[Hallicrafters] HT-37 output tubes.

[Glen Zook]

Collins originally designed the KWM-2 series for the
6146/6146A/8298.  Then, after 1964 when the military
changed the 6146W from the 6146A to the 6146B without
changing the nomenclature, the S-Line units (including
the KWM-2 series) started burning up the
neutralization circuits when the 6146W equivalent of
the 6146B were used.  Collins had to redesign the
neutralization circuit and provide a kit to change the
circuitry so that the 6146B type tubes could be used. 
Also, the factory changed the circuit in all new
S-Line transmitters that were shipped.

You can tell if the circuit has been changed by the
fact that there is an air variable capacitor rather
than a ceramic variable capacitor.  There were other
components changed, but the variable capacitor is the
"clue"!

Equipment modified with the new neutralization
circuitry can use any of the 6146 family without any
problems.  Those that haven't been modified must use
the 6146/6146A/8298 series instead of the 6146B/8298A
series.

Collins shipped all the S-Line units with the
6146/6146A/8298 series and not the 6146B/8298A series
tubes installed as far as I know.

Glen, K9STH


--- Bob Rinaldi <w1cny at comcast.net> wrote:

Along the same line of inquiry, I've seen KWM2 units
with the various 6146 varieties.  Which variety did
Collins specify for the M2?


=====
Glen, K9STH

Web sites

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

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