Re: [Elecraft] OT: Keying contacts - Clairification
My Bencher BY-2 paddle has gold-plated silver contacts. The contacts don't wipe. The paddle is 21 years old. The contacts have *never* been cleaned, and the paddle works great. 73, - Rob W7GH On Mon, 30 Jul 2007 15:09:55 -0700, Stuart Rohre <[EMAIL PROTECTED]> wrote: The contact area is a high stress point of pressure, Gold is a soft metal and actually can develop films that inhibit good conduction, unless the contact "wipes" so as to be self cleaning. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] OT: Keying contacts - Clairification
Keys almost universally would have silver contacts. Silver is one metal whose oxide is conductive. The contact area is a high stress point of pressure, Gold is a soft metal and actually can develop films that inhibit good conduction, unless the contact "wipes" so as to be self cleaning. Bronze is not as yellow as gold, visually. Bronze is not suited to switch contacts. Brass is sometimes used as cheap switch contacts, but alloys are often what you see that have a yellow color. Brass lends itself to having the silver contact welded or riveted to the brass base piece. The war surplus J38 keys were an example of brass conductors for the electrical paths to the contacts and a harder metal for the contact points. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] OT: Keying contacts - Clairification
What if they are 'gold plated' contacts-- does this change the scenario at all? On another note-- how does one tell the checmical makeup visually between bronze, gold, etc.? - Original Message - served to help keep them clean. Modern very low voltage/low current keying circuits don't do that and the contacts easily become intermittent as they collect a coat of oxides and dirt. Such contacts need no such delicate care as perhaps modern contacts might, although it'd be foolish damage them further needlessly. (Some old keys do have silver contacts which should be treated with care, especially if they're plated and not solid silver. Silver oxide is a good conductor, so even if they appear black they are still good electrical contacts. If they become intermittent it's not because they are oxidized but because they are actually dirty with a film covering the silver. Very gentle wiping should restore good contact.) ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] OT: Keying contacts - Clairification
Kent K9ZTV, made the point off-line that burnishing (rubbing to smooth or polish) contacts on modern keys might not be a good idea. He observed that any abrasive rubbing or polishing might damage special finishes or alloys that the manufacturer may have used on them. I was speaking of my half-century old keys that have brass (or bronze) contacts that have been repeatedly ground and burnished to remove pits and burns caused by arcing when keying high voltage lines in old transmitters. As John mentioned, a reasonable current through those contacts actually served to help keep them clean. Modern very low voltage/low current keying circuits don't do that and the contacts easily become intermittent as they collect a coat of oxides and dirt. Such contacts need no such delicate care as perhaps modern contacts might, although it'd be foolish damage them further needlessly. (Some old keys do have silver contacts which should be treated with care, especially if they're plated and not solid silver. Silver oxide is a good conductor, so even if they appear black they are still good electrical contacts. If they become intermittent it's not because they are oxidized but because they are actually dirty with a film covering the silver. Very gentle wiping should restore good contact.) On my old keys with their bronze contacts, burnishing is definitely in order if nothing else works and they've survived that treatment hundreds of times over the decades. Recently I've found that De-Oxit does the job even better as I described. If I bought a brand new key I'd check with the manufacturer about how they recommend cleaning the contacts because, sooner or later, they're sure to need it. Ron AC7AC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
