My BMW R1150 GSAA at Deals' Gap

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Entries in transmit audio (2)


The Comms Box - Catching Waaaaay Up

Wow, it's already mid-August and I failed big time in documenting my efforts from much earlier in the year when I built the comms box for the KLX250S. I won't go into great detail on the construction steps in this posting, but following the mounting of the Pelican case to the rear rack, I

  1. Completed wiring up the radio, intercom and power distribution inside the case
  2. Completed connecting everything up wiring and wiring it to the bike
  3. Was hugely disappointed about the amount of alternator noise on the radio's transmit and receive audio(!)

Here are some pictures showing the construction efforts that went into the comms box.

Autocom and Yaesu radio mounted

Underside wiring - What you don't see

Where the wires will come out

Looks pretty clean

NMO-style antenna mount

Modified commercial PTT switch for the radio

I'd previously tamed some alternator noise on the GS by adding a 20 Amp DC Line Noise Filter from PowerWerx, so I ordered one up for this application and tried it out. It DID tame the noise on the receive audio through the intercom, but it didn't help at all on the noise that impacted the clarity of my transmit audio. So, after a brief period of head-scratching, I decided that I was simply asking too much of the little KLX250S's electrical system. I decided to go "off the grid" and go to a solar-charged, battery-only electrical system for the comms box.

Out came the DC relay that I'd use to switch electrical goodies on and off with the bike's ignition. That in itself didn't free up enough room for a battery inside the Pelican case, so I created a bracket to secure the battery to the top of the case. The battery is a 12 Volt, 5.1 Amp-Hr. sealed unit purchased from Batteries Plus

An Instapark All Black 5 Watt Mono-Crystalline Solar Panel was ordered up from Amazon. After a protection diode (1N5817) was added to the panel, a pair of aluminum brackets were fabricated to mount the panel above the battery and to the top of the case.

Simple brackets holding the solar panel and battery

Wiring details - no place to hide!

Another view of the 5 Watt solar panel

The Garmin and Yaesu head unit up front!

With everything mounted securely and wired, I'm able to say that the "off-the-grid" solution works as expected, with no electrical interference from the KLX250S. I decent sun, the solar panel extends the use of the radio, GPS and intercom well past the typical day of riding. An auxiliary power connector makes it simple to plug in for an overnight boost charge, too.


ICOM IC-F21GM Transmit Audio - How to speak and be heard

While recently riding in the mountains of North Carolina with a small group of GMRS radio equipped riders, one of the riders commented that my audio was a lot "lower" than that of fellow rider Ed Gray. Ed has the exact same Autocom intercom (Active 7 Smart) and GMRS radio (IC-F21GM). This got me thinking again. I hate it when that happens.

I was already "eating" the microphone in my helmet, so that didn't seem to point to the low audio problem and I know from Elizabeth's POV that she hears me loud and clear from the pillion. The Autocom doesn't have any user-adjustable controls for transmit audio, nor does the ICOM radio. However, I did begin to wonder about the FM Mode selection button on the radio. By default, these radios are all supposed to be set to FM Narrow, which takes up less radio spectrum every time you transmit. FM Wide is also an option and effectively adds a bit of punch to your signal.

Pressing and holding the Wide/Narrow button ensures that radio is in FM Narrow mode. I felt pretty certain that I was going by the book and using Narrow, so I tried a little test.

With the radio removed from the bike, rubber antenna and battery installed, I enlisted the help of a scanning receiver and headphones so that I could listen to myself when transmitting.

With the radio in FM Narrow mode, I was able to hear myself, but the audio lacked life. I pressed the Wide/Narrow button once (didn't hold it) which changes the mode to FM Wide. I repeated the test, but oh what a difference. The audio was substantially louder and easier to copy.

I'm going to leave my radio in FM Wide mode for future rides and ask for some comparison to Ed's audio. If Ed's willing, I also intend to run a little test with his radio, comparing his transmit audio as it is right now (no button pressing) to what it sounds like after a single press of the Wide/Narrow button (without holding). I'm expecting no change in audio, which will confirm that he's been running his radio in FM Wide mode.

Then, I guess the next question is whether there's anything wrong from the FCC's POV in running these radios in wide mode. More later.