back up to the initial output.
Not that a drop from 1500 to 1300 watts is a big deal, but inquiring
minds
want to know the reason. :-)
Description:
www.w0btu.com/833C_linear_amplifier.html
<http://www.w0btu.com/833C_linear_amplifier.html>
More photos:
w0btu.com/files/misc/833C_linear_amplifier/?C=M;O=D
<http://w0btu.com/files/misc/833C_linear_amplifier/?C=M;O=D>
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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