Headset Mod

I’ve been window shopping for single-sided headsets for portable operating, but at £80-120 I thought of how I might make my own. I purchased a cheap headset, a copy of a military style designed to be worn under helmets, marketed for airsoft enthusiasts. It has the advantage of being cheap (about £20 including PTT adapter), lightweight, and packs up small, but needs modifying to connect to a Yaesu radio, and the microphone is found wanting.

The headset is a modified “Z-Tactical Bowman Elite II”

I had previously toyed with the idea of modifying a spare MH-31 handset by adding an electret microphone element (I might still do this), so I had a few Panasonic WM-53B capsules (these cost a few pounds each), although I imagine many cheap electret capsules are appropriate. I started by hacking open the boom and replacing the stock element with the WM-53B electret. If you are trying this mod, be sure to make a note of the polarity of of the connectors on the boom arm, as you’ll need this information when wiring it in later.

Wiring diagram for the Panasonic WM-53B

Then I opened up the PTT enclosure. This helpfully has plenty of room inside, so I removed the existing cable (designed for a Baofeng HT) and fitted a chopped up network cable RJ45 and a chopped up 3.5 mm mini-jack. I also added a 3.5 mm mini-jack socket to connect an iambic key. I connected this to the “up” and “down” keys and these can be used for CW work, although the limitations of the FT-817 means it’s actually inferior to connecting to the dedicated socket in the rear of the transceiver. I also connected the PTT using the existing button, and directly connected the microphone output to the 8 ohm transducer for the speaker.

Wiring diagram for the PTT box. You can swap the 47 nF capacitor for something larger (1 μF?) for better fidelity. Given the problems with using the UP/DOWN keyts for CW, you may wish to leave that part out completely

I then moved on to the wiring for the microphone. Usefully there is a spare 5 volt supply from the Yaesu transceiver via the RJ45 socket; with the addition of a resistor to drop this voltage it can be used to supply the electret microphone element. A DC blocking capacitor is added across the microphone elements, and optionally a capacitor can be added on the output signal to act as a high-pass filter to optimise the audio. I’ve put a large capacitor to create a thin, punchy sound optimised for SSB, but in the future I might add a switch so I can bypass this to prioritise fidelity for FM work. I need to do some work to optimise the microphone gain (and speech processor in the FT-867D), so I’ve got a dummy load in the post to help with this.

The finished product, showing the PTT (black circular button), microphone connection (white wire, terminates in RJ45 plug), headphone connection (3.5 mm jack), iambic key connection (3.5 mm socket), headset and headband. Note the U-174 (“Helicopter” or “NATO”) inline plug and socket (U-92A/U) on the headset.