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  1. #1
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    PTT Switch For Radio

    I have a set of PMR446 (license free, two-way) radios that I use for talking to my partner when out riding. We have ear pieces with microphones and put the radios in VOX mode so we can use them hands free. The problem is that in windy conditions or in traffic the VOX isn't that reliable and so my plan is to put a button or switch on the handlebars as a PTT (push-to-talk) switch.

    I know how to wire up the radio to the switch OK - my problem is finding an easy way to mount a small button or switch on the handlebars. I was hoping people could give me some advice - has anyone else done this? Are there commercial solutions? Photos of home made solutions?

    I've seen switches for motorbikes on the web but my impression is they were all quite large (and I don't have much room on my handlebars).

    Thanks,

    Andrew

  2. #2
    You need a new bike supcom's Avatar
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    A cheap and ugly aproach would be to get a pushbutton switch from an electronics supplier and epoxy it to an old headlight handlebar mount.

    Be sure to get a waterproof switch.

  3. #3
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    I've finally found a commercial solution that will hopefully be more robust than something I have glued together: http://www.intaride.com/ptt_options_...intercoms.html

    A bit more pricey however.

    I ordered the cheapest waterproof one. It hasn't arrived yet but I'll follow up when I've tried it out in case anyone else wants to give it a try.

  4. #4
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    I wish that I could find a microswitch that fits into the switch recess on the STI shifters that is used by the flightdeck interface...that would be a natural for radio or turning on your lights or whatever.

  5. #5
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    I have been meaning to take photos (and I will eventually if someone says they are interested) but I gave my PTT design a try on our recent (short) tour of Normandy.

    I used the buttons from intaride (as mentioned in previous post) attached ot the handlebars via the provided cable tie. I ran some wire (two lengths joined side-by-side to make a figure-8 - not sure the proper name for this sort of cable - i'll call it paired wire from here on) along the top tube (held on by string on my bike as my cable ties weren't long enough) with a 3.5mm mono plug on one end and a 4 pin mini-DIN plug on the other. I had to cut away some of the plastic on the DIN socket coming from the switch to get the DIN plug to fit securely.

    I was using Corba MicroTalk MT700 radios http://www.maplin.co.uk/Module.aspx?...ce=14&doy=24m4 from Maplin. The headsets were Alan 456s http://www.maplin.co.uk/module.aspx?...29243&doy=24m4 also from Maplin. When the headsets were connected directly to the radios and the switch on the headsets was in the VOX position the radios would transmit continuosly (good thing I didn't want to use VOX and so much for the Maplin website saying they were compatible).

    I wired a 2.5mm mono plug on the end of a short piece of paired wire and a 2.5mm mono socket on the other end. I split the pair in the middle (so it was 2 separate wires) and cut one of the wires. I soldered the free ends of the cut wire to the terminals of a 3.5mm mono inline socket. If you followed that description then basically you have a short 2.5mm mono extension cable but one of the pairs is broken by a 3.5mm mono socket.

    I soldered a 3.5mm mono socket and a 3.5mm mono plug to another length of paired wire (so it was a straight extension lead) making it the same length as the 2.5mm one described in the previous paragraph.

    The headset plugged into the 2 extension leads. The 3.5mm plug from the switch plugged into the 3.5mm socket on the microphone extension lead (the one with the 2.5mm connectors). The plugs on the 2 extension leads go into the radio.

    Amazingly it all worked. The radios were kept in small bags with velcro straps designed for connecting to a belt. I velcroed them instead to the bike racks.

    Problems to fix for next time:

    • On our one day of heavy rain my radio stopped working. Looked like the batteries were flat but changing them didn't help. The radio came back to life the next day. I guess it just got wet. The Maplin site claims the radios are water resistant but I guess thats a relative term! Next time I'm going to try wrapping the radios in glad wrap (cling film) to make them a bit more water resistant while still being able to see the screen and operate the buttons.
    • My partner always seemed to manage to get tangled up in her headset cable. I think the only solution for her will be bluetooth so I'll have to see if I can get or build a self contained bluetooth module. Anyone had any experience using a mobile bluetooth headset while on a bike or in the wind?

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