Use your 4 Pin Cobra Microphone on a 6 Pin Delta Force Radio with this adapter
I did test on a President Lincoln 2+ with an Astatic 878DM desk microphone and no issues were found when using this adapter cable. No channel changing was present while transmitting on a Lincoln 2+ radio.
 Can't guarantee it will work on all President 6-Pin radios with different style of non-Astatic microphones. Make sure your microphone is wired for the standard Cobra 4-Pin style.
Tested on a CRT SS9900 radio and found it to be working correctly with an Astatic 878DM desk microphone. No issues were found with channel changing while transmitting using this adapter with the Astatic Microphone. 
Can't guarantee this adapter will work with all microphones with the CRT SS9900/AT6666 radio. Make sure your microphone is wired for the standard Cobra 4-Pin style.