[Elecraft] KPA500 clicking

[Wes (N7WS)]

I'm a relatively new owner of a KPA500.  I'm also, thanks to the new K3 
firmware, using QSK for the first time in my ham career.

These two facts have led to me hearing a slight clicking noise emanating from 
the amp that follows the keying. This is unrelated to drive or output power, 
since it happens in the TX Test mode too.  I understand that PIN diodes are used 
for RF switching but it still sounds like a reed relay to me.

Any explanation?  (Hint) Having a schematic would probably make this self 
explanatory.

Wes  N7WS