[Elecraft] KPA500 RF output wiring

[Johnny Siu]

Hello Group,
 
The connection between the RF deck to the RF SO239 output is a pair of twisted wires instead of a coaxial jumper.  Is there any reason for such a design?
 
From reading of the manual, there is no mention of spurious emission and 3rd order distortion (two tone test).  Where can I find these information?
 
Thanks for your help in advance.

TNX & 73,


Johnny VR2XMC