[TenTec] Model 411 amp (aka Centaur)

george fritkin georgefritkin at yahoo.com
Thu Feb 4 18:32:47 EST 2016 

I did that to my centaur. Unlike the Ameritrons the TenTec power supply will crank out more pwr with 572

George,w6GF


Sent from my iPhone

> On Feb 4, 2016, at 2:55 PM, Joe Papworth via TenTec <tentec at contesting.com> wrote:
> 
> Yep, finding good tubes has been very frustrating. I just sent the new 811A's with the prematurely sagged plates back to DX Engineering. 
> I have two, working, 40-plus-year-old Cetron 572B's that I pulled out of my SB-200 some years ago. My next (and probably last) try is those two tubes with a new Cinese 572B. It's an iffy proposition at best, but I'm tired of throwing money at the amp.
> 
> 
> Sent from AOL Mobile Mail
> 
> 
> -----Original Message-----
> From: rick at dj0ip.de <Rick at DJ0IP.de>
> To: 'Discussion of Ten-Tec Equipment' <tentec at contesting.com>
> Sent: Thu, Feb 4, 2016 02:03 PM
> Subject: Re: [TenTec] Model 411 amp (aka Centaur)
> 
> 
> Al,
> 
> Unfortunately 2016 is not 1999.
> It's tough to find good tubes anymore.
> 
> A few years ago, RF-Parts stopped the sales of 572B entirely until they
> could work with their Chinese supplier and get the quality up to snuff.
> They refused to sell an inferior product.
> 
> On their web site, RF-Parts writes "The Taylor Select 811A is the best
> quality tube in current production." Obviously they mean best quality 811A.
> The cost of a matched set of 3 is currently $95.85.
> 
> 572B's are scarce.  They are available in very limited quantities with a
> matched set of 3 costing $239.85.  More than twice the price of 811A.
> 
> It seems there is a waiting list.
> See:  <a href="https://www.rfparts.com/572b-tubes" target="_blank">https://www.rfparts.com/572b-tubes</a> 
> 
> 73 - Rick, DJ0IP
> (Nr. Frankfurt, Germany)
> 
> 
> 
> -----Original Message-----
> From: TenTec [<a href="mailto:tentec-bounces at contesting.com?">mailto:tentec-bounces at contesting.com</a>] On Behalf Of Al Sirois
> Sent: Thursday, February 04, 2016 6:53 PM
> To: <a href="mailto:km2km at twc.com">km2km at twc.com</a>; <a href="mailto:tentec at contesting.com">tentec at contesting.com</a>
> Cc: Ron Sirois; <a href="mailto:k8mp at aol.com">k8mp at aol.com</a>
> Subject: Re: [TenTec] Model 411 amp (aka Centaur)
> 
> TUBES..........My T-T Manual says to use 811-A, not 572-B.....>
> 
> I bought matched tubes from RF Parts in 1999 and they are still in the amp
> 
> and working fine. I got 450 W out of them this morning on 80 meters.
> 
> I do have spare 572-B's, but they are for my back-up amp a FL-2100-B.
> 
> I've never swopped the tubes between the two amps..... I probably don't want
> to.
> 
> Good Luck with you guys in this discussion group.
> 
> <a href="mailto:N1MHC at arrl.net">N1MHC at arrl.net</a>
> Al Sirois
> East Boothbay, ME 04544-0002
> ==========================
> 
> -----Original Message-----
> From: Joe Papworth via TenTec
> Sent: Thursday, January 28, 2016 9:54 AM
> To: <a href="mailto:km2km at twc.com">km2km at twc.com</a> ; <a href="mailto:tentec at contesting.com">tentec at contesting.com</a>
> Cc: <a href="mailto:k8mp at aol.com">k8mp at aol.com</a>
> Subject: Re: [TenTec] Model 411 amp (aka Centaur)
> 
> Thanks Kris,
> If I was desperate, I'd run it on two tubes.?
> BTW- I haven't bit the bullet on a new tubes yet cuz from what I read on the
> net, the ones on the market now just plain suck.
> 
> 
> Seeeeeeeeeeeeya, Joe
> 
> 
> -----Original Message-----
> From: km2km <<a href="mailto:km2km at twc.com">km2km at twc.com</a>>
> To: Discussion of Ten-Tec Equipment <<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>>
> Cc: k8mp <<a href="mailto:k8mp at aol.com">k8mp at aol.com</a>>
> Sent: Thu, Jan 28, 2016 9:45 am
> Subject: Re: [TenTec] Model 411 amp (aka Centaur)
> 
> 
> 
> 
> 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 <<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>> 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 <<a href="mailto:km2km at twc.com">km2km at twc.com</a>>
> To: Discussion of Ten-Tec Equipment <<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>>
> 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='<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>?'<a href="mailto:tentec at contesting.com" >tentec at contest?'="">mailto:tentec at contesting.com'>tentec at contest</a>
> ing.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='<a href="mailto:n4py3 at earthlink.net">n4py3 at earthlink.net</a>?'<a href="mailto:n4py3 at earthlink.net" >n4py3 at earthlink.ne?'="">mailto:n4py3 at earthlink.net'>n4py3 at earthlink.ne</a>
> t>
> To: wb5jnc <<a 
> href='<a href="mailto:wb5jnc at centurytel.net">wb5jnc at centurytel.net</a>?'<a href="mailto:wb5jnc at centurytel.net" >wb5jnc at century?'="">mailto:wb5jnc at centurytel.net'>wb5jnc at century</a>
> tel.net>;
> Discussion of Ten-Tec Equipment <<a 
> href='<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>?'<a href="mailto:tentec at contesting.com" >tentec at contest?'="">mailto:tentec at contesting.com'>tentec at contest</a>
> ing.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: <a href="http://www.n4py.com" target="_blank">www.n4py.com</a>" target="_blank"><a href="http://www.n4py.com" target="_blank">www.n4py.com</a>
> 
> 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='<a href="mailto:xtraham58 at hotmail.com">xtraham58 at hotmail.com</a>?'<a href="mailto:xtraham58 at hotmail.com" >xtraham58 at hotm?'="">mailto:xtraham58 at hotmail.com'>xtraham58 at hotm</a>
> ail.com>
> 
> >> To: Discussion of Ten-Tec Equipment<<a 
> href='<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>?'<a href="mailto:tentec at contesting.com" >tentec at contest?'="">mailto:tentec at contesting.com'>tentec at contest</a>
> ing.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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