This ones been modified into one that works with a transceiver. Its the original model and unless modified as such it wont work with a transceiver. The Mark 2 and up will.
GSB 201 - rule #1, DONT EVER CHANGE THE BANDSWITCH WITHOUT TURNING THE POWER TOTALLY OFF. If you change the position while the amp is keyed you will
probably for sure burn up the bandswitch. The one I got given only works on 75 and 40. Someone burned the crap out of the switch - wont work on 20 15, or 10. The contacts are burned away.
I have a copy of the manual that covers every model made in a pdf file. - give me ur email and I'll send it to you. My bias leads are not hooked up inside the amp as sock -but there's no jumper. You need the manual. Me send.