[TenTec] Centurion Amp QSK Board

[bcarling at cfl.rr.com]

Thanks Bob - my 422 cebnturion is all fixed and working 100% now.

First I installed the newly rewound plate transformer from Gary Brown of TRS.  Thanks so 
much Gary, for the wonderful top-quality rewinding of the transformer!

I replaced the QSK board with a spare (socketed) one that the previous owner had included 
with the amplifier. He also had some new 4011 chips in there so I put new ones in for U1 and 
U2. The 5 transistors all tested good. Bingo - no more "TX" light on all the time.

I removed the FAN modification the previous owner had done and now the fan works. 
Honestly, the sound of the fan is NOT objectionable at all and I am happy to let it run and 
keep my tubes cool  all the time! I just removed two header plugs that inserted a  
potentiometer and a series temperature sensor that had been mounted near the tubes. I cut 
off the wires and put heat shrink tubing over the ends of them.
 
Now I have the extra pot in the back, buit I don't have to look at it so it's no big deal, and I 
have a great working 422 again!

Now all we need is some propagation that will send decent signals my way! I can tell we are 
heading toward the summer doldrums...

THANK YOU to everyone on this group whose advice and experience helped me to pull of 
this repair.

73 de AF4K, Bry


On 16 Mar 2014 at 21:55, Bob McGraw - K4TAX wrote:

> Without proper cooling the current through the tube filament pins will 
> likely melt the solder from the pins thus tube failure is imminent. Take the 
> pot out of the fan circuit as it can inhibit the fan starting and thus one 
> can expect a cooling failure.
> 
> 73
> Bob, K4TAX
> 
> 
> ----- Original Message ----- 
> From: "Brian Carling" <bcarling at cfl.rr.com>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Sunday, March 16, 2014 9:36 PM
> Subject: Re: [TenTec] Centurion Amp QSK Board
> 
> 
> > Yes and the good news is my Centurion is up and running after I replaced 
> > the two chips on the QSK board today.
> > However the fan still won't run so I need to fix that before using it any 
> > more.
> >
> > I always used proper tuning but perhaps the fan failed and caused this. 
> > Either that or something came loose during the repair. Mine has had a pot 
> > added to the fan circuit.
> >
> > Best regards - Bry Carling
> >
> >
> >
> >> On Mar 16, 2014, at 9:54 PM, "Bob McGraw - K4TAX" <RMcGraw at Blomand.net> 
> >> wrote:
> >>
> >> I, on the other hand, purchased my Centurion new in 1991.  Sold it last 
> >> year still with the original transformer, QSK board and tubes and making 
> >> 1200 to 1500 watts out.  No failures and it acquired several thousand 
> >> hours of operation.  I deem that proper tuning is the key to success and 
> >> longevity.
> >>
> >> While the AL-82 is a good, no very good amp but it does not offer the 
> >> slick and full QSK of the Centurion, unless one adds the QSK-5 kit.  I 
> >> considered the QSK-5 kit with my new AL-80B but decided against it.  I 
> >> elected to go another route.
> >>
> >> 73
> >> Bob, K4TAX
> >>
> >>
> >>
> >>
> >> ----- Original Message ----- From: <bcarling at cfl.rr.com>
> >> To: <tentec at contesting.com>
> >> Sent: Sunday, March 16, 2014 8:59 AM
> >> Subject: Re: [TenTec] Centurion Amp QSK Board
> >>
> >>
> >>> Thanks Don - I will call them tomorrow and buy the kit. Or find those 5 
> >>> parts on the web.
> >>>
> >>> This QSK board was already replaced once by the previous owner.
> >>> It seems to be the other one of two very weak links in the design of 
> >>> Tentec amplifiers.
> >>> Power transformer and QSK board..
> >>>
> >>> I love it when my 422 works right,  but if I had it to do over I would 
> >>> have bought an AL-82
> >>> or something similar.
> >>>
> >>> 73 - Bry
> >>>
> >>>> On 15 Mar 2014 at 22:09, Donald, K6RV wrote:
> >>>>
> >>>> Bry,
> > _______________________________________________
> > TenTec mailing list
> > TenTec at contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> > 
> 
> 
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