|Finished Portable Ear bud-Mic|
Following up on the "no-weight microphone" post (below) is an adaptation of two pin speaker mics often included with VHF HT's and readily available inexpensively on-line. These mics have the advantage of a PTT (push to talk) button. Shown above is an ear bud/mic that was included with a Pofung HT. I chose to modify this because the Elecraft headphone jack has low output and I didn't want to hold a speaker mic to my ear during reception. However, this adaptation will work for with a Kenwood style speaker mic, as well as with the ear bud mic shown above.
- glue gun
- one 3.5mm stereo to 3.5mm stereo 1 meter cable
- perf board
- ear/mic or speaker mic
- heat shrink tubing
- Cut the stereo cable in half. Strip the ends and determine the color coding to the tip, ring, and sleeve of the plugs.
- Cut the two pin connector from the ear bud mic. Leave 3 inches of cable with the plug. Strip the cable and determine the color coding for the tip, ring, and sleeve of each plug. These wires are tiny and cloth type, so put a dab of hot solder on the ends to make them conductive.
- Solder the wires from the ear mic in a row on the perf board and then match up the appropriate wires from the stereo cables in the adjacent row and solder them. Bridge the lands between the stereo cables and the ear mic with solder. Note that the speaker ground (sleeve on the small plug) will have two connections and that not all wires will have a connection.
- Test the assembly with you radio.
- When it tests OK, use hot glue to affix the cables to the perf board, wihich provides strain relief.
- Slide a piece of heat shrink tubing over the perf board and shrink it to provide protection.
- Adjust the mic gain and compression on the radio to match the mic characteristics.
- Note: because ground is provided by the speaker plug, both mic and spkr must be plugged into the KX for this to work. If you want to use the KX speaker instead of the earbud,you must put the unused earbud plug into the aux jack of the KX to provide ground in order for the circuit to function.
Hot glue for strain relief Wiring diagram for two prong speaker mic to Elecraft