It's all about wetting current. On a building site machine design I used 30mA of dc and a level detector to sense when the switch had been pushed and they lasted years. A few pA from digital circuits is often not enough to wet precious metal contacts which are open to the ambient. Try cleaning fluid before using a diamond tipped polishing tool. Once that thin plating is gone, it will give even more problems. I seem to remember German silver as a good, hard contact material. Look at the technology of relay contacts.
David G3UNA > > > On Sep 4, 2012, at 7:42 AM, Lee Trout <[email protected]> wrote: > >> ...I have noticed that my Begali is quite sensitive to dirty contacts. >> On my >> Begali, intermittent operation is a sure sign the contacts need >> cleaning... >> > Hi Lee, > It seems you're correct. I switched to my hex key and the problem went > away. Back to Begali and it returned. For example my call becomes KAJ.. > and 73 becomes 7V as it delays on the dash. > I never suspected the key since I have been using it with the CW Machine > with no problems. Perhaps one draws more current? > Also, my K3 is in my new radio room, a finished family room 1/2 below > grade and with much higher humidity, been from 45 to 70% as I run the > dehumidifier. Just wondering if this may be the cause. The CW Machine is > upstairs with AC and thus very low humidity. > Last, how should I clean the contacts? I think with just a strip of paper > but know I must be careful. Also the Leonessa has the contacts stacked > vertical with dash on bottom and hard to reach. > > Thanks, > Don KA1KU ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
