The AM Forum

I have a stock DX-40 and a vintage unamplified D-104. The mic has Red, White, Black & Blue wires along with the shield. Can someone tell me the proper wiring to the old style center mic connector? I just want to get audio to the old Heathkit. Thanks!

The stand is marked UG8

Have you pulled the bottom plate off? ther's a skizmatic on them.......

klc

Someone who had this before me GLUED the bottom plate on so I have no access to the diagram.

IF the wiring has not changed from factory:

White would be the audio line.
Black and blue would go to the shield
Red goes to the PTT line.

To at least test this. Put your ohm meter from Red to Black and push the D104 bar. If should show on the meter. 

C

C Thanks so much. I appreciate it!

So what happens if you ever have to open it up to fix something?  That must be one strong brand of glue if you can't pry the cover loose and re-attach it using the normal screws. That has to be a CBification.  Hope they didn't commit another popular good-buddy modification and poke multiple holes in the diaphragm of the xtal element while they were at gluing the bottom cover on.

Disassemble the head and use a VOM to check continuity from each connection to your cable.   You can also then inspect the diaphragm for damage (induced or accidental) as Don indicated.

Dick,

Probably a good idea to pry off that plate.  I doubt the glue bonded the steel all that well.  The genius that glued on the bottom plate may have glued the amplified mic for all you know.  Glues typically can get broken down with solvents or heat.   Also, there is a real possibility the audio is out of phase.  Which Heath TX?

Peter

If the audio is out of phase, you can reverse the connections to the xtal element.  Unlike a lot of xtal elements, the stock D-104 does not have a defined polarity.  It's simply a bakelite case with two terminals.  Either one can be used as hot or ground. It can even be configured for balanced output.