[Amps] 572B/T160L tube class C

Sat Aug 21 12:43:29 EDT 2021

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 at bigpond.com>
To: <amps at 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 at ac0c.com>
>>> To: <amps at 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 at uky.edu>
>>>>> To: <amps at 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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