[TenTec] Failure Modes for 811a tubes? Centaur

[Steve Berg]

I just unplugged the amp, shorted the B+ and carefully reseated the 
tube.  Now, it works again.

Kris, the only time mine has blown fuses was when I inadvertently kept 
the bandswitch on 40 and tried to transmit on 20 meters.  I replaced the 
fuses, and it worked fine again.

I am not used to running such an amp.  I have had and still have plenty 
of tube type gear, but with the exception of an ancient Motorola quarter 
kilowatt 1 range hi-band base station, have always run less than 200 
watts.

Steve WA9JML



On 10/17/2013 7:46 PM, Kris Merschrod wrote:
> Ok, Steve has started a thread of interest to me.  I have a Centaur -
> relatively new set of 811As  - It blew fuses, I replaced the fuses and
> it ran for a few days.  Then it blew the fuses again.
>
> Steve, did your Centaur blow the fuses?
>
> I am getting up the gumption to try to guess which is the fuse that
> shorted (my hypothesis) and then pull it and put in another set of
> fuses.  There must be a better way.  Suggestions?
>
> Kris KM2KM
>
> ----- Original Message ----- From: "Steve Berg" <wa9jml at frontier.com>
> To: <tentec at contesting.com>
> Sent: Thursday, October 17, 2013 7:47 PM
> Subject: Re: [TenTec] Failure Modes for 811a tubes?
>
>
>>
>> I bought a nice Centaur amplifier from a list member a few years ago,
>> and finally got around to putting it on the air.  I took out the 572B
>> tubes that were installed in the amp, and put the original 811A tubes
>> in there so that I would be less likely to blow up by 600 watt
>> autotuner. I have since bought a new 238C tuner from Ten Tec.
>>
>> It was working fine, until the net last Sunday.  Suddenly, the output
>> power dropped.  I noticed later that the heater in the center tube was
>> out.  I cycled the power switch, and it came back on for a while, then
>> went dark again.  I have two sets of 572B tubes for the amp, but I am
>> curious about this being a common problem with 811A tubes.
>>
>> Any pointers?
>>
>> Steve WA9JML
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