13 Apr
2005
13 Apr
'05
4:49 p.m.
IIRC one of those 'polar relays' is not-
it's actually the QBF
message generating coder-a very clever little electromechanical device
with a "disc" memory. And that spiral timebase was something else -
Correct. The 'disk' is a circular PCB that has the QBF message stored in
the trace pattern. It's read out by a set of brush contacts that touch
the pads on the PCB as the latter rotates.
The manual I have for my TDMS (and which I can't instantly put my hand
on...) has a section in the back covering dismantling, assembling, and
aligning this 'coder'.
Although it's the same can and plug base as the polar relay alongside it,
the locating pins are swapped round (one being larger in diameter than
the other) so you can't get the the wrong device in the socket.
-tony