AN INEXPENSIVE TNC/MIC SWITCH


FINDING IT AN INCONVENIENCE TO HAVE TO UNPLUG MY MICROPHONE CABLE FROM MY
RADIO TO CONNECT MY TNC CABLE AND VICE VERSA, I DECIDED TO LOOK FOR SOMETHING 
BETTER.  FINDING READY MADE SWITCHES COSTING ABOUT $40, I FIGURED I COULD
BUILD ONE CHEAPER.  THE 8 PIN FEMALE MIC CONNECTORS WERE EASY TO FIND AND 
THE 8 PIN MALE CHASSIS MOUNT MIC CONNECTORS WEREN'T BAD EITHER, BUT IT WAS 
ALMOST IMPOSSIBLE TO FIND AN 8 POLE 2 POSITION SWITCH.  WHILE LOOKING THRU
A COMPUTER EQUIPMENT CATALOG, I NOTICED THE FAMILIAR A/B DATA SWITCH.  
THIS WOULD WORK JUST FINE.  IT WAS ALREADY IN A METAL BOX (SHIELDED) AND
YOU COULD GET IT WITH RS232 9 PIN CONNECTORS.  MAKE SURE YOU SPECIFY 
METAL BOXES BECAUSE SOME COME IN PLASTIC.  DO SOME SHOPPING AROUND SINCE
DIFFERENT SUPPLIERS OF A/B SWITCHES CHARGE ANYWHERE FROM ABOUT $9 TO $30
FOR THE SAME TYPE OF SWITCH.  IF YOU ARE MAKING UP YOUR OWN CABLES, (REF-
ERRING TO THE MANUFACTURES SPECS FOR THE PROPER CONNECTIONS TO YOUR RADIO),
YOU MAY OPT TO USE THE RS232 CONNECTORS ON SOME OF THE CABLE ENDS GOING TO
THE A/B SWITCH INSTEAD OF THE MICROPHONE CONNECTORS (9 PIN RS232 
CONNECTORS ARE MUCH CHEAPER THAN THE 8 PIN MICROPHONE CONNECTORS PLUS 
THEY ARE ALREADY INSTALLED IN THE SWITCH BOX).  JUST USE YOUR IMAGINATION.
BUT REMEMBER THAT IF YOU CHANGE THE CONNECTORS ON THE A/B SWITCH,
PIN 1 IS PIN 1 ON ALL OF THE A/B SWITCH CONNECTORS, PIN 2 IS PIN 2, ETC.
PIN 9 WAS NOT USED ON MINE SO I USED IT FOR A GOOD GROUND ALONG WITH THE
SHIELD.  MY SWITCH WORKS FINE AND IT COST ME ABOUT $20.  THE SHACK ALSO 
LOOKS NEAT WITHOUT CABLES LAYING AROUND WAITING TO BE PLUGGED IN.  GOOD 
LUCK!    N4YMJ     CARROLL