Bicycle mobile radio

[MattH]

(split out from this tread on racks as this is drifting well off topic)

Mine is going to be left on all year round(but then i plan to attach and antenna to it for a radio, i do amateur radio) and will be used all year round.

I did some experiments with this last year, trying out APRS. The bike and rack don't make a particularly good ground plane, and unless you have a very long antenna (making you look a bit silly) then your antenna doesn't have clearance above you which affects efficiency. The next thing to try here is something like an FBK attached to a fibreglass whip, but the main reason for me stopping the experiment is that I found that even with a good antenna system on my car 5W wasn't really enough to give consistent tracking in this area. 25W seems about optimal, but then I'm into the extra size and weight of a mobile radio and battery rather than a hand held and tracker stuffed into a side pocket of the saddle bag.

My idea was to either have a L shaped mount on the back, or have a metal plate ontop of the rack with a body mount on that and a 1/4 wave of 2m ontop of that.

I used an old Diamond K401 hatchback mount. It is possible to arrange it so that the channel that would normally go horizontally around the edge of the hatchback is actually vertical, then fasten it to the light mounting plate on the back of the rack - the light was still fitted just with the antenna mount between it and the rack.

I dont want a 1/2wave on, i really would look like a right twat with that on.

Agreed  In a bit of particularly twisted logic I was thinking that this was an excuse to get a recumbent, as the radio gear could go in a tail box and a 5/8 antenna would look like/could be used as a flag mast. And then I could add a neon bulb to the top of it so it would light up when the tracker is sending a position update (or I'm talking on it). Or maybe not.

But, the places where i ride i should be able to hit the local repeater with the handheld(ill be using the Jingtong) and be ok. I did have it mounted on a plate which was then attached to the seat rails but i just couldnt get the SWR down enough. Hoping the rack will make abit of difference.

You could experiment with a counterpoise - I ran one taped to the mudguard.
Bicycle Mobile Antennas - ARRL has some ideas, and there is more info at the BMHA - Bicycle Mobile Hams of America.

Got an idea of going into Derbyshire up a hill and seeing what contacts i can get.

I'm very tempted to do some SOTA activations this year, and am just collecting bits of pipe to knock up a portable antenna similar to the G3CWI's MFD. That should be very easy to transport by bike, only take a minute to erect, and be much more efficient than something bike mounted. Of course, it can't be used whilst riding along, but ignoring any safety aspects of operating whilst actually riding you'd then also have to figure out some microphone system that isn't overcome by wind noise.

I've used throat mics and bone conductivity mics that fit in your ear; they work but very sensitive to being positioned correctly and the audio quality doesn't compare to a good quality normal mic. I've also found that you have to do a self check on them, as sometimes you think they are positioned correctly but they are simply not working and need to be refitted.

[1gear]

Ive got an old hatchback mount aswell that i thought of using, but it doesnt angle.
Ive got a nice little 1/4 wave though. Its sprung at the bottom so if i knock it then it will just wobble, which i quite like.
The counterpoise might be something that i need to do. Ive got some welding rods that i guess would work fine, and allow me to bend. Would be easy to attach onto the earth side of the antenna aswell.
I wouldn't mind a recumbent. Nice big antenna on the back instead of a flag, radios in the back box.
Just had a search for the MFD antenna. Looks pretty good. I like how it can be either a vertical or horizontal. Might have to either look at how to make one, or just buy one. What pipe are you using for it?

For mic i was just going to use a normal fist mic. Im fine riding one handed, and if i need then i can just drop key and put both hands back on. Just got to find a way to mount it so i can easily put it down, without the risk of it dropping off.

[MattH]

Just had a search for the MFD antenna. Looks pretty good. I like how it can be either a vertical or horizontal. Might have to either look at how to make one

Dead easy, it's just a dipole - so two bits of wire about 19" long (assuming 2m use) soldered to the end of the coax, and wrap a few turns of the coax around the leg of the T sticking out as right angles to the dipole. You could use the centre of the coax as one leg, and a separate piece of wire connected to the braid as the other.
If you build it inside pipe with a removable t-piece to allow folding, then something like a piece of elastic attached to each end of the dipole and the end of the pipes would take out slack when assembled (like elasticated tent poles).
The FBK coax antenna is possibly simpler mechanically to run up the inside of a pole. Raynet use a version of this with a longer tail and a simple choke added (see bottom of this page)

, or just buy one. What pipe are you using for it?

