Hi All
I always use the corner of a dollar bill, not very abrasive
& works great (now you know why the corners are missing!)
Mark
Tom Rauch wrote:
>
> Date sent: Tue, 23 Feb 1999 16:00:29 -0800
> From: dlhough@vegas.infi.net
> Subject: Re: [TowerTalk] burnishing tool
> To: Scott M Cronin <lefty@bc.seflin.org>
> Copies to: "towertalk@contesting.com" <towertalk@contesting.com>
>
> >
> > Also might check out an auto parts supplier or a Sears store where
> > they keep the tools. That's where I got mine. It's also possible to get
> > an 800 or 1200 grid emery paper and do the job.
>
> Agggghhhh!!!!!!!
>
> NEVER ever ever use anything abrasive on a plated relay contact!!!
>
> The contacts are either gold flashed, or silver flashed, with various
> alloys added to modify the surface for different current requirements.
>
> If you remove even a few tenths of an inch (meaning ten-
> thousandths in plating slang) of surface, you'll absolutely destroy
> the alloy that keeps contact resistance low.
>
> The MOST you should ever use on a plated relay contact is
> something about as abrasive as cardboard. I use a thin cardboard
> like off a matchbook cover soaked in toluene, xzylene, or one of
> the other nasty solvents that evaporate without any residue to
> clean crud out of the contacts.
>
> This does not apply to starter solenoids, or other hundred ampere
> non-plated contacts. They can be cleaned with a grinding wheel
> since they are not plated, but don't try that on gold or silver alloy
> flashed contacts typical in low or medium current relays.
>
> As long as I am on the box, relays get "dirty" for two main reasons.
>
> 1.) They are not plated.
>
> 2.) They have had the plating ruined by hot switching or "cleaning".
>
> 3.) They have debris trapped on the contacts.
>
> 4.) They aren't in an application where they carry a required
> minimum current that "wipes" the contact.
>
> Number four is a major problem with amplifier relays. The receive
> contacts technically require a different alloy than transmitting
> contacts, because one carries virtually no current while the other
> carries several amperes. Since they are in one relay, your stuck
> compromising. An antenna relay is the same.
>
> When they "get dirty", and they usually will because the material is
> a compromise, all they need is a VERY light wiping (like with
> cardboard) to remove surface contamination. Just be sure to blow
> any paper fibers out with air or freon when you are done, and
> NEVER coat the contacts with any "stuff".
>
> What type of relay is it that is the problem? Maybe it's the wrong
> type? Relays rated for hot switching higher currents, while
> impressing customers, make very poor antenna relays. They are
> great for starting motors, but not designed to maintain low contact
> resistance under conditions of low current flow.
>
> 73, Tom W8JI
> w8ji@contesting.com
>
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