KXPD3 Paddle Intermittent - At the hinge-posts ?

Posted by AB3SX on Jul 25, 2014; 7:23pm
URL: http://elecraft.85.s1.nabble.com/KXPD3-Paddle-Intermittent-At-the-hinge-posts-tp7591582.html

Good afternoon, Gentlemen -

I have been experiencing intermittent contact problems on my KX3 paddle for weeks now. ( I have read all the experiences on the group, and tried those suggestions.) Sometimes I would gain temporary relief from dis-assembly, cleaning, reassembly, but the problem always returned.

The main symptoms are "missing dit"; with easy wrist-rolling from side to side, I suddenly come up with no dit where one should be. I learned I could minimize this problem by "man-handling" the levers, but this was tiring ( that is, forceful lever movements seemed to solve the problem of intermittent contact ). This seemed strange, since I could clearly "feel" the movable contact stop on the post, even though no electrical contact was completed.

Well, something FORCED me to have a better look into what was happening, and I thought I would see if any of you have been experiencing this same problem. I have recently been operating the KX3 set up as "hand-key" and the automatic creation of proper length dots and dashes is no longer present to cover up the frequently intermittent contact. So today, I followed a hunch and connected two clip leads to provide ground from the chassis to each of the movable levers. Sure enough, this put an end to the intermittent operation. I repeated the test several times, and each time the intermittent would appear without the clip leads, and disappear once the clip leads were reattached.

I followed this up with a power-off resistance measurement from each of the movable levers to the chassis and, sure enough, LARGE resistances were found. Depending on the amount of pressure exerted on the lever ( to load the swing-lever/pin joint, the resistance could be varied from 8000 ohms to 1200, 800, all the way down to 1.3 ohms ). I went further to check the resistance to chassis from the knurled-bolt KXPD3 fasteners ( 1.0 ohm ) and the resistance to chassis from the top-place of the KXPD3 ( 1.2 ohms ). Only the last part of the path to each lever seems to be involved in the high-resistance problem ( the vertical hinge that supports and grounds each lever ).

So, AT-LAST, my problem has been located. I am wondering if this has happened to anyone else with the KXPD3? ( It looks like most of such discussion peaked and went away in year 2012, so I am guessing I am the only one with the problem ).

Love my KX3, and can't wait to get this one little quibble quashed :)

Jerry AB3SX