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Re: [TowerTalk] More possible RCS8V problems

To:, Kelly Johnson <>
Subject: Re: [TowerTalk] More possible RCS8V problems
From: Jim Lux <>
Date: Tue, 05 Dec 2006 10:11:18 -0800
List-post: <>
At 08:33 AM 12/5/2006, Joe Giacobello wrote:
>Some time ago, another correspondent on this or a similar list said that
>the relays in the RCS8 were self-cleaning.  Up until that time I had
>been doing an annual PM by using a burnishing tool on the contacts.  Are
>you guys saying that they are not self-cleaning and do require periodic

I don't know if the RCS-8V relays are self cleaning; since they're a 
MFJ custom part, there's no data sheet to go look at, although an 
inquiry to Tom, W8JI, might be productive on this point, since he's 
probably seen more of these relays than I've had hot dinners.

There are other relays that have been mentioned on this list which 
ARE standard parts, and for which the datasheet says what the behavior is.

To be honest, I'm not sure precisely what makes a contact self 
cleaning, at least by looking at it.  There needs to be some lateral 
wiping action, but I suspect it doesn't take much. The overall 
mechanical slop in the mechanism, in combination with the contact 
surface being slightly convex, might be all you need.  In a high 
current contactor (a starting relay for an airplane), the cleaning 
was accomplished by setting the contacts at a slight angle, so every 
time it closed, the copper ring that served as the contacts for the 
armature rotated a few degrees. A very clever scheme.

The contact material also has something to do with it.

Jim, W6RMK


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