TenTec
[Top] [All Lists]

Centaur 411 Amp

To: <tentec@contesting.com>
Subject: Centaur 411 Amp
From: n4xy@avana.net (Ed Tanton)
Date: Sun, 22 Dec 1996 17:56:10 -0500
I'm sorry Chuck... I think concern over a 12 hour drift of well under 100
hz for voice communications is absurd.  Flame away.

At 09:29 AM 12/22/96 -0600, Chuck (Jack) Hawley wrote:
>Paul, Wv3j wrote:
>> 
>> After reading the Article in CQ and observations from other users (and as
>> one who has been well satisfied with Ten Tec's gear and service) I ordered
>> one of the demo Centaur 411 amps.  I am now about half way through the
>> month's evlauation period.  The amp was clean inside and humidity was low.
>> I warmed it up several minuits before beginninig to check it out into my kW
>> dummy load and through my 238 tunner to an 80 Mtr loop antenna. I had
>> several problems right from the start:
>> 
>>         A loud THUNK on power up.
>
>So not we know that it doesn't have a step start....not unusual though
>for this price class but too bad anyway. I wonder if the (cheap), in
>series with the line current, thermister type of current limiting would
>be a good idea for these inexpensive power supplies (Astrons), amps and
>things?
> 
>>         Frequent arcing of the plate tuning capacitor.
>
>That's what Doug DeMaw said in the CQ "review" but I think he should
>have gone on to say "don't buy it". I pretty much decided to drop CQ
>magazine based on the superficial reviews that McCoy and DeMaw put out.
>They are both nice guys it seems and pretty smart cookies but if they
>won't be knowlegeable or straight about what they are looking at
>(subconsciously or otherwise) then who needs to pay 'em to do product
>reviews for the rest of us.
>
>>         Low output indicated by the 411's and 238's wattmeters as follows:
>> 
>>                 f       Load    Tune    Ant     P (411)   P (238)  Notes
>> 
>>                 1850    10      7       loop    475       600     80mA grid
>> 
>>                 3500    8.5     3.5     dummy   450       500
>> 
>>                 3670    5       3       loop    450       500     @1.6 kv
>> 
>>                 4000    1       2.5     loop    425       <500
>> 
>>                 7.125   9       1.5     loop    475       500    1.6 kv,
>> 100mAg, 5000mAp
>> 
>>                 14.200  7       1       dummy   400       450    same w/
loop
>> 
>>                 21.200  7.8     1       dummy   250       150
>> 
>> Post conversion 28.100  7       1       dummy   50         40   100w in,
>> 120mAg, 400mAp
>
>I'm not qualified to comment on the poor performance but I'm sorry to
>learn about these additional questions about the amp. I guess I would be
>wondering about the tubes also.
> 
>> (The old SB 200 loaded all these frequencies easily with no arcing and with
>> full power indicated by the 238 (except 160 meters, which it was not
>> designed to do)).  I thought maybe the 15 meter low pass filter might be
the
>> problem particularly on 15 mtrs, so I got the 10 mtr conversion from Ten
Tec
>> and installed it.  Unfortunately things remain as tabulated above,
difficult
>> to get a dip on 20 mtrs and above, with poorer  output as frequency is
raised.
>> 
>> Did I get an amp with bad tubes for my 5% demo savings or did I get a bad
>> amp?  If the tubes are bad did the former operator of this demo amp maybe
>> ruin them and maybe also arc the cap plates so much that they are now too
>> close at melted edges?  I'd have thought a demo would have been gone over a
>> time or two more than a new one.  I was prepared for (and not alarmed by)
>> the small scratches and paint chips, but not for sub-standard performance.
>
>I woulda been disturbed by the scratches and chips. Is there a simple
>cover that can be replaced for 10 or 15 bucks that took most of the
>scratches? I always figured that I would be safe buying a TT because
>they could supply me with a new cover for most of their stuff.
> 
>> I'm sure Ten Tec will make good on this as they have always done, but it is
>> the beginning of the weekend, and Christmas shipping nightmare to boot.
>> I'll call them Monday, but meantime I'd welcome comments from any of you as
>> to the probable nature of these problems.
>> 
>> Thanks and Christmas greetings too all.
>> 
>> 73,
>> 
>> Paul Helbert - Wv3j
>
>Good luck. It's really difficult to deal with these well meaning, nice
>people when they just don't have the same technical rules and standards
>that you have. Although I'm sure that your reduced output on the higher
>bands is below their standards, I am reminded of the guys I know who
>tried in vain to like the Omni 5's and 6's that drifted or jumped 30,
>50, or 80 hertz from night to night on 75 Meter phone. It's not that
>important.....but darn it...it's frustrating when you spend a couple of
>hours to get it really close and then it's off again the next night. The
>factory thinks you're nuts to be nit picking like this....so eventually
>these guys drifted back to rice boxes that always end up at the same +/-
>3 hertz every night. Now we can do that in this country and it shouldn't
>matter why we want it.....the rest of the world seems to think it's
>important enough to do it and is willing to sell us expensive tcxo's.
>Now I know I'm going to hear a bunch of stuff about phase noise and
>crystal controlled oscillators....can't we do it with more stability?
>...even though it doesn't matter? I guess not....not with voltage
>controlled capacitors pulling the crystals and microprocessors
>correcting the master oscillator at least.
>
>I really want to say some more about my brain damaged TT auto tuner but
>it's discontinued and nobody seems to know anything about it, so I won't
>mention it.
>
>Paul, is there room for a bigger tune cap in there? Just wondering.
>
>73, Chuck, KE9UW
>
>
>--
>FAQ on WWW:               http://www.contesting.com/tentecfaq.html
>Submissions:              tentec@contesting.com
>Administrative requests:  tentec-REQUEST@contesting.com
>Problems:                 w9tw@contesting.com
>Sponsored by:             Akorn Access, Inc & KM9P
>
>
72/73 

Ed Tanton N4XY      EMAIL: n4xy@avana.net      TEL: (770)579-3933 V/MBX/FAX
189 Pioneer Trail, Marietta, GA  30068-3466

QRP-ARCI#7663    G-QRP#6779    OK-QRP#172    QRP-L#758    AdvRC#140
NORCAL#1779       NCDXF              SEDXC

Life Member:  ARRL     AMSAT     IDRA     INDEXA     QCWA     URL: Coming Soon

"Think you can, think you can't: either way you're right!"  Henry Ford

--
FAQ on WWW:               http://www.contesting.com/tentecfaq.html
Submissions:              tentec@contesting.com
Administrative requests:  tentec-REQUEST@contesting.com
Problems:                 w9tw@contesting.com
Sponsored by:             Akorn Access, Inc & KM9P

<Prev in Thread] Current Thread [Next in Thread>