



Mic-E Connection to ICOM IC-W32A Hand-Held Transceiver
_______________________________________________

Description of problem:


	The ICOM IC-W32A uses a Push to Talk Switch in series with the
		microphone audio.

	Other ICOM HandiTalkies also use the same arrangement,as
	       allegedly does YAESU & RadioShack.

	The MIC-E design does not provide for this arrangement and
		several people have suggested work-arounds which do 
		not provide full functionality.


One Solution:

	My solution was to obtain an inexpensive second Speaker-Microphone, 
	a 4 conductor replacement microphone cable, 
	a 5 volt, 250 ohm SPST-NO Reed relay and a 1N4004 Diode.

	All parts can be obtained from your local RadioShack store:

	Microphone  -  Cat No. 19-310   Price approximately $20.00

	Reed Relay  -  Cat No. 275-232 Price less than $5.00 

	4-cond+shield Coil Cord  -  Cat No. 278-358  $2.99 
	
	The Diode was from my junk box but is also available from 
	Radio Shack.

How it works:
	This solution re-wires a microphone so as to bring out the 
	PTT switch on its own set of wires.  A reed relay is used to
	provide the normal serias PTT switch function on the output of 
	MIC-E.

	When the microphone PTT switch is depressed the reed relay is 
	energized and is kept energized by the MIC-E until the 
	transmission is complete.

	The contacts of the reed relay are connected in series with 
	the microphone audio going to the HT in the same manner that 
	the original PTT was connected.

	The entire relay assembly is mounted on a component carrier 
	with connectors to provide connection to +5VDC and the 
	Radio PTT signal.  In this manner it is simple to unplug the
	relay assembly and substitute a different header for use
	with a different radio.


Procedure:

	1)      Remove the screw(s) holding the microphone cover in place. 
		( Some have three screws, others only have one screw).

	2)      Carefully unsolder the cable from the microphone, making
		sure leave the resistor & Capacitors connected.  This cable 
		will be used to connect the MIC-E to the HT when you are done.

	3)      Check the fit of the new cable in the mic housing, you may
		need to put the housing back together and slightly ream the 
		cable hole, carefully with a drill, to fit the new cable. 

	4)      Remove any remaining wires from the PTT switch.


Connecting the new coil-cord to the microphone:

	  Note - be sure and keep track of the wire colors used for each 
		 connection.

	1)      Connect the shielded wire, in the new cable, to the hot side
		of the microphone.

	2)      Connect the shield braid to the opposite side of the
		microphone as well as the return side of the speaker.

	3)      Connect one of the remaining wires to the other side of the
		speaker.

	4)      The two remaining wires connect, one each side, to the PTT
		switch.

	5)      Replace the cover on the Microphone.


Wiring the 8-pin Female Mike Connector:

	To make jumpering the personality header easy I used the following 
	connections.

	Pin #                    Function

	   2                    PTT Ground

	   3                    Microphone PTT

	   4                    Speaker ( RXA)

	   5                    Microphone Audio

	   6                    Microphone Ground (Shield braid)


Header Jumpers:

	Using the above mentioned wiring to the 8 pin female mic
	connector, the header is wired as follows:  Note if 
	you did not use the above pin numbers your header 
	jumpers will be different.


	PIN  jumpered to PIN

	 2                15
	 3                14
	 4                13
	 5                12 + One Reed Relay contact
	 6                11
	 8                --   Remaining Reed Relay contact

	Note that these jumpers are straight across the header and that
	PIN 5 & 12 also connect to one side of the Reed relay's contacts
	ant that the other side of the Reed Relay's contacts connects to
	Pin 8 on the header.


Connection of the Reed Relay.

	1)      Connect one end of a short piece of hookup wire to PIN 5 on
		the header.

	2)      Using a second piece of hookup wire connect one end to Pin
		8 of the Header.

	3)      This step describes my method of mounting the relay which
		allows for rapid reconfiguration if a different radio is 
		to be used with the MIC-E.

		I placed the Reed Relay on top of the header with the 
		terminals sticking up in the air and the coil terminal 
		end of the relay orientated towards the PIN-1 end of 
		the header and the other end flush with the PIN 16 
		end of the header.

		I then used a hot-melt glue gun to fasten the relay to 
		the top of the header, this makes the relay and header 
		an unpluggable assembly.

	4)      Cut and strip each of the two pieces of hook-up wire so 
		that they are proper length to solder to the contacts of 
		the reed relay and solder each of these wires to one of 
		the reed relay contact terminals.

	5)      Connect the 1N4004 diode directly across the relay coil
		terminals with the cathode end towards the front panel 
		with the header installed.

	6)      Connect one end of a piece of hookup wire to the relay
		terminal connected to the cathode of the 1N4004 diode.

	7)      Using a second piece of hook-up wire connect one end to 
		the relay terminal connected  to the anode of the 
		1N4004 diode.

	8)      The Anode end of the diode connects to any pin on 
		"JPR".  NO JUMPERS should be installed between pins 
		on "JPR" and pins on "JPC" while using this 
		configuration.  I used a .100 " center female connector 
		from an old computer for this connection so that it can 
		be unplugged. 

	9)      The Cathode end of the 1N4004 diode connects to +5 VDC. 
		again I used a  .100 inch spaced connector and soldered 
		pins in the JP3 connector  intended for an internal GPS.  
		If you are using an internal GPS you may need to pick up 
		the 5 volts from some other point, such as JP1-PIN 2.

	10)     Leave all the jumpers between JPL and
                JPC in place	

Connecting the MIC-E to the HT:

        1)      Solder splice the original Microphone
                cord to the RJ-45 cable provided with
                with the MIC-E.  Use heat shrink tubing
                over these splices and a larger diameter
                heat shrink tube over the outside of the
                splice area for additional protection.

One more useful Mod.
                You can mount a small toggle switch
                in the microphone housing with it's 
                contacts in series with the speaker.

		This allows you to turn off the 
                packet racket when using the MIC-E in 
                automatic mode. 
                 
		--------------- E N D   O F   D O C U M E N T --------- 
	
Updated: 20-Mar-1999	
Dan Welch - W6DFW
amersci@flash.net

