[Elecraft] Kpa 500 problem when auxiliary cable connected ...

[Jorge Mejia P]

I had been successfully using my KPA500 with an Icom and a  K3 , alternatively with the use of the Key Line interrupter and a separate key line. 
Suddenly I cannot change bands on theKPA500  or go on Tx, even though the  auxiliary cable  is well seated and the Key line interrupter is well screwed to the K3 . The kpa500 works fine with the K3 alone, or when I disconnect the auxiliary cable from the K3 ,then I can change bands and use it with the Icom as long as I turn it off and the on again .

This happens even when the K3  is off . I have also tried disconnecting the k3s serial cable to the computer and even from the PS ,  but no luck. 

Wonder if any one has experienced such a problem.

Any ideas?

Thank you
Jorge HK4CZE