The Mighty Koss SB40 Headset with dynamic mic
Yaesu radios expect a dynamic microphone input. Condenser microphones require power to operate (often called phantom power). I have been using the Koss SB40 for about 2 years now. First with my Yaesu FT-891 and exclusively for the last 5 months with a Yaesu FTdx10. The sound and build quality is amazing and the price is spectacular. I often use it on the 3905CCN QSL nets for hours at a time, switching from band net to band net, and I always get great audio reports and comments on my audio quality. It is comfortable and remains comfortable. Finally, at a cost of $30 new, it is a no-brainer!!
To connect the Koss headset for Yaesu operations requires a microphone adapter cable.
DIY Microphone adapter cable (blue) for the Yaesu FTdx10(top radio). The adapter cable plugs into the FTdx10 via RJ45 8-pin plug and brings out the microphone audio to a 3.5mm female mono audio socket and out to a 1/4" female mono audio socket for PTT via a foot switch.
Many radios now sold by Yaesu use an 8-pin RJ45 plug-in module. Below is microphone wiring schematic for the FTdx10. While different Yaesu mics and rigs may have different features, wires number 4 - 7 are standard for Yaesu mic audio and PTT operations. Microphone adapter cables can be readily purchased, such as the INRAD M-YM adapter which lists for $14.95. While I purchased an INRAD adapter, I needed another microphone adapter and easily made for one only a few dollars.
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| Yaesu 8-pin RJ-45 wiring |
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| CAT-5e RJ-45 cable connector. Pin wiring order is #1 from bottom to #8 top (blk wire). In the plug above, wire #4 MIC GND corresponds to the blue wire, #5 MIC is the white/blue wire above the blue, wire #6 PPT is the green wire, and #7 GND is the white/black wire. |
Below is an image of an adapter cable being fabricated for an old CAT-5e cable, a 3.5mm female mono audio extension cable ($3) and a 1/4" female mono audio socket ($0.50). The wiring schematic above shows the 8-pin wiring as viewed looking at the Yaesu RJ45 socket. When viewing the plug of the CAT-5e cable, wire ordering goes from #1 and bottom increasing to wire #8 at the top. The above RJ-45 plug is of the CAT-5e cable. Wire to pin ordering was verified using a DVM testing continuity from the RJ-45 pin to the individual color coded exposed wires from (cable with end cut off). Pin wiring order is #1 (white/orange) from bottom to #8 at the top (black wire). In the plug above, wire #4 MIC GND corresponded to the blue wire, #5 MIC was a white/blue wire above the blue, wire #6 PPT was the green wire, and #7 GND was a white/black wire.
The microphone adapter cable plugs into the Yaesu via RJ-45 8-pin plug and brings out the microphone audio to a 3.5mm female mono audio socket (CAT-5e wires #4 & #5) and out to a 1/4" female mono audio socket (CAT-5e wires #6 & #7) for PTT via a foot switch. In addition to the FTdx10, the adapter cable has been used on an FT-891.
PPT foot switches can be purchased for about $50 or more. A DIY PPT foot switch was made using a 6ft 1/4” to 1/4” Audio Cable ($6 eBay) and momentary foot switch ($3 AliExpress). See image below. The exact same foot switch is sold by Adafruit product ID 423 ( & DigiKey 1528-1137-ND) for $7.50 plus shipping. One could get a switch much quicker, paying the few dollars more, from Adafruit/Digikey, as apposed to AliExpress’ 2 month slow boat from China shipping.
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| Fabrication of a Yaesu microphone adapter cable. |
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| DIY Yaesu microphone adapter cable with PPT socket. |
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| PPT foot switch made from a 1/4" audio cable and a momentary switch. |
FT-891 Tip: Use 1ft CAT6 patch cable and F/F RJ-45 coupler which can be cheaply purchased from from a vendor like Monoprice.com. Remove the FT-891 control head, unplug the Yaesu microphone, plug the patch cable & F/F coupler, and then replace the control head. Now you have access to RJ-45 connection without needing to remove the control head. This allows for switching between the regular hand mic and the a headset.
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| The INRAD M-YM audio adapter. |
