Legally extending range of PMR446

Xaccers · 25-06-2007, 16:12

My understanding of the unlicenced PMR446 radios is that they have to have an incorporated antenna (ie non-removable) and transmit at no more than 0.5mW

Is there anyway to legally extend this via an amature radio license?
I'm goind to be using some Midland G7's which can be modded to run at 3W (which is useless if there's no way to do it legally, although it should double the range) this summer for a weekend over a large area down by the New Forrest.
I'm more after increasing the recieve side rather than transmit (don't want to be blocking anyone out with a stronger signal if possible) to be able to contact base camp, or be contacted by base camp incase of emergencies (such as the kitchen tent being blown away again).
Now the G7 has enough space inside to fit a BNC socket, so longer antenna can be fitted, however, to just go ahead and do that would be illegal (as with the power mod, or even using the handset's LPD band).

So is there a license you can get which would make such modifications legal?

AntiSilence · 25-06-2007, 16:44

Quote:

Originally Posted by Xaccers

My understanding of the unlicenced PMR446 radios is that they have to have an incorporated antenna (ie non-removable) and transmit at no more than 0.5mW

It's 0.5W (which is 500mW).

I don't think there's any legal way to increase the output power, but you can have a look at http://www.446user.co.uk/ and see if they have any info.

446MHz is line-of-sight so the clearer the area the more range you can get. If you're in a very clear area, you can get several kilometres range easily, even with only 500mW.

**Graham M** · 25-06-2007, 16:50

Even if you did increase the transmit power you'd actually have to get caught to get in trouble.

AntiSilence · 25-06-2007, 17:15

Quote:

Originally Posted by Zeph

Even if you did increase the transmit power you'd actually have to get caught to get in trouble.

Yeah, there is that lol. Same as using CB's if you didn't have a license. Not bad now since they made CB license-free in December

Uncle Peter · 25-06-2007, 18:26

There is no amateur allocation in this part of the spectrum (446 - 446.1MHz) so unfortunately you cannot legally cover use of any such modified equipment under an amateur radio licence.

fireman328 · 25-06-2007, 19:17

As it is for emergencies only, is there no mobile phone coverage in the area which would suffice ?

rogermevans · 25-06-2007, 19:55

what are you planning to use it for exactly

Jon T · 25-06-2007, 20:31

Quote:

Originally Posted by Xaccers

Is there anyway to legally extend this via an amature radio license?

As has been said before PMR446 isn't an Amateur allocation.

Also, even if you did use Amateur Radio frequencies, then everybody with a radio would need an Amateur License(not really a problem, a trained chimp could pass the foundation exam).

Mr Angry · 25-06-2007, 21:57

TOP TIP!!

Several dozen of these and two empty tins will not only keep you on the right side of the fuzz - but will also enable you to find your way back to wherever you started out from!!

Uncle Peter · 25-06-2007, 22:10

Quote:

Originally Posted by AntiSilence

Yeah, there is that lol. Same as using CB's if you didn't have a license. Not bad now since they made CB license-free in December

Yep, probably better off getting hold of some cheapo handheld CBs from fleabay. As long as the additional bulk of the unit isn't a problem 27MHz is more suitable for this type of situation as the signal at these wavelengths is less susceptible to attenuation effects caused by solid objects like trees and walls.

AntiSilence · 25-06-2007, 22:19

Quote:

Originally Posted by Uncle Peter

Yep, probably better off getting hold of some cheapo handheld CBