[Boatanchors] 6146 folklore

[Glen Zook]

And I have seen just the opposite!  Many rigs that
don't like the 6146B and a relative few that do like
it!

That is why I say to watch the neutralization (if the
rig has that capability).  If the rig neutralizes OK,
and if it holds the neutralization, then certainly go
ahead and use the "B" and "W" series.  But, if any
instability happens, then go back to the earlier
tubes.

In addition, you really should use some type of
wavemeter (or GDO in the wavemeter position) to search
for VHF parasitics if you use the "B" series tubes in
place of the earlier versions.  You might be very
unpleasantly surprised at the spurious emissions that
the "B" series is putting out!  Unfortunately, the "B"
series is much more prone to the generation of
spurious emissions especially in the VHF range.  Often
that doesn't really show up readily on the meter
readings!

Also, although not in amateur service, but in
commercial service, replacing the 12 volt equivalent
of the 6146 / 6146A (6883 / 6883A / 8032) with the
6883B / 8032A / 8552 (12 volt equivalent of the 6146B
/ 8298A) in the Motorola Motrac series you WILL have
problems and problems in a hurry in those rigs that
were not designed for the "B" series tubes.

Again, Collins had to redesign the neutralization
circuitry in the S-Line and KWM-2 series so that the
"B" series tubes could be used.  Without the
modification at least 9 out of 10 units had serious
problems!  That, I believe, in itself shows the
problems that can happen with the "B" series!

As I have said before, many amateurs have not had any
problems using the "B" series in place of the earlier
versions.  But, many many more amateurs have
definitely had problems.  As such, I seriously caution
anyone who uses the "B" series in place of the earlier
versions to proceed with caution.  If the "B" series
works properly in their equipment, then that is fine. 
But, if the "B" series doesn't work properly, then
they are in for a lot of problems (including damage to
the equipment) if they persist on using the "B" series
tubes.

There is no shortage of the earlier versions of the
6146 family although the "W" versions are sometimes a
"bit" cheaper and the fact that most of these are the
"B" equivalent does cause some concern.  However, if
the purchaser of the "W" types knows what to look for,
and if they have problems with the "W" types go back
to the earlier versions, then they will not damage
their equipment, put out spurious emissions, etc.

However, the problems with using the "B" series tubes
is NOT an "old wives' tale"!  It is a real situation
that requires attention to be paid by those who are
trying to substitute tubes.  Sometimes they work fine.
 But, many times they don't!

Glen, K9STH


--- john <johnmb at nc.rr.com> wrote:

I've heard this story about 6146B/Ws over and over,
yet my first hand experience bears it out only in one
rig, that being a single HW101.

=====
Glen, K9STH

Web sites

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


		
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