I have used about 8 of the Chinese 572 specifically for torture testing in
RTTY service and I can say without qualification that the plate dissipation
limit (IIRC 160w) is not something which will keep the tube in long service.
But whipping the hell out of these tubes in AM/FM/RTTY service with all the
guns blazing is not the common application.
I would expect the current breed to give long SSB service as long as tuning
is done properly and kept to a minimum. For CW, almost as well. From
there, it goes down hill fast.
Comparing them with prior generations makes no sense because there are
virtually zero NOS old tubes remaining. You either buy the Chinese (through
some direct or distribution method) - and that is the only source available
and take what service life you can get. Or you can flip to another tube
type at some considerable amount of work and expense.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message-----
From: L L bahr
Sent: Thursday, May 02, 2013 5:00 PM
To: amps@contesting.com
Subject: Re: [Amps] 572b
If quality control is so poor, how do you test for longevity or robustness?
Just checking the emission when new may have nothing to do with longevity.
I'd like to know how well a Chinese 572B will hold up compared to a Cetron
572B. I wonder what short cuts the manufacturer has taken in production
when many new ones go out the door with poor emission. What else is wrong
with them? Maybe it's time for these amplifiers to be retrofitted with
other type tubes.
Lee, w0vt
----- Original Message -----
There's no doubt that the manufacturer is the problem, but since they are
the only one making them and most Ham's just need a few, a reputable
distributer is very important in the supply chain. He tests them before
selling them to be confident that they worked when they left his facility,
that is one of the reasons he is considered reputable. It costs more, but
he must becompensated for his time. A reputable dealer is paramount in
buying a tube you know has a decent chance of being good, andis the one
thing you can do anything about-choose who you buy from !! Cheers, Matt
73AD7XN
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