Hi, Tony

I have a "Shurite" brand iron vane panel meter, similar to what you describe.
The meter's zero adjust screw is connected to a semicircular metal disk
mounted at a right angle to the axis of the pointer shaft. There is no contact
between the semicircular disk and the pointer assembly. I suppose zeroing is
based on adding or counteracting residual magnetism in the fixed iron vane. I
don't see any torsion springs in the Shurite meter.

An iron vane meter was used in the Heath DX-35, and I remember the underdamped
response. You could practically monitor your sending by the sound of the
meter pin hitting the end stops.

73,
Ed Knobloch

Hi Ed,

yes, the meter is just as you wrote. I did not know the name "iron vane meter",
good to know.

Carefully examining the meter, I found it very similar to what you wrote. On the
axis I can see two parallel round disks (orthogonal to the axis) one at the axis
center and one at its extreme:

- the first disk is fixed to the meter axis, and part of it lies inside the
coil. When current flows through the coil, the disk (and the axis) rotates. I
presume that the magnetic properties of that disk are not homogeneous (maybe
half disk is magnetic and the other half is non magnetic)
- the second disk is instead not fixed to the axis. Its position can be changed
by a means of a screw placed at the axis end (just like the zeroing screw of
normal meters). I presume that also this disk is non-homogeneous. Rotating the
disk changes the meter zero. I tried and it works!

Thanks and 73

Tony I0JX