The Chinesw 572B and 811 (it is NOT a real 811A, not even close) are mostly
all junk looking for a trash can. They sometimes let a good one sneak thru.
Best bet is to pay the freight for a real NOS Cetron or United Electronics,
the only USA real manufacturer who private labeled them for others.
----- Original Message -----
From: "Jeff Blaine" <KeepWalking188@ac0c.com>
To: <amps@contesting.com>
Sent: Thursday, August 19, 2021 10:33 PM
Subject: Re: [Amps] 572B/T160L tube class C
How much service do you expect from a new set of tubes? It's one thing to
know "it can do it, if I want" - but then not actually need the
capability. It's another thing if you are saying "I want to run a 572b
24/7 at full output."
About 10 years ago I was working on a SB200 which was initially setup to
run RTTY. I did quite a lot of profiling of those using the Chinese tubes
of the era. Watching very carefully to respect the Pd max of the tubes, I
found a typical 25% drop in Po over about 100 hours of testing. The
testing was typically 3-15 minutes key down 100% carrier per interval.
Plus on-band rag chew, contesting & DX (this was pre FT8).
Carl is about a million times more experienced than I am but I think maybe
the Pd spec vs. actual was a bit optimistic for the Chinese tubes I had
because this drop off seemed excessive. However my abuse of those tubes,
compared to typical ham use, was really bad. Also the SB200 positions the
tube horizontally which may be a factor as is the generally poor
circulation even with my augmented cooling.
In the end, I abandoned the 572b and went with the GI7T which was an
excellent performer by comparison although it required quite a lot of
changes to the SB200. Unless there is a specific reason to use the 572b,
if I were building a high duty cycle amp in the future, I would probably
want to use a metal/ceramic type tube instead of a glass one.
Good luck!
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 8/19/21 8:50 PM, Carl wrote:
That tube was designed for AM BCB service by Taylor but didnt catch on
there or for AM hams as the T-160L in the late 50's.
It was later bought by and designated the 572/T-160L for Unitrd
Electronics alone.
They couldnt keep up with demand and sold production rights to Cetron who
had a much larger production facility.
UE then became the 572A and Cetron the 572B. The step top (shouldered)
glass was Cetron and the round top was UE.
At some point the T-160L was dropped for both.
You may also find a 572B with the round top and the Cetron name, those
were built by UE as the demand was even too much for Cetron alone at
times....such as the SB-200 and the Clipperton L.
I have examples of both (no Taylor T-160L) as well as other versions
including OEM named such as Dentron, Waters, plus Raytheon, GE, and
several others who did not build their own. The top shape ID's the
source.
I cant remember ever seeing an actual T-160L spect sheet or the tube.
Carl
Ham since 1955
----- Original Message ----- From: "Fuqua, William L." <wlfuqu00@uky.edu>
To: <amps@contesting.com>
Sent: Thursday, August 19, 2021 8:56 PM
Subject: [Amps] 572B/T160L tube class C
I am looking for full power data for the 572B/T160L operating ICAS
class-c CW and AM.
The only thing I have found thus far is in an ARRL handbook, but it is
obviously the 811A specs.
Not the full 160W plate dissipation specs.
73
Bill wa4lav
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