klem kedidelhopper wrote in message
...
I have an old MFJ SWR meter with a built in counter. It has an LCD
display to read frequency and it uses a small 2 inch korean made
plastic analog meter to read SWR. I keep this unit in my service truck
wrapped up, however it may have gotten jarred because the unit still
works fine but all of a sudden mechanical zero is up about ten percent
of full scale.

There is no zero adjustment accessable through the front of the
instrument. This is a nice little unit however to adjust mechanical
zero you have remove the analog meter and open the case. This requires
complete disassembly of the entire instrument and it is a real pain.

I did this and opened the small meter and adjusted mechanical zero.
This is a simple procedure however the problem is static electricity.
Depending on how I hold this meter, touch it, rub my finger or even a
piece of cardboard near it, mechanical zero may shift. At times I
think that I have it zeroed and I close the case up only to find that
zero has shifted. Then I touch it wirth my finger and zero will
sometimes shift again.

So the problem is that I don't know if after I touch this thing if It
is totally discharged and it is really at zero or if static
electricity has influenced the position of the needle. This simple job
is really driving me nuts. It is very dry in the house and I'm sure
that this may have something to do with it, but I just don't know how
to compensate for this.

Obviously it is important that my adjustment is correct as there is no
access to it once the unit is re assembled. Can anyone offer any
advice? Thanks, Lenny.

Are you sure it is not erroneous electronics doing the sensing and actually
putting out some wavering DC instead of zero, rather than static
electricity. Monitoring terminals of meter with a DVM say