[Johnson] Bigger ain't better

[Glen Zook]

The Valiant (Ranger, etc.) do not "like" the 6146B
tubes in general.  The 6146B/8298A is much different
from the 6146/6146A/8298.  It is unfortunate that RCA
called the 6146B by that name.  RCA originally said
that the 6146B could replace the earlier tubes and
give 33% more power.  Unfortunately, this did not "pan
out".  Heath, Collins, etc., all said originally that
the 6146B could be used and then had to retract their
statement.  When their supplier stopped furnishing
"normal" 6146 tubes Heath found 1 supplier that their
6146B tubes seemed to function OK (actually Heath
"picked and choose" tubes).  Heath stated that RCA
6146B tubes should never be used in their equipment!

Basically, the 6146B is very hard to neutralize in
circuits designed for the 6146/6146A.  Collins found
that the 6146B would actually burn up the
neutralization circuitry in the S-Line and KWM-2
series equipment.  Since the U.S. military wanted to
use the "new" 6146W tubes (any 6146W tubes manfactured
after mid 1964 are 6146B and not 6146A equivalents -
nothing was changed in the nomenclature to show the
difference!) Collins had to redesign the
neutralization circuitry so that either series of
tubes could be used.

It is possible to "mix" 6146 with 6146A/8298 tubes
since the only difference is the heater (filament). 
The 6146A/8298 has what is called the "dark heater"
which is better when the heater voltage varies
considerably like in commercial two-way FM units. 
Otherwise, the tubes are identical.  But, NEVER mix
6146B/8298A tubes with the 6146/6146A/8298 tubes. 
This is really asking for trouble!

To read the article on the 6146 family of tubes that
was in Electric Radio and in the Collins Collector's
Association newsletter go to either of the websites
listed at the end of this message.

Glen, K9STH

 
--- "Kenneth D. Grimm, K4XL" <kgrimm@adelphia.net>
wrote:

I'm not a Valiant expert, but in some rigs the version
of 6146 used can make a big difference.  The manual
calls for plain 6146's. You don't happen to have
6146B's in there do you?

=====
Glen, K9STH

Web sites

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

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