Hallicrafters HA-1 TO Keyer

Al Waschka awaschka at PALMNET.NET
Thu Sep 17 23:37:56 EDT 1998

A friend once called this kind of problem "FIB" for "Foot In Bucket".
Remember the cartoons where a character steps in a paint bucket and
limps around chasing his nemesis?

I am having difficulty after cleaning up a TO Keyer.  Prior to cleaning
the chassis I removed the tubes.  There were 4 12AU7s and two voltage
regulators.  I failed to notice that the manual said three of the four
should be 5963s and consequently didn't pay any attention to which
sockets I got the 12AU7s from.  A 12AU7 is a 12AU7, right?  When I put
it back together, it didn't work right.  I checked the tubes and found
one bad, but the reason it was bad was that a pin was broken and came
off when I removed it from the tester.  I had another 12AU7 (which also
checked good) so I put it in.  The keyer comes the closest to working
with only one of the four tubes in the V3 posistion, the divide by two
flip-flop.  With all other tubes it is only possible to get dots, faster
dots (the flip-flop is oscillating) or a continuous dash (but not
self-completing dashes) by adjusting the balance of the flip-flop as
specified in the manual.  With one of the 12AU7s in the V3 position it
almost works, but often the first character sent when the dash paddle is
pressed is a dot.  If the paddle is held down, the subsequent characters
are dashes.  In some settings, the number of dashes is limited, i.e. the
keyer starts sending a continuous dash.

My questions are:

1.  Anybody had this problem before with a TO Keyer?  If so, how did you
fix it?

2.  What is the difference between a 5963 and a 12AU7?  Why would
Hallicrafters specify 5963 for 3 of the 4 12AU7s in the keyer?

Thanks for any assistance any of you might be able to render to get my
foot out of this bucket.



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