[TenTec] Centurion Amp QSK Board

Donald, K6RV K6RV at earthlink.net
Thu Feb 6 13:09:26 EST 2014

It appears after reviewing my QSK board problem and the blown fuses in 
my Centurion, that I mis-wrote what happened.

I indeed had the same symptoms you had:  Blown fuses for no apparent 
reason.  In my case the QSK board was blown, but in talking to Ten-Tec 
service yesterday, they said the sequence happened like this:  There was 
a high voltage short from one of the 3-500Z tube plates to the top of 
the cabinet, causing the fuses to blow.  Guess when I had replaced the 
tubes, one of the plate straps was too close to the top of the case and 
arced over.   The blowing of the fuses created a surge, or a spike, 
which blew out the QSK board.  The QSK board is very sensitive to the 
fuses being blown, for whatever reason.

You may find, that the QSK board is blown in addition to the transformer 
being shorted.  The symptom will be that the standby/operate switch does 
not work as it should, and the transmit light will be constantly on.  If 
that is the case, then you can get the "kit" to rebuild the QSK board, 
or send the board to Ten-Tec for them to re-build, or have them send you 
a new QSK board  (Cost = $97), and/or the "kit" to rebuild your old 
board and have as a spare. That is what I did. The Kit consists of 2 
IC's and 5 Transistors, and cost about $20, as I remember.

I know you are concerned about putting so much money into the amp., but, 
in my view, it is both necessary, and worth it, especially since you 
already will have the big bucks invested in the re-wound transformer.

Again, Bry, good luck !

73, Donald K6RV

Message: 14 Date: Tue, 4 Feb 2014 06:18:44 -0800 From: Bry Carling 
<bcarling at cfl.rr.com>

To: Discussion of Ten-Tec Equipment <tentec at contesting.com> Cc: 
"tentec at contesting.com" <tentec at contesting.com> Subject: Re: [TenTec] 
Centurion Amp. Problem Message-ID: 
<42FCECBC-F96D-40EC-ACBB-A21415410F44 at cfl.rr.com> Content-Type: 
text/plain; charset=us-ascii

Thank you so much. They never brought up that possibility during my 
calls to Tentec while troubleshooting. However the previous owner did 
mention to me that the QSK board had already been replaced. This amp is 
trying my patience. It's not just the money but the time. If I end up 
replacing the QSK board too then I will have enough into it to have 
bought a nicer amplifier. It's disappointing to think a QSK board could 
cause main fuses to blow. I will try to learn how to troubleshoot that 
section while my transformer is away being rewound. Thank you so much 
for the insight about the QSK circuit. Bry AF4K

  Best regards - Bry Carling

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