No subject

[Glen Zook]

The 6146 or the 6146A will work fine.  The 6146B is
actually a different tube which may cause problems,
especially with VHF spurious emissions.  Also, the
6146B often will not properly neutralize.

NEVER mix a 6146B with either a 6146 or 6146A!  You
can mix the 6146 and 6146A since the difference is in
the heater design.  But, it is a big "no-no" to mix
6146B with 6146/6146A!  You are asking for trouble!

The 6146W tubes are sometimes the equivalent of the
6146 and sometimes the equivalent of the 6146B.  The
military did not make the change in nomenclature when
they went from the 6146A to 6146B.  Basically, any
6146W manufactured after 1963 is suspect of being the
equivalent of the 6146B.  RCA introduced the 6146B in
mid-1964.  The 6146W tubes started being manufactured
with the 6146B equivalent shortly thereafter.
However, various manufacturers did not immediately
change over.  It took up to a year before all
manufacturers were making the 6146B equivalent.  But,
as far as I know, there is no listing of just when
each manufacturer changed over.

There is no reason at all to get "matched" pairs of
6146 or 6146A for the SB-401.  The tubes are running
in parallel and you will not be able to tell any
difference in performance between a matched pair and
an "unmatched" pair.

Matched pairs can have a slight effect when the
amplifer is push-pull.  However, this is much more
prevalent in audio than in r.f.  The main thing that a
matched pair will do in an audio circuit is reduce
distortion.  However, the vast majority of people
can't tell the difference when listening!

Barry Wiseman at Electric Radio is supposedly
publishing an article on the 6146 family in the
January issue.  Electric Radio is a "specialty"
amateur radio magazine that caters to the "boat
anchor" users.

Glen, K9STH


--- ejforwood Jerold Forwood <ejforwood at MSN.COM>
wrote:
> Hi All,
> Sorry, I know this question has been answered before
> but it has only now become a problem for me.
> 1) Which is best final for a SB-401, 6146, 6146-A,
> 6146-B, or 6146-W and is it necessary to use a
> matched pair?
> 2) I have good drive from the SB-301 I am using in a
> transceiver pair but am getting low RF voltage on
> pin 2 of the 6CL6 and very low on the wire between
> pins #5 on the 6146's of which one is a 6146 and one
> is a 6146-B.


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