[Hallicrafters] PA Tubes

[Glen Zook]

This subject comes up almost weekly these days!

Most transmitters that were designed for the 6146 /
6146A / 8298 are NOT very happy with the 6146B / 8298A
and any 6146W made after mid-1964.  There are
exceptions in that a specific example of any
manufacture just might work OK, but the very next one
down the production line won't work!

Instead of going through everything that can happen,
the article that was in Electric Radio a couple of
years ago and was reprinted in the Collins Collectors'
Association newsletter several months ago can be found
on either of the websites that are referenced at the
end of this message.

Also, "matched pairs" of 6146 tubes are NOT needed in
any of the transmitters that run the tubes in parallel
(all of the boat anchor transmitters that I know of
run them in parallel and not "push-pull").  Frankly,
after just a few hours of operation the tubes are no
longer "matched" anyway.  None of the manufacturers
ever furnished matched pairs when the equipment was
new.  All that matching does is to increase the profit
for the tube seller!

In circuits (like some modulators) that operate tubes
in push-pull matching might make a very slight
difference in performance (like a little bit less
distortion in the audio).  But, again, at least 99% of
those who listen to the signal can't tell the
difference!

By the way, it is "OK" to mix 6146 and 6146A tubes
since the only difference is in the heater
("filament").  However, NEVER mix any of the earlier
versions of the 6146 tube with a 6146B.  That is
really "asking" for trouble!

Glen, K9STH


--- David Hallam <dhallam at RapidSys.com> wrote:

What is the conventional wisdom regarding the use of
6146B's or W's in the PA stage of a HT-32B rather than
6146's or A's?

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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