[TenTec] TenTec Centurion problem

[Robert & Linda McGraw K4TAX]

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
>