Mini PTT Mic for FX-4CR

A simple mini ptt mic for fx-4cr radio. Lightweight. Good for POTA/SOTA.

1× Electret Condenser Microphone Capsule (ECM)— PUI Audio AOM-5024L-HD-R (DigiKey: 668-AOM-5024L-HD-R-ND) or Primo EM272J (DigiKey: 5956-EM272J-ND)

1× Resistor 2.2kΩ 1/4W — YAGEO CFR-25JB-52-2K2 (DigiKey: 2.2KQBK-ND)

1× 3.5mm Stereo TRS Jack PCB Mount — Same Sky SJ1-3515N (DigiKey: CP1-3515N-ND)

1× Tactile Switch SPST-NO Momentary — CIT CT11027.0F100 (DigiKey: 2449-CT11027.0F100-ND)

2x M2x10 machine screw + nuts

Hookup wire 24/26awg

1. Print the parts
2. Snip the legs 4 & 5 (see datasheet) of TRS Jack
3. Snip legs on one side of the momentary switch
4. Place parts inside the enclosure, get measurements and roughly cut and strip wire
5. Solder wire to mic capsule pads, take care to NOT get the capsule too hot. Datasheet recommend to keep it on metal surface to dissipate heat while soldering
6. Solder parts as per picture, do it outside the enclosure
7. First, insert the TRS jack, then switch
8. Press the nuts to switch brace feature, slide in the switch brace, and add screw to hold switch in place
9. Insert the ECM in to its hole. (I added a small piece of cotton cloth to act as wind guard and to make ECM fit snug, didnt want to glue it)
10. Once all parts are in enclosure add the cover, small dab of super glue will seal it. (i added a small piece of foam to fill the inside of the enclosure to prevent anything from rattling before sealing)
11. Press fit sound cone, glue it in place if you want.