[TenTec] Model 411 amp (aka Centaur)

Thu Jan 28 09:45:00 EST 2016

Good morning Joe,

Yes, my AMP does make a "thunk" when turned on,  but, for example,  I have been using it for an hour.  Then I turned it off.  Now, 15 minutes later, I turn it on and it does not "Thunk".

I found that this AMP was built well, and the only issues for over 20 years have been the tubes, and of of the toggle switches  (IP/EP).  The change to 10 meters was a snap.

Yes, it could have a quieter fan, but it is a good AMP and makes an S-unit difference.

Good luck with the tubes.  BTW  I have used it with only two tubes, while waiting for a new set.  

Kris

Kris KM2KM 
MERSCHROD
123 Warren Road
Ithaca, NY 14850

---- Joe Papworth via TenTec <tentec at contesting.com> wrote: 

=============
Hi Kris,
Thanks for the info.
It sounds like that store proprietor had gone a few rounds with some rigs. Hi hi
I'll try the tubes by adding one at a time tomorrow.
Say, does your Centaur make a loud in-rush clunk when you fire it up?
And where did you buy your matched set?

Later, Joe, K8MP

Sent from AOL Mobile Mail

-----Original Message-----
From: km2km <km2km at twc.com>
To: Discussion of Ten-Tec Equipment <tentec at contesting.com>
Sent: Tue, Jan 26, 2016 06:28 PM
Subject: Re: [TenTec] Model 411 amp (aka Centaur)

I'm late chiming in.   My problem with the fuses has always been a shorted tube. You are on the right track.   Test one fuse at a time, or start with one, add another, then the third.  BTW a matched set is better than an unmatched set HOWEVER,  I had three misc tubes gathered over the years and put them in and do pretty well with them.  I did that while waiting for a new matched set.  Now the matched set is on the shelf waiting their turn!!!

The guy at the local electronics store said to me one day when I bought a dozen fuses, "You do know that if you don't fix it then it will still blow fuses!" 

good luck,

Kris

Kris KM2KM 
MERSCHROD
123 Warren Road
Ithaca, NY 14850

---- Joe Papworth via TenTec <<a href='mailto:tentec at contesting.com'>tentec at contesting.com> wrote: 

=============
It has stayed on with the tubes removed for a while.?
I'm examining/ohming the tubes now.

-----Original Message-----
From: Carl Moreschi <<a href='mailto:n4py3 at earthlink.net'>n4py3 at earthlink.net>
To: wb5jnc <<a href='mailto:wb5jnc at centurytel.net'>wb5jnc at centurytel.net>; Discussion of Ten-Tec Equipment <<a href='mailto:tentec at contesting.com'>tentec at contesting.com>
Sent: Tue, Jan 26, 2016 3:03 pm
Subject: Re: [TenTec] Model 411 amp (aka Centaur)

Don't overlook the possibility on an intermittent short in one of the 811's. 

Carl Moreschi N4PY 
58 Hogwood Rd 
Louisburg, NC 27549 
<a href="http: www.n4py.com" target="_blank">www.n4py.com 

On 1/26/2016 2:54 PM, Al Gulseth wrote: 
> Joe, 
> 
> Just an ohms check may not be enough. You may be dealing with an intermittent 
> breakdown under high voltage. A "hi-pot" (high potential) test with an 
> insulation tester etc. would be the only way to know for sure. A winding 
> layer to adjacent layer partial short in the HV side could also account for 
> your symptoms, and might not be obvious because the winding resistance could 
> show right at the low edge of the manufacturer's spec. (I went through that 
> scenario years ago with a HV filter choke in a small AM BC transmitter.) 
> 
> 73 es GL, Al 
> 
> On Tue January 26 2016 11:28:03 am Joe Papworth via TenTec wrote: 
>>     Thanks Andy. Was it the HV secondary that shorted? 
>> 
>> 
>>    I isolated the HV secondary from the HV board and it reads open to the 
>> frame and chassis. (Reads about 45 ohms when connected to the board) 
>> 
>> 
>>    Thanks, Joe, K8MP 
>> 
>> 
>>   -----Original Message----- 
>>   From: P C Andy Anderson<<a href='mailto:xtraham58 at hotmail.com'>xtraham58 at hotmail.com> 
>>   To: Discussion of Ten-Tec Equipment<<a href='mailto:tentec at contesting.com'>tentec at contesting.com> 
>>   Sent: Tue, Jan 26, 2016 11:52 am 
>>   Subject: Re: [TenTec] Model 411 amp (aka Centaur) 
>> 
>> 
>> 
>> 
>>   Joe, I had a similar problem with my Centurion AMP.  It eventually failed 
>>   completely. The secondary of the power transformer shorted to the frame. I 
>> had the Xformer rewound at TRS.  BTW this transformer problem is a known. 
>> 
>>   73' Andy, W3LI 
>> 
>>   ________________________________________ 
>> 
>> 
>>   Tuesday noontime, Joe: 
>> 
>>   I have a Centaur..............keep it covered when not in use. 
>> 
>>   My Elmer told me to always keep it covered..................dust is the 
>>   problem. 
>> 
>>   Even when covered, open it up every two-three years and do a internal 
>>   cleaning. 
>> 
>>   N1MHC/alsirois 
>>   ============= 
>> 
>> 
>> 
>>   Gents, 
>> 
>> 
>>   Have any of you gone a few rounds with a Centaur amp? 
>>   I have a one that blows fuses very intermittently. It vaporizes them both, 
>>   simultaneously, so it's apparently a dead-short somewhere. This happens 
>> even in stand-by. (i.e. No key-down) 
>> 
>> 
>>   Before I tear into it, anyone have any ideas of common failures in these 
>>   amps? 
>> 
>> 
>>   Later, Joe, K8MP 
>> 
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