Plastic water pipe - lots of fittings are available from DIY sheds.

Alternatively, you could do something with cheap fibreglass or plastic tent poles - the really cheap ones that use plastic couplers would be ideal. Maybe you'll have some at work from returned tents that are due to be skipped?

For mic i was just going to use a normal fist mic. Im fine riding one handed, and if i need then i can just drop key and put both hands back on. Just got to find a way to mount it so i can easily put it down, without the risk of it dropping off.

I'd be wary of doing that - I really don't like holding things that could get tangled or cause any delay in heading for the brakes. The only way I'd even vaguely consider a fist mic is if it came over a shoulder and was attached to my shoulder or neck (ideal use for a jacket with epaulettes). Then it could be dropped and would rest half way down my chest away from anything critical.
Ideally though, a headset and locking PTT (or one of the PTTs that you velcro to a finger with a cable running down your sleeve) are best from a safety point of view - that's what I always use in the car. Even as a penniless student oaf I built a low profile headset - an electret mic attached to the end of a bit of bent coathanger, with the cable heatshrunk up the boom part.
More recently I've knocked up a bluetooth adaptor so I can use a regular bluetooth headset with any of my radios - but that still has wind noise problems if used out walking, let alone whilst riding.


I'd be interested to know what the pro tour riders use as mics, it looks like maybe something just clipped to their collar.

[1gear]

Yeh, think they just use a mic attached to the collars of their jerseys. Don't think they mind too much about wind noise or anything.

I might give that dipole a go. Ive got enough cable just sat around and coax. I should have some pipe around somewhere aswell to put it in.
All the tents we have returned all have metal couplings, and dont think i could just nab one either. We dont have many returned, usually it will just be the pole to be sent away to be fixed. But i might have an old tent pole somewhere that i can use a pole from.
I used to have a good dipole made from coax on abit of plastic card type thing. It was great and would fold up small. But i got out of the hobby, cleared my room out and it went. Wish i didnt through it now, it worked really well.

I dont really mind using a fist mic. If i need to really brake hard i can just put my hand with the mic in back on the handlebars. I only have a brake on the front anyway with it being fixed.
Only 2m use at the moment. I wouldn't mind going hf portable but no radio capable of doing it. The Yaesu FT-897 isn't coming along! Bit too big for bicycle mobile.

[MattH]

All the tents we have returned all have metal couplings, and dont think i could just nab one either. We dont have many returned, usually it will just be the pole to be sent away to be fixed.

OK. Back when my wife used to manage an outdoor shop, there were certain product ranges that weren't returnable (typically the own brand stuff that was sourced cheap from China). If it came back faulty then unless it was a trivial fix it was binned when they got around to it. The staff could ask for any of it before it went to the skip - so taking this faulty stock was all above board and acceptable to the management.

[1gear]

All the tents we have returned all have metal couplings, and dont think i could just nab one either. We dont have many returned, usually it will just be the pole to be sent away to be fixed.

OK. Back when my wife used to manage an outdoor shop, there were certain product ranges that weren't returnable (typically the own brand stuff that was sourced cheap from China). If it came back faulty then unless it was a trivial fix it was binned when they got around to it. The staff could ask for any of it before it went to the skip - so taking this faulty stock was all above board and acceptable to the management.

I wish it was like that.
If it was id have a lovely Berghaus coat(with a zip problem that could have been fixed under the warrently!), berghaus gloves and some other stuff that just got thrown in the bin.
But it cant be wrote off, binned and we take it out. Or at least we didnt used to be able to.
So it was just put outside in a bag.
Unfortunately, the bin men would come and take it away before the end of the day, so no nabbing it!