[TenTec] TenTec Centurion problem

[Duane A Calvin]

Just to show the other side - I owned my Centurion for three years, and
it saw a lot of use in QSK CW.  I never had a problem with any of the
keying circuitry or relays - it was rock-solid.  I hope my Alpha 99 does
as well.

        73,  Duane


On Mon, 26 Nov 2001 07:53:19 -0600 "Jim Cox" <jcox@digitalexp.com>
writes:
> 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
> > >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
> 
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
> 


Duane Calvin, AC5AA
Austin, Texas