I ran into the same deal with my AL-811 amp. I had two NOS RCA tubes and a GE
tube in it. Amp output was full power and all seemed well. I decided to buy a
match trio of Cetron tubes from Surplus Sales.
I installed the Cetrons and noticed the plate on the GE had the oval mark on it
typically of an 811 indicating over heating. The two RCA tubes looked fine. I
chalk it up to non-matched tubes.
-Eric
W9WLW
Sent from an iPhone
> On Apr 1, 2015, at 9:08 AM, <km2km@twc.com> <km2km@twc.com> wrote:
>
> Here's the result - first w/o tubes I fired up the Centau. All lights on and
> not blown fuses. pit in one tube that did not look bad - blew the fuses -
> tossed that tube out, alonng with the one that had white dus in what looked
> like a volcano in the stem. Put in last tube - all fine lit up. So, tossed
> in the two Svetlanas with the sole Taylor. The mixed troika lit up and gives
> full power. This AM ran it at 3/4 power (a tad less than 75 watts in) and
> had good reports and it was a happy camper (so was I).
>
> I'll order a set of matched tubes today so when this troika blows I will be
> able to start fresh - but, in the meanwhile, what is there to loose?
>
> Many thanks for the suggestions,
>
> Kris KM2KM
> MERSCHROD
> 123 Warren Road
> Ithaca, NY 14850
>
> ---- km2km@twc.com wrote:
>
> =============
> Ok, guys, here is the scoop.
>
> My trusty Centaur seldom needs to be re-tubed, BUT now I have two pairs of
> tubes, one pair Taylor, and the other pair Svetlana because over time one
> tube left the troika for the electronic dump. Yes, matched tubes are the
> ideal, but having a couple of pairs sitting around doing nothing for me and
> no foreseeable makes me wonder. Just what would happen if they were a mixed
> troika. That would leave one tube in the bin ready for another time.
>
> Any ideas on dire consequences?
>
> Many thanks,
>
> Kris KM2KM
> MERSCHROD
> 123 Warren Road
> Ithaca, NY 14850
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