Last month I wrote about my “new” VTX 1800. At that time I was just trying to do the minimum to be able to support the MS-150 coming up later in the month. To that end I just ran power and antenna to the front of the bike and mounted my old FT-90 (what’a trooper!) on the handlebars and ran a speaker wire to my helmet or a separate headset. I did all that and was ready to go. However…
Having gotten that far, I wondered if I could do the actual integration into the helmet? The FT-90 was the very first radio I had mounted on a Goldwing, so I figured I still had notes and drawings. When I looked them up, however, I found I had used the Kennedy electronics to make it all work. Ok fine, I said, I’ve mounted other Yaesu radios without the Kennedy stuff, surely I can do that again?
When setting up a Yaesu radio to work with a helmet and external PTT, it requires some special wiring – generally from the mic jack. In particular you need to add some resistors to the circuit to get the PTT to work.
Over the years Yaesu has used two different resistor configurations. In the earlier radios (FT-90 and FT-8100) it was a 27k ohm resister. More recently (FTM-10 and FTM-350) it needs two 330k ohm resistors. So, I dug through my parts drawer and managed to come up with the 27k ohm I need. Cool!!!
So I set to work to get everything connected – Mic wires to the right Din plug pins, speaker connections, ground etc. I always forget with my drawings whether I’m looking at the contact side of the din plug or the solder side? Of the male or female plug? So, took my best shot and got it right the first time.
BTW – a little trick I use to verify the right pins – I put my helmet on and jumper the ground pin to one of the speaker pins (L or R) with a voltmeter set to tone when it has zero resistance (Continuity). When doing that, the meter puts out just enough voltage to make small scratchy sounds in the speakers. Works for me.
So, having put all the wiring together, I connected everything and it worked fine, as far as I could tell. In the shop I could hear the repeaters opening when I pushed the PTT. However, I couldn’t get anyone to reply, so I wasn’t sure if I was getting out or, if so, was intelligible…however…(there’s that “however” again…)
I got to thinking about my FTM-350 sitting on a shelf. I had used it before on my Goldwing and it worked wonderfully. It can actually work 4 bands at a time (sorta) and will ping APRS beacons on one of those if needed. But, it’s a little big and I wasn’t sure I wanted to risk damage by running on a motorcycle not as smooth as the Goldwing. So, I pulled out the head and mounted it temporarily to the bars, and that was it. I decided go for it with the 350.
I also looked at picking up a used FT-7800 or new FT-7900. Or even the digital FTM-100DR. But more on that later. Suffice to say – I decided to “make do”.
One of the reasons for using the FTM-350 was the APRS. I really wanted to have APRS, but with the FT-90 it would have to be an add-on. I had, in fact, set that up with the 90. I mounted a second antenna, put my VX-8 in a side pocket of my rear rack bag, and connected the antenna. Worked great. But, having this fancy, dancy FTM-350, I figured I’d try that instead.
So, back to the drawing boards on the wiring for the 350. Found my old drawings and notes and started to put together a harness for the 350 – with those 330k ohm resistors. But then I said “Oh wait…”, the 350 has built in Bluetooth! And I have a Sena Bluetooth helmet system. Gee, I wonder???
So, I worked at pairing the Sena to the 350 and, after a couple of tries got it connected. I then ran a test from my desk and got John (W5JFR) to reply. He indicated it was workable, but I just didn’t sound like myself. (don’t know who I did sound like, but…)
So, I then set about putting everything together on the bike. Basically I had to run a control cable from the rear where the body would be, to the front for the head (RJ-45 network cable – standard on the newer Yaesus, and I believe Kenwoods). And a separate speaker cable as a backup. With this setup, I’ll still have a hand mic mounted up by the head and a separate speaker connection. So, if the Bluetooth fails, I still have the old “manual” way to work.
Then came the antennas. That’s a story in it’s own right. I’ll save that for next month. And, as for the bike…well – that’s yet another story – stay tuned…
73’s and ride safe.