The 150 needs 6 wires..im not 100% sure, but i don't think you can wire that mic to that radio.
some johnsons, and i believe the 250 is one of them, have a special way of switching from receive to transmit in which they actually switch a voltage from one circuit to another.
this requires more wires than you have in that mic.
some mics that are compatible with this radio are the CS-1, CS-3, +3B, and the expander 500.
if i remember correctly, you need to have a six wire mic to use with a johnson such as yours.
LC
Hello.. I got an early (ssb+2 shape) factory desk mic for my 250 Johnson and I'm having trouble getting it wired correctly. The mic wiring ive found online isnt working at all. The hand mic has 6 conductors and the desk mic has 4... Help???
I try to explain things clearly ..Hmm. Blazer191 was last seen August 2016. Doesn't look like he'll be likely to see your answer.
Pretty good explanation, though. The 5-pin plug uses the metal body of the plug and the lock ring to complete the sixth wire's circuit.
Back in the day, it would puzzle folks how a 6-wire cord connects to a 5-pin DIN plug. The metal body of the plug is the sixth "pin".
73
I tend to fat finger the keyboard should have read 250.. Not 150..I try to explain things clearly ..