I had one bad tube in my Centurion that caused that condition.
Andy...W3LI
________________________________
Don't do that for a long time. The output matching network is designed for
the plate impedance of two tubes in parallel, which is one half the
impedance of only one tube. The variable capacitors in the Pi network
probably have enough adjustment range to work at either impedance on the
higher bands, but maybe not on the lower bands.
DE N6KB
On Fri, Mar 9, 2018 at 8:58 AM, Mike Schatzberg <
cherokeehillfarm@earthlink.net> wrote:
> You can remove one tube, greatly reduce drive, and see if there is any
> output. Make sure the anode cap from the removed tube is clear of
> everything near it and not shorted. Replace all safety screening.
>
> You can test both tubes, one at a time.
>
> 73,
>
> Mike
> W2AJI
>
> Sent from my iPhone
>
> > On Mar 9, 2018, at 12:48 PM, Stan Gammons <s_gammons@charter.net> wrote:
> >
> > Sounds like one of tubes shorted. If they are still under warranty, I'd
> contact RF Parts and see what they say. They replaced a tube I had that
> shorted.
> >
> >
> > 73
> >
> > Stan
> > KM4HQE
> >
> >
> >> On March 9, 2018 11:11:45 AM CST, Bob <w3hkk@roadrunner.com> wrote:
> >> Bought this used from an estate sale in 2014. Worked great for 3
> >> yrs. Then a tube short blew a fuse. Replaced both finals and all was
> >> well until a few months ago. The amp worked well for a few
> >> transmissions, then the output went to zero. After a few cycles of
> >> this I noticed the grid current which rested at zero began to migrate
> >> negative. As it got worse, the output dropped to nil.
> >>
> >> One suggestion was that one of my new tubes ( from RF parts) is
> >> failing. Another was a possible problem in the AGC circuit.
> >>
> >> Other suggestions? Also, I may need a repair tech and don’t want to
> >> ship the amp, so someone in Ohio or driving distance from central OH
> >> would be a plus.
> >>
> >> Thanks.
> >>
> >> Sent from Mail for Windows 10
> >>
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