Bike to Bike - Cobra

[Cabby]

Hello everyone...I've just ordered these. Cobra MT800's

http://cgi.ebay.co.uk/SEALEDBrand-Ne...QQcmdZViewItem

These come with a basic headset ..earbud?......will this be OK on the bike for now or shall I look for a proper bike headset (advice).....I'm running out of time (and funds) for the National.

Thanks Kevin

[severs]

...a basic headset ..earbud?......will this be OK on the bike for now or shall I look for a proper bike headset

Headsets are the most painful part of bike comms. The "walkman style" earbud might be a bit of a laugh keeping in your ear while you don the helmet, and if it falls out due to cable-pull when you move your head, you can't put it back in.
A hook-over-ear type works better. The alternative is one fixed to the interior of the helmet, which is the "normal" cosnfiguration.

The microphone is the achilles heel. One that isn't designed for helmet use will pick up wind noise and drive you (or the person listening) crazy when you are riding at speed.

For this reason, good noise-cancelling helmet mic/speaker combos that are also reliable and have plugs/socket that are secure are expensive or rare. And when you take your lid off, they are no use.

I have recently been experimenting with a range of throat-mic sets with my home made intercom and Motorola PMRs. The pro or military type which is a fabric band around the neck with a curly sound-tube to your ear (with ear hook) seem to work best. Wind noise is irrelevant and the setup is the same whether you wear your helmet or not.
Cheaper imitations (I've borrowed three) are OK too, but you get what you pay for. You may have to chop the connector about a bit or make an adaptor - take care with this because low-cost plugs and sockets wobble and make deafening "clicky crunchy" sound effects that will drive you crackers.

[Cabby]

Thanks Severs, I've ordered one of the throat ones.....Just hope it gets here in time

[Lumiya]

Severs has already said everything I was going to say about the Microphone/earpieces.

Just out of interest what power are these? They say they're UK legal so that should be half of a watt. If so then don't expect the 5km range (not unless you're sat on a hill talking to someone on another hill 5kms away) More likely round town/forests/hilly terrain you'll get about half a mile with comms getting steadily worse with anything over a kilometer or more which will also be very dependant on where you mount them.

Kymmy

[Cabby]

Severs has already said everything I was going to say about the Microphone/earpieces.

Just out of interest what power are these? They say they're UK legal so that should be half of a watt. If so then don't expect the 5km range (not unless you're sat on a hill talking to someone on another hill 5kms away) More likely round town/forests/hilly terrain you'll get about half a mile with comms getting steadily worse with anything over a kilometer or more which will also be very dependant on where you mount them.

Kymmy

Thanks Kymmy.....500mW...That is 1/2 a watt I think , I haven't got them yet but they do describe them as "terrain dependant" so you'll be right....I reckon I'll try them in the breast pocket of my jacket.

Hopefully the throat mike will help.

[Lumiya]

Hopefully the throat mike will help.

No doubt about it...Even expensive noise cancelling microphones don't compare to a throat mike also throat mikes are the only mike that won't trip the VOX until you have something to say.

And yes 500mw = 1/2 watt

Kymmy

[severs]

Except for when you cough. Or burp.

There are a number of "hacks" on the net for extracting a bit more than 500mW from many PMR handy talkies, this is absolutely illegal and therefore, your honour, I'm not recommending you use any of them or modify the set in any way, officer.

But when you do modify them, an external antenna of tuned length is much more useful than extra power, and aids reception as well as transmission. It works best with a "fixed" on-bike setup though, so walking around the petrol station / bike rally / GP with set in pocket and mic strap around neck becomes useless. Otherwise, try substituting the rubber blobby antenna with a straight "whip" of about 16-17cm length as a stopgap. That will improve things slightly.

Don't crank up the output power very much or you'll fry the final stage which is not designed to dissipate a lot of heat.

[Cabby]

Thanks Severs...Noted !!

Hope they arrive before Thursday.....

[Lumiya]

Otherwise, try substituting the rubber blobby antenna with a straight "whip" of about 16-17cm length as a stopgap. That will improve things slightly.

Just out of interest why 16-17cm's in length?

Kymmy

[Cie]

....because ~16cm is a quarter wave at 446 MHz ?