[Elecraft] K3S interface problem with KPA500/KAT500

[Terry Conboy]

I bought the 500 pair last fall and connected them to my K3S (2017 vintage) with the official Elecraft cables (which I've checked for correct pin connections and no shorts).  All three units are at current software versions.  The issue I have is that if I change bands on the K3S, nothing happens with the tuner or amp.  However, when I change bands on the KPA500, the K3S follows as expected.

I have the internal tuner in the K3S (disabled when using the 500 pair).  I set the CONFIG: KAT3 for KAT500Y.

Of course, the tuner and amp detect the TX output and switch quickly, but I’d like to have the tuner follow the K3S for WSPR receive.

I’ve corresponded with the customer service crew at Elecraft, but no help so far.  Anyone have any ideas about Config settings or anything else to check?

Thanks,
Terry N6RY