Sounds to me like there is a broken connection in the tank circuit. My
guess is that the part of the band switch that connects additional fixed
value capacitors to the Tune and Load variable capacitors is working, but
the connection to the variable Load capacitor and the part of the switch
that shorts out unused turns of the inductor is open circuit somewhere.
Come to think of it, maybe just an open circuit to the loading capacitor
would be enough to cause these symptoms, since there may be no fixed
capacitors added to the loading on any bands besides 80 meters. I would
focus on the connections to the Loading capacitor.
DE N6KB
On Sat, Oct 25, 2025 at 5:11 PM phil greene <trapperpg@gmail.com> wrote:
> New to me Centaur amp with 572 tubes of unknown health.
> Only has output on 80 meters (~500w)
> 10-40 meters have plate and grid current but no output
> Load capacitor has no effect on any band
> Tuning cap will dip grid current
> Tried dummy load with same result
> All resistors check good, and have cleaned band switch and it did not
> appear cracked nor damaged.
> Ideas on where to start troubleshooting?
> N4ZSA
>
>
> Sent from my iPhone
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