[TenTec] Centurion Plate Capacitor

[Dr. Gerald N. Johnson]

On Sun, 2008-01-27 at 07:19 -0600, atrampler at att.net wrote:
> I'm having some recurring arcing on my Centurion whether in to dummy load or antenna.  I think the plates may have been pitted when I got it as it happens so easily.
> 
> As noted in the Subject Line, it is a Centurion.
> 
> Have any of you replaced the plate capacitor, and if so, did you use Ten Tec OEM spec part or find something with a higher voltage rating?  Any of you ever put in a vacuum variable instead?
> 
I think these days that Tentec made the capacitor. In ages past, there
were tables of voltage rating vs plate spacing in ARRL handbooks.

> Finally, does anybody know what the voltage rating of the plate capacitor is?
> 
> I find that even into a dummy load I wind up giving the amplifier full load capacitance, which is not what the manual expects.  Anyone else have similar experience?
> 
That sounds like showing a high input impedance to the output tank and
that leads to extra high voltage.

You may find it tunes better by tuning for maximum output, not by plate
an grid currents. I had that experience at a MARS station once. The
sergeant had tuned the amp by plate and grid current and the output
(Henry 2K3) was only double that of the exciter. One night was there to
run one of the stations in my weekly sked with my dad (K0CPN) but it was
broken and the main station with the new Henry amplifier that was used
two shifts a day for patches from Nam was quiet because their bands were
dead. So I elbowed the military operators aside and took over that rig.
Had to back off the drive to keep the output down to 1.5 KW. 

I was late getting to bed that night because I had to make them a new
tuning chart based on tuning for maximum output. The next day they
reported Nam said, "I see you finally got the final turned on." So it
did make a difference.

Try tuning for maximum output and the tuning positions may come closer
to those predicted by the manual.

> Toying with sending it to Sevierville, but not yet convinced.  All feedback appreciated.
> 
> 73,
> Art, KØRO
> _
-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer