[GreenKeys] Loop supply options

[Ron Boltz]

I thought I would add some recent experience with loop supplies.  I recently
picked up two more Kleinschmidt's to add to the collection.  I did not have
a TT-4A but I had to buy both machines as it was a package deal.  Put the
TT-4 on the bench and used a 1980's vintage Heathkit regulated adjustable
high voltage power supply for the loop.  Lots of mechanical issues but after
that I could not get good copy from the keyboard.  Every time I thought I
had it, typing RY's , it would garble again. So, decided to put in in the
active loop with the MD-522A and send continuous RY's from there so I could
have free hands to adjust the armature and range.  I easily had 100% copy!
Went back to the bench supply and junk prints.  Long story but the old
supply uses 6L6 tubes as the regulators and when the loop goes to space, the
voltage spikes up faster then the regulation can adjust.  I saw this on a
scope as a DMM  was not quick enough.  That sudden open circuit spike messed
up the selector magnet and armature going back to mark.  Worse when 2 spaces
are in a row. Never had this problem with a TT-76 or a TT-98 but those have
a different arrangement with bias so maybe that's it. Just a bit of
information, nothing suggested.

 

Ron Boltz

K3TZJ

 

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