[TenTec] 422 Centurion blowing fuses...

[Bob McGraw - K4TAX]

Sorry to learn of the bad news.

There are companies around that can rewind/rebuild that transformer. 
Certainly worth checking into as opposed to engineering some other 
transformer in its place.
Per chance have you had a lightning strike lately?  That will do it.

73
Bob, K4TAX



----- Original Message ----- 
From: "Bry Carling" <bcarling at cfl.rr.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, January 30, 2014 9:54 PM
Subject: Re: [TenTec] 422 Centurion blowing fuses...


> Thanks Bob, but the power transformer is shot.
>
> It spontaneously died for no apprent reason. Tubes are not shorted, and 
> the rectoifoers amd
> cap are intact.
> One of the two primary windings has shorted out completely. The other is 
> OK.
>
> Anyone have a hypersil transformer they would like to sell?
>
> Brian, AF4K
>
> On 30 Jan 2014 at 17:21, Bob McGraw - K4TAX wrote:
>
>> When the power switch is ON there is the HV also applied.  Thus I
>> wouldn't
>> expect shorted tubes or any HV component.  Likely the bias diode
>> shorted
>> thus when switched to Operate the tubes fully conduct and take out
>> the fuse.
>> Watch for Plate current to peg.
>>
>> With amp ON and the Operate switch in Standby, you should be able to
>> see the
>> HV on the meter.  The Operate switch basically changes the control
>> mode,
>> thus the internal T/R switching is activated.
>>
>> 73
>> Bob, K4TAX
>>
>>
>> ----- Original Message ----- 
>> From: "Bry Carling" <bcarling at cfl.rr.com>
>> To: <tentec at contesting.com>
>> Sent: Thursday, January 30, 2014 2:30 PM
>> Subject: [TenTec] 422 Centurion blowing fuses...
>>
>>
>> >I have a Tentec 422 Centurion that is blowing the main 20 Amp
>> fuses...
>> >
>> > Looking for insights to this amp failure.  It started
>> spontaneously.
>> > I can turn on the main power OK and the filaments light up on
>> the
>> > 3-500Zs.  The 12 volt power supply is OK because the pilot lights
>> come on.
>> > However when I flip the standby - operate switch to the Operate
>> positionm
>> > the fuse or fuses will blow.  I replaced them with good 250V 20A
>> cuses.
>> >
>> > I checked the plate transformer windings and everything seems
>> normal for
>> > all three windings. Nothing is shorted. The safety ground for the
>> > cover-open condition is not
>> > across the HV plate supply. I checked that nothing else is
>> shorting out
>> > the plate supply
>> > either.
>> >
>> > Does anyone have any idea what might be going on here?
>> >
>> > Many thanks - Brian Carling, AF4K
>> >
>> >
>> >
>> > _______________________________________________
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>> > TenTec at contesting.com
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>> >
>>
>>
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>
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