"Jimmie D" wrote in message
...

"Antonio Vernucci" wrote in message
...
Aside from that, there is no need to be concerned about a meter
reading for a receiver that is turned off. In short, any attempt to
force a mechanical zero would be negated by the "electrical zero" set
and S-9 calibration.

Yes, I agree that is in principle there is no need to be concerned about
a meter reading for a receiver that is turned off. But I am instead
concerned about that, because I like to have all my equipment in perfect
order, and a meter that does not stay on its zero when the radio is
turned off is something that I dislike and anyway wish to fix.

If I would not have had such requirement, I would not have put the
question because it is fairly evident that, when the radio is on, the
zero can be adjusted by means of the control indicated in the manual. All
old receivers have a zero control for the S-meter.

Moreover, the same problem anyway occurs for the RF output meter of the
matching transmitter (Hallicrafters HT44), which is of the same type. But
in the HT44 there is no electrical zero adjustment control, so the only
way of zeroing the meter is to open it and adjusting it mechanically.

By the way, in the meantime I have found the way of zeroing the meter, so
it is no longer an issue.

73

Tony I0JX

A lot of meters dont "zero" on purpose. This area of the meter is
inherently inaccurate so they are biased off of this point either
electrically, mechanicanically or even magnetically on purpose. Forcing
these meters to do otherwise isnt always making them"right". Unless there
is some indication that there is an inaccuracy with the meter and zeroing
will help it is best left alone. For example I have a linear scale
capcitance meter that must be"zeroed" at about 2pf for it to be accurate
on the rest of the scale. Perhaps one day I will solve this problem by
replacing the 50uA meter movement with a digital meter but it has served
me well for 30 years so I think I will leave it "as is" for now. I guess I
could make it "zero" on power off by applying a bias voltage to the meter
when it is on to slightly move the meter off the peg but attempts to do
this have shown that it would significantly complicate the circuitry and
comprimise accuracy.

Jimmie

I hope Antonio never comes accross a device with a bolometer. It would make
his life miserable.