[Heathkit] Troubleshooting my HW-101

[Glen Zook]

So that everyone on the list knows what is going on,
here is the text of the message that I sent to Ted:

GE normally used Sylvania manufactured tubes and
Motorola used RCA manufactured tubes.  The 6146B tubes
that Heath supplied towards the "end" of production of
the HW-101 were special "culs".  That is the
particular tubes were selected so that they did not
have the problems that the vast majority of 6146B /
6146W tubes had.  Frankly, I suspect that these "culs"
were tubes that didn't meet the specifications of the
6146B but could meet the specifications of the 6146A.

Now the TS series of transceivers manufactured by
Kenwood were designed using 2001A tubes.  Those are
the Japanese equivalent of the 6146B.

The 12 volt equivalent of the 6146B is the
6883B/8032A/8552 and RCA "cross branded" most of their
tubes with all 3 numbers.

The later Heath equipment has the 6146 heaters
("filaments") wired in series so it is VERY easy to
change these to a parallel arrangement and use the
6883 or 6883A/8032 tubes.  I have done this with quite
a few transceivers (including some Japanese
manufacture) so that the 12 volt tubes can be used. 
Because of all the 12 volt tubes that were made for
the commercial two-way market you can often find the
12 volt 6146 equivalents (all of the variants) for
considerably cheaper prices than the 6 volt versions.

Now you cannot make the heater changes on Collins
equipment because they are wired in groups of parallel
arrangements that can be put in series for 12 volt
operation.  Rewiring the heater circuits will upset
the balance which is necessary when using the Collins
equipment with a power supply that furnishes 6.3 volts
(which the 516F-2 power supply is designed).

Glen, K9STH


--- Ted Bruce <kilocycles at yahoo.com> wrote:

Ken, You and Glen have always been good for a wealth
of information; that's why I monitor this list.
 
On the 6146B issue, Bulletin HW-109 mentions
"reworked" GE tubes that may be marked 6146A or may
have 6146B etched in the glass.  Heathkit said those
are acceptable, and apparently aplied only to
Heathkit-supplied tubes.  Now, looking through one of
my printed bulletins list, I don't see any reference
to the GE-6146B being approved from some date going
forward.  It's on my main computer, I guess, which I
don't have access to right now during the move.  I'm
pretty sure I didn't make it up; I'm not that smart!
 
Thanks for the info on the additional checks, Ken, and
on the clarification of the Kenwood TS-rigs' finals
Glen.  My memory isn't what it used to be.









Glen, K9STH

Website:  http://k9sth.com

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