External Mixer board for Heathkit SB-620?
 

Does anyone sell an external mixer board for
the SB-620 Panadapter? One of our members
is sure he saw it announced or advertised in QST, but
we can't locate it. He is aware of the web pages detailing
how to change the components for different IFs, but
doesn't want to hack up a working panadapter.

Zack Lau W1VT