[Drake] TR-3 S-Meter Short

[Glen Zook]

Actually, in a transceiver the meter is usually used
for "S" Meter functions as well as reading amplifier
current, etc.  A meter is a meter!

Also, I'm not looking at a TR-3 schematic right now,
but the vast majority of tube type equipment actually
read cathode current which includes the screen current
as well as the plate current.  Often there are several
low value resistors in parallel off of the cathodes of
the final amplifier tubes that serve as a meter
"shunt" as well as taking the cathode to ground. 
Often these change value.  Sometimes they go high in
value which causes the meter to read high, and
sometimes they go low in value which causes the meter
to read low.  I haven't worked on that many Drake
units for a while, but both the Collins S-Line and the
Heath SB-Line have these resistors go bad all of the
time.

It is much more common for a meter to "open up" than
go "short".  Sometimes there is an internal "shunt"
that does "short out".  Also, check the connecting
"studs" on the back of the meter.  I have seen meters
that have a metal back and these "studs" are supposed
to be insulated by "feed through" insulators of some
type (sometimes just a thin piece of paper).  If
something happens to the insulator then the meter
could appear to be shorted.

Glen, K9STH


--- Rob Matherly <kc0bom@arrl.net> wrote:

Checked both meters, they move.  Checked my meter,
it's goofy. :^)
 
Aside from that, I'm supposed to be looking for a
shorted Amp meter, not S meter.

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