[TenTec] Centaur Tubes odd ones in parallel - finding and results

Wed Apr 1 09:50:12 EDT 2015

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 at twc.com> <km2km at 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 at 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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