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Re: [Amps] Centurion Problems - Arcing on 10, 15 and 20 mtrs

To: <>, "Dan Atchison" <>, <>, "Jim W7RY" <>
Subject: Re: [Amps] Centurion Problems - Arcing on 10, 15 and 20 mtrs
From: "Carl" <>
Date: Tue, 21 Jun 2011 08:52:38 -0400
List-post: <">>
A parasitic suppressor could be fried if the arcing is in the Tune cap or 


----- Original Message ----- 
From: <>
To: "Dan Atchison" <>; <>; "Jim W7RY" 
Sent: Monday, June 20, 2011 10:57 PM
Subject: Re: [Amps] Centurion Problems - Arcing on 10, 15 and 20 mtrs

> Dan,
> I can sympathize with you. I have a Centurion which I purchased used in 
> very
> good condition. Had it for a few years and poof went the HV xfmr while the
> unit was in standby. The amp was approximately 16 years old when the xfmr
> primary opened as you described.  $550 later, I had a new TT replacement
> xfmr and we were back in business (but a bear to remove and replace). Now, 
> 3
> years later, the amp is arcing on 20 mtrs into a dummy load. Have not
> checked it out yet, but put my trusty 40 year old SB-220 back on line 
> (with
> original caps, etc) and will get around to the Centurion when time 
> permits.
> Would be curious to know if anyone else has seen an arcing problem which
> immediately causes the Power Output to drop to zero.  The problem does not
> seem to exist on 40/75 mtrs but is prevalent on 10, 15 and 20 into a Bird
> dummy load.
> 73 and good luck,
> Dave
> ----- Original Message ----- 
> From: "Dan Atchison" <>
> To: <>; "Jim W7RY" <>
> Sent: Sunday, June 19, 2011 8:13 PM
> Subject: [Amps] Centurion
>> Well, interesting repair.  Yes, the problem was a leaky Q1 on the
>> display board.  Replaced with a non-descript  2N3904 since I didn't have
>> the 2N4124 that was bad.  Schematic called for a different transistor
>> altogether.
>> Delving into the circuit also revealed why I had no PTT.  Seems if the
>> amp detects RF output prior to PTT, then the PTT circuit is disabled.  I
>> had no RF output, but the leaky transistor had the same effect as
>> rectified RF allowing voltage where it was not wanted!
>> Also found out the step-start circuit is fried.  Read that as the power
>> resistor is fried.  The board it's on is behind the HV transformer so I
>> may just leave it alone.
>> I know many people have Centurions.  This one is a 422B, the black (and
>> current) faced amp.  I've had it almost eight years now and it's been a
>> problem child.   Early on in its life I lost two HV transformers.
>> Tentec had a problem with these and never, NEVER admitted as such.  One
>> was replaced under warranty, the next one lasted seven months.  Both
>> failed with shorted primaries.  After the second failed, I bit the
>> bullet and bought a Peter Dahl and never looked back.  I had Dahl
>> slightly up the secondary voltage on this one.
>> This is about the sixth repair on the unit, by far and away my least
>> reliable piece of equipment.  Even the schematics are wrong -- and I
>> bought the amp after it had been on the market already for 15 years or
>> so.  Even the board screened nomenclature was incorrect on a few boards
>> that I noticed while troubleshooting.   I may never buy another piece of
>> Tentec gear again.
>> _______________________________________________
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