[TenTec] Centaur Tubes odd ones in parallel

[Rick - DJ0IP / NJ0IP]

Kris,

When the tubes are not matched, what can happen is that one of the tubes
hogs more than its fair share of current - thus working harder than the
others.  Without individual meters to monitor the status of each tube, you
really can't know, other than noticing that the plates of one tube get red
sooner than the other.

So what "can" happen is, even though everything looks OK on the meters and
output power seems about right, one tube can be working harder - too hard,
and eventually burn up.

So yes, there is a risk, but what do you have to lose.
As it is the only alternative is to purchase a new matched set of 3.

What I would do is try it, at first running slight reduced power, and try to
watch the tubes.  I guess that is impossible without removing the cover and
I do not want to tell you to remove the cover and operate it (but that's
what I would do).  It is extremely dangerous to do that.

There is no 100% guarantee but as long as no one tube is glowing red while
the others are dark color, then you can assume it is OK.  

Next:  Gradually increase the power level until about 100w below the normal
maximum rated power and use it like that for as long as you can.

It's worth a try but if you have to remove the cabinet to observe the tubes,
keep in mind that it is a dangerous try.  Make sure there are no children or
pets in the room with you when you do that.

Do this at your own risk.  Don't do it alone if you are not technically
competent in working around high voltage.

Gud luk.

73 - Rick, DJ0IP
(Nr. Frankfurt am Main)


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of
km2km at twc.com
Sent: Tuesday, March 31, 2015 9:40 PM
To: tentec at contesting.com
Subject: [TenTec] Centaur Tubes odd ones in parallel

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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