[Amps] 572B/T160L tube class C

[Jeff Blaine]

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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