Re: [TenTec] Ten-Tec 411 Centaur Amp Problem

["Dr. Gerald N. Johnson" <geraldj@weather.net>]

There is no input bandswitch. There are no bandswitching relays. There 
is a low pass filter and a resistor. The stock lowpass in the manual 
cuts off to prevent use at 11 and 10 meters. The 10 meter option changes 
that low pass filter, I gather, but the details are not in the owner's 
manual (per FCC regulations). There is nothing overtly frequency 
sensitive unless there are bad solder connections or board grounding for 
that filter.
I made my first post (like you) without consulting the manual. A pdf of 
that manual now resides on this computer. The tuner test is legit. Ad 
worthwhile test.
Soldering 12 gauge wire and 25 watt resistors might work better with a 
100 watt iron, a 50 watt iron may cool off so fast it gets soldered to 
those parts.
73, Jerry, K0CQ

On 5/27/2010 6:12 PM, Rick - NJ0IP / DJ0IP wrote:
> Kris,
>
> OK, I think we are honing in on the source of your problem.
> My hunch is that something has changed in the input circuit of you amp.
> Not a big problem.  The parts used there cost peanuts.
>
> As a next step, please take some kind of matchbox (anything) and place it
> between you transceiver and your linear.
> The SWR is now 3:1.  Use the tuner to drop it to 1.5:1 or less.
> Check the power out of your linear now.
> My hunch is that it will be 500w....which should be ok.
>
> Assuming that is what happens, we have something gone south in the input
> circuit of your amp.
>
> - take a small soldering iron (abt 50w) and carefully resolder ALL
> connections in the 40m section of the input circuit.  Add additional solder
> as necessary.  Be sure the solder flows on all joints.
>
> If it still does not work right, then probably one of the 3 components has
> changed values (I'm speculating here; I'm assuming you have a coil and 2
> capacitors).  For sure something is amis in this circuit.
>
> I forgot something.
> The band switching is probably done with relays.
> Resolder all of the connections to the 2x 40m relays too.
>
> My hunch is that simple resoldering everything in this area will fix your
> problem.
>
> Remember, all of this is based on the assumption that using a matchbox to
> adjust the SWR between rig and amp, you are able to get full power out.
>
> Good luck.  I'm standing by for your feedback.
>
> 73
> Rick
>
> -----Original Message-----
> From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> On Behalf Of Kris Merschrod
> Sent: Thursday, May 27, 2010 1:15 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Ten-Tec 411 Centaur Amp Problem
>
> Rick,  Thank you - I'LL ANSWER THE QUESTIONS IN CAPS.
>
> Kris KM2KM
>
> > Need more info:
> >
> > 1.  Have you tried it on a dummy load?  If so, was it OK, or also 375w on
> > 40m?
> YES, SAME PROBLEM
> > 2.  Did this suddenly occur, or has it always been this way?  Or is it new
> > and being tried first time?
> IT HAS BEEN THIS WAY FOR A LONG TIME.  ABOUT FOUR MONTHS AGO I REPLACED THE
> TUBES WITH A MATCHED SET - SAME PROBLEM
>
> > 3.  What transceiver are you driving it with?
> TEN TEC DELTA II
> > 4.  What is the SWR between the transceiver and the Linear on each of
> > these
> > bands?
> BINGO   3:1  ON 40 METERS NO SWR ON THE OTHERS  WHEN IN LINE WITH THE AMP ON
>
> AND TUNED UP
> > 5.  What is the output of your transceiver on each of these bands?  (If
> > it's
> > down on 40, then the issue is not the linear).
> OK, IT IS CUTTING BACK B/C OF THE SWR
> > 6.  Assuming this has suddenly occurred, and it was previously working
> > correctly, carefully examine the settings of the Tune and Load controls.
> > Have they changed significantly from their settings when it was working
> > properly?
> MOOT QUESTION NOW
> > When we know the answers to these questions, maybe something will give us
> > further clues.
> >
> > 73
> > Rick
> >
> > -----Original Message-----
> > From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> > On Behalf Of Kris Merschrod
> > Sent: Thursday, May 27, 2010 12:55 PM
> > To: Discussion of Ten-Tec Equipment
> > Subject: [TenTec] Ten-Tec 411 Centaur Amp Problem
> >
> > Wow, now that Joe (K0BX)  has managed to slid in edgewise by taking
> > advantage of the great TT QSK while the discussion group was in CW
> > mode!!!!
> >
> > Here is the issue that I have.  On 40 meters, into a resonant 40 meter
> > loop,
> >
> > the Centaur will only put out 375 atts.
> > On 80 meters and 20 meters it puts out the appropriate power  (500+ Watts)
> > while using a tuner into an 80 meter dipole.  On 40 Meters, through the
> > tuner, into an 80 meter diople it will only put out the same 375 watts.
> >
> > Where can the problem be?
> >
> > Kris KM2KM
> > Merschrod
> > 123 Warren Road
> > Ithaca, NY 14850
> > www.merschrod.net/KA2OIG.htm
> >
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