Interesting Alek and thanks for the input. Have you come up with a specific
resistance for the various 572B amps rhat would make it easier for others?
Around here the 120/240V lines can vary from about 118-126/236-252 at times
due to population increase and frequent storm rebuilds along with rerouting
distribution.
I have Liberty Utilities fairly well trained by now to keep the pole pig tap
across the street at 236-242. Increases lighting life also.
At one time there were at least 3 Chinese 572B producers. Except for
Shuguang the others didnt want the headaches of dealing with hams and
concentrated on the Audiophool market where profits were much higher.
I picked up a nice variety of resistance wire from a surplus electronics
shop about 40 years ago to deal with Dentron and others. A Clipperton L,
MLA-2500, and DTR-2000L get rotated thru the vintage TX benches, mostly on
AM and a little CW and SSB.
Be very sure to use a TRUE RMS meter for measuring right at the tube
sockets. Most of the cheap imports dont qualify. I currrently use a military
surplus Fluke FM76 from when they dumped a load on the market many years
ago.
Carl
Ham since 1955
----- Original Message -----
From: "Alek Petkovic" <vk6apk@bigpond.com>
To: <amps@contesting.com>
Sent: Friday, August 20, 2021 10:08 PM
Subject: Re: [Amps] 572B/T160L tube class C
Over the years, I've imported around 200 572Bs from China.
They are definitely not as good as the US ones but they have proven to be
very serviceable, when treated right.
The single biggest proviso that I drummed into everybody that I ever sold
them to is to make absolutely certain that the filament voltage stays at
6.3V. The Chinese tubes fail very quickly with filament voltages of around
7V+, which are the rule in both Yaesu, Ameritron and Dentron amplifiers
when connected to Australian 240V+ mains voltages.
It is a very simple thing to add appropriate resistance to the filament
circuit to bring the voltage back to 6.3V. I've modified very many amps in
this way for many hams. The result has been that all those amps are
running happily on Chinese tubes, which are lasting many years.
73, Alek, VK6APK.
On 21/08/2021 8:00 am, Stan Gammons via Amps wrote:
I agree. I've had so so luck with the Chinese ones. They are nowhere
near the quality of the American made tubes. When America made lots of
tubes; I think we made the best tubes in the world. But, I'm a bit biased
:)
73
Stan
KM4HQE
On 8/20/21 6:52 PM, Carl wrote:
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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