I had a Centurion for about a year or so and had problems with the QSK board
twice during that time. Easy to repair but I lost confidence in the
reliability of the amp. Jim K4JAF
----- Original Message -----
From: Robert & Linda McGraw K4TAX <RMcGraw@Blomand.Net>
To: Dave Bowker <dbowker@mail.sjv.net>; <tentec@contesting.com>
Sent: Sunday, November 25, 2001 9:52 PM
Subject: Re: [TenTec] TenTec Centurion problem
> Never had any problem with my Centruion, it's relays or switching
circuits.
> Guess I been lucky.
>
> Or is it that I make sure of the load and its SWR before I switch on the
> amp. A 3:1 SWR, especially if it's a low Z, will certainly do damage.
>
> 73
> Bob K4TAX
>
>
> ----- Original Message -----
> From: "Dave Bowker" <dbowker@mail.sjv.net>
> To: <tentec@contesting.com>
> Sent: Saturday, November 24, 2001 7:04 AM
> Subject: RE: [TenTec] TenTec Centurion problem
>
>
> > This is a commom problem with TT QSK amps.
> >
> > You can replace the Kilovac K41C234 relay with a RJ1A relay. The RJ1A is
> > available on surplus market for as little as $35. I can supply .JPG
> photos
> > of the relay replacement in a Titan Amp, which may assist you with your
> > Centurian. Replacement will require reconfiguration of the relay driver
> > board for 26 volt operation by removal of a resistor.
> >
> > Alternatively, you can affect a short term repair of the K41C234 relay
by
> > removing it from the amp., wiring the coil in series with the NC
contact,
> > and applying 12 VDC to the series combination for a short period of
time.
> > This will cause the relay to oscillate and pass current through the
'RECV'
> > contacts (NC) and cleanse them. This is only a temporary cure...see the
> > explanation below. The following is an explanation, which I have posted
> to
> > this reflector several times.
> >
> > Relay Contact Failures:
> >
> > Relay manufactures design the contacts of their relays for specific
> > applications. Relays generally carry an application rating such as
'Make
> &
> > Break Load Switching', 'No Load Switching', 'Make Only Load
Switching',
> > etc. The selection of the proper relay for a specific application is
> > crucial to the life of the relay and it's performance in the circuit.
> > Relays rated as 'Make and Break Load Switching' depend upon current flow
> > through BOTH the normally closed AND normally open contacts in order to
> > maintain a specified minimum contact resistance over the specified life
of
> > the relay. Use of such a rated relay in a circuit where no current
flows
> > through either the NC or NO contacts can cause contact resistance to
> > increase over time and the relay will eventually fail to provide circuit
> > continuity through the contacts. This is sometimes misinterpreted to be
a
> > sticking relay armature problem.
> >
> > Use of such a relay in an QSK amp where "hot switching" is prevented by
> > circuit design but also no current flows through the NC contacts (on
> > receive) will eventually cause these symptoms to occur, usually
identified
> > as "no signal or a greatly attenuated signal on receive". Rapping the
> relay
> > may cause the symptom to disappear (for awhile) and is often interpreted
> as
> > a sticking solenoid versus a contaminated NC contact. A better choice
for
> > such an application would be a relay whose contacts are rated as 'No
Load
> > Switching'.
> >
> > The specifications on the K41C234 and RJ1A relays may be obtained from
the
> > Kilovac www site at: http://www.hv-relays.com/home.htm. Pay attention
to
> > the ratings for the K41C234, which is rated as 'Make & Break Load
> Switching'
> > while the ratings for the RJ1A are for 'No Load Switching', a far better
> > choice for the application in TT amps. since no current flows thru the
NC
> > contacts during receive.
> >
> > 73, Dave, K1FK
> > Fort Kent, ME
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
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