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K3SGM
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Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

Break In period for Chinese 572B tubes

Got a new Ameritron AL-572 1.3kw amplifier for Christmas, but have not powered it up yet.

Arrived with unmarked(alleged Chinese MFG) 572B tubes.

The old Cetron or Raytheon tubes are all but a memory at this point, and even the Russian Svetlana/SED tubes are supposedly made in China.

What would be a good burn-in time before applying drive to the tubes??

I want enough time for the 'getter' to de-gas the tubes, but don't want to tempt fate and fry the grid circuit with a internal arc-over too early on.

Anyone have some experience with the appropriate burn in procedure for these tubes before I end up sending the amplifier back to Ameritron for unnecessary repairs??

This is my first real experience with foreign made power tubes, I never worried about these things with US made power tubes from manufacturers such as Eimac.

I was thinking about 24 hours with the filaments lit and 2800v plate voltage applied, then working up slowly from about 20 watts of drive after that initial time frame.

Digital
As-Salamu Alaykum
Premium Member
join:2000-07-24
Wickliffe, OH

Digital

Premium Member

I just asked my Dad he says 1 hour (10 being optimal) before applying drive to those. I have no idea how much experience he has with them though. He simply said that's a good place to start.

Hank
Searching for a new Frontier
Premium Member
join:2002-05-21
Burlington, WV

Hank to K3SGM

Premium Member

to K3SGM
Was there no information that came with the amp from the manufacture that recommended a burn-in period?

K3SGM
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Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

said by Hank:

Was there no information that came with the amp from the manufacture that recommended a burn-in period?
Ameritron is silent on the issue.

Some of their advertising still mentions "4 Rugged Ceramic based Russian 572B's".

That was related to the Svetlana / SED tubes they used to use, that I now read were a problem and no longer used by Ameritron.

Well I have 4 Brown Phenolic based unmarked tubes, and a quick call to Ameritron confirms that they are the correct tubes that they now ship with the amp, and there is no 'break in' procedure mentioned.

They do however recommend that I only purchase replacement tubes directly from them in the future.

I have read horror stories about various 'no name', supposedly Chinese manufactured tubes experiencing grid shorts and flash overs, and trying to find a brand new quartet of NOS US made tubes is either extremely expensive, or all out impossible.

I refuse to pay Ameritron double for their tubes, and I never treat any type of power tube as a plug and play device.

I always let new tubes cook-off any internal impurities for a few hours before applying drive, but it sounds like the currently available 572B's are a special case.

The amp runs the tubes at 2900v on standby, and 2500v fully loaded, but it sounds like many 'junk' 572B's are only rated at around 2300v tops, and if that is the case, running the tubes 600v over their maximum rating, it is only a mater of time until there is a catastrophic failure.

Just trying to find someone that has had any experience with these particular tubes, in this particular amp.

I hope I get many long years out of the initial set of tubes, but I want to break them in right, so I don't have any early failure problems.

I may go so far as to change the power supply transformer taps to keep the plate voltage below the norm for the first few months, and if there are no problems, I can gradually step it back up to the full rating.

73

Ender3rd
join:2001-07-15
Connecticut
·Frontier FiberOp..

Ender3rd

Member

I realize the original post regarding this was over a month ago, but I wonder how you made out with your Chinese 572B's?

Digital's advice is roughly what I have heard, 10 - 12 hours with the filaments lit and the plate caps lifted off the tubes.

Then powering up with the plate caps installed and letting it sit again for a few hours. Then dumping the output into a dummy load and applying a small amount of drive to load it at less than half the amp's rated current rating for several minutes.

I would most likely treat it very nicely for the first couple of sessions, and if it behaves well things should be fine. I have a few broadcast pull 4-400's that I still rotate into my big rig and they have never complained when I bring them back to life this way. Keep in mind that they were removed from commercial service over 25 years ago!

73,

Rob W1AEX