Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

 
 
LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #1   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 412
Default mechanical zero on a small meter

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.
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Electricty to flat: Powercard meter, coin meter, or what? Frank UK diy 21 April 20th 07 08:42 PM
UPDATE: 11 Meter to 10 Meter Yagi Antenna Conversion Brad Electronics Repair 0 June 19th 06 06:37 PM


All times are GMT +1. The time now is 12:21 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"