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.
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.
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.
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.