[TenTec] Ten-Tec 411 Centaur Amp Problem

Thu May 27 16:21:55 PDT 2010

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 at contesting.com [mailto:tentec-bounces at 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 at contesting.com [mailto:tentec-bounces at 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
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec at contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec at contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>