At 11:58 PM 4/9/2008, Joe Subich, W4TV wrote:
>
>Unless the newer tubes are designed for higher plate voltages
>the 572B would be a safer choice. However, I don't see any
>really reliable 572B. I would certainly would not use a generic
>$39 Chinese 572B.
>
>73,
>
> ... Joe, W4TV
>
There are not any really reliable 572Bs, Joe. Trust me. I and
many other have looked. The Taylor name was bought out and they are
now made China. You can't get an RCA or a CETRON 572B/T160L unless
it is 25 years old. Penta Labs are also made in China. (As I type
this I am holding a "PENTA LABORATORITES, INC." 572B in my hand that
says "CHATSWORTH, CA" on the base, and under that is printed "MADE IN
CHINA." Svetlana no longer make transmitting tubes (try to find a
4CX800A, the heart and soul of ACOM -1000/2000s, QRO Technologies,
EMTRON and one of the newer Alphas -- the best you can get is an
equivalent NOS GU74b EX:Soviet Union military tube . . . but that is
another issue.)
As I said 2-3 times, there are absolutely no glass transmitting
tubes made in North America any more. This includes 811As, 572Bs,
3-500Zs, etc. They might say Taylor, Marshall, Penta or lots of
other things on them, but they also have PRC stamped on them. PRC =
People's Republic of China. I never made the case that currently
available 572Bs (new or NOS) were reliable when used at their design
specifications. They are not. They are no better made than
811As. They do last forever when run at a 1500-1700 plate voltage
because they are designed for 2500-2700 volts. That is why, and only
why, it is a good idea to use them in place of 811As.
73/DX Paul VE1DX
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