[Elecraft] [K3] Keyer Pause

[David Cutter]

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 <troutcm at gmail.com> 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