After putting this off for a number of years, I finally decided to build 
a box to give me more PF keys for the 590.  Turns out I had all I needed 
right here.   It's not completely complete yet, since I have to drill 
holes for switches, but it has  been  wired up temporary and seems to work.

Main component is an old MFJ TNC to radio interface.    The KAM is long 
gone and I clipped the 13 pin DIN off it some time ago, but it has an 8 
pin round mic jack on the front and  8 wire mic cable  with plug coming 
in the rear.

Also had the needed switches and other odds and ends  laying around.
One thing I learned is that the 590 will let you change the UP/DOWN 
buttons into additional PF keys,  so I will wind up with 6 pf keys on 
the box and the original 2 on the radio.

Anyone using a microphone with UP/DOWN buttons can reassign them as PF 
keys if you don't need the UP/DOWN function.

Also added an RCA jack for PTT, and a 1/8 jack for mic input, since the 
mics I use  all the time have  1/8 plugs.   Maybe later I'll add  a mic 
input for  a condenser mic, using the 8 vdc found  on pin 5 of the  8 
pin cable.


73, Steve KW3A