Another technique to remove any debris that may be causing the meter to
stick, is to cut a tiny strip of double-sided (sticky on both sides)
scotch tape. Holding the tape with tweezers, work it in between the
armature and the outer core to pick up the debris. It may also be that
the pivot tension screw is too tight, causing the movement to bind. Get
a jeweler's screwdriver and slightly loosen the screw. Just do
everything carefully, plan each move and have plenty of light and a
magnifying glass.
73,
Bob WB2VUF
On 3/28/2012 6:48 PM, Stuart Rohre wrote:
> Steve,
> WELCOME to ham radio!
>
> Sticking meters usually have picked up a metal chip or dirt in between
> the moving pivoted coil and needle and the magnet core that surrounds
> the moving parts.
>
> It could also be dirt in the needle bearing pivot points.
>
> Use a strong light, like a bright LED flashlight, or Halogen light to
> inspect the area between the moving coil/pointer and the core.
>
> You may be able to blow out obvious dust and cobwebs with a camera
> squeeze brush/ rubber bulb device, with gently puffs.
>
> Or you may be able to take a sheet of printer paper, very smooth type
> and cut a ribbon of that to pass into the space between the coil and
> magnet core. But, first try to figure out what is binding the pointer.
>
> You can puff gently with your breath to drive the pointer up scale off
> rest point, and see if it only hangs up as it passes one spot.
>
> If you have a piece of metal or chip in the core of the magnet, you have
> to use the corner of a strip of printer paper to nudge it out.
> Only use tweezers when you can get at it on the outer magnet area, NOT
> close to the fragile coil.
>
> To do all this, you need to have the meter out of the rig, where you can
> rotate it around in your hands. Use photo cloth thin gloves to keep
> sweat and skin cells off the interior of the meter. Some meter cases
> are glued if plastic, others have screws and the plastic can be removed
> to gain access.
>
> The ideal meters to work on are the old round ones in metal cans where
> you can get the whole meter guts out with removal of three screws around
> the can.
>
> Hopefully, you can get into the meter and puff or blow out the foreign
> debris. Don't try an air hose nozzle! It will destroy the meter.
>
> If it is a very well glued plastic cased meter, you may have to find a
> similar meter to replace it, or one from a junked rig of the same model.
>
> 73,
> Stuart Rohre
> K5KVH
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.1913 / Virus Database: 2114/4898 - Release Date: 03/27/12
>
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|