The 572B tube.
By Merit Arnold W6NQ
November 13, 2014
The first 572B was made by United Electronics for a company called "Waters
Manufacturing".
The WATERS tube first showed up in the Heathkit SB200 amplifier c. 1964.
Soon, Cetron replaced United Electronics as the supplier and labeled their tube
572B/T160L.
The T160L is a throw-back to an early tube numbering scheme by Eimac, Taylor,
and others,
where the 160 is the plate dissipation rating and "L" identified the tube as
being low-mu.
Dentron Electronics later used the Cetron tube in their amps c. 1970's & 1980's.
Hunter and Ameritron also used the 572B.
At that time, Cetron was the only manufacturer of the 572B, and
RF Parts was the only remaining customer when production ceased in 1978.
RF Parts Co. chose to discontinue buying from Cetron due to inflated factory
prices.
The new cost would have made it necessary to sell the 572B at $125 each in 1979
dollars.
As it would have been a special production run just for RF Parts Co.,
it would require cash up front for a 2000 pcs. minimum order.
RF Parts Co. was a smaller company at that time, and demand for the 572B
was not so great as to warrant our investment.
In the 1980's, the Chinese factory Shuguang started producing the tube, which
we began selling.
Price was very attractive, and the factory began improving their production
during the first year or two.
In later years, the quality of the Shuguang tube became inconsistent.
To maintain quality, RF Parts and Ameritron instituted full 100% testing,
with any marginal tubes being shipped back to Shuguang.
I don't think Shuguang destroyed all of the returns,
salvaging some to sell to domestic dealers.
(I suspect that these tubes are now being offered on ebay.)
Shuguang ceased manufacturing the 572B tube in 2013.
When stateside supplies ran out, Ameritron and RF PARTS had no tubes to sell.
Going back to 1996, RF PARTS was able to import the Russian Svetlana tube.
This was not an exact copy of the U.S. tube, but one made from
available materials found in Russia at the time. Only one production run was
made.
It had a bit less dissipation capability, but otherwise was interchangeable.
RF PARTS found that a full 100% testing was also required for our acceptance.
Unfortunately, stock on the Svetlana 572B has long since run out.
About a year ago, RF PARTS approached different Chinese tube factory
to build a premium grade 572B as close to the U.S. quality as possible.
This tube would be manufactured exclusively for RF PARTS.
Evaluation of new materials was necessary to improve the tube design to the
level we required.
This took longer than we originally estimated, and several iterations later,
We put pre-production samples through an extensive evaluation.
During this period, the design and quality were finalized, and the
factory was given the go-ahead for production in November 2014.
The first production tubes should arrive at RF PARTS by early December.
All will be fully tested, with a portion subjected to extended transmit time
before the remainder are shipped.
RF Parts has pre-sold the first couple production runs to customers that had
placed firm orders with us.
RF Parts will re-open order acceptance for the 572B at a time to be announced
on or before December 19, 2014
_______________________________________________
BVARC mailing list
[email protected]
http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
