[Elecraft] KPA-1500 problem

[RVZ]

Hi Guys,
 My KPA-1500 is having an issue: with the internal ATU tuned "OFF" or in "ByPass" mode, when transmitting the KPA-1500's relays occassionally chatter like a machine gun while transmitting.  It sounds just like the relays do when the ATU is turned "ON" and it's tuning an antenna for minimum SWR.  Are there any KPA-1500 configuration settings that could cause this to occur even though the ATU is turned "OFF"?  Any ideas why this is happening? Thanks!  Dick- K9OM