Date: Thu, 23 Dec 2010 15:29:08 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: [Amps] TenTec Centurion - 422 tuning question
On 12/23/2010 2:53 PM, Alek Petkovic wrote:
> Confusing indeed. I noticed the same thing with the Emtron DX-2SP at
> my club. Turning the knob to the right increases capacitance.
This seems to be the way Ten Tec power amps are set up. My Titans,
vintage 1980, are also set up that way.
n 12/23/2010 2:46 PM, Gudguyham@aol.com wrote:
> I am still confused about 10 being full capacity. The dial could have
> been put on wrong.
So take the cover off and look at it! That's what I did. End of
confusion. :)
It's also quite easy to change, simply by taking the knob off and
re-seating to zero at max capacity. Now capacitance will be minimum at 10.
## Correct. I have seen this same error on a few HB amps as well.
With the load at '0'... the load cap should be fully meshed. And
min C when at '10'. Turning the load CW should Decrease C.
When you increase the loading you are decreasing the load C.
## I worked on a buddy's centurion years ago [one bad tube had a grid to
cathode short, which caused both tubes to run bright orange.] When the
centurion 1st came out... it sucked normal idle current...on RX !! They all
did that.
Apparently ten tec didn't figure out that the tubes are supposed to be cut off
on RX.
## I also noticed on my buddy's centurion, that the loading control is real
sluggish..
but only on 160m [dummy load]. If you look at [ and measure] the tune, load
and
coil for 160m, it's obvious that they run it at a real low loaded Q on 160m.
Being a
simple PI net, they used a smaller than normal tune cap... and bigger than
normal coil.
That way they didn't have to pad the tune cap... yet it had a low enough min C
to work on 10m...barely.
Having said that, I have noticed this same sluggishness on HB
amps..again,only on 160m..
and that's with a normal Q, or even with the loaded Q a tiny bit on the
higher side of normal.
By sluggish, I mean the load control tunes real broad vs the external
wattmeter.
Jim VE7RF
It's also important to realize that a pi-network is an impedance
matching network. So changing the value of the capacitors changes the
match between the output impedance of the tubes and the connected
transmission line.
73, Jim K9YC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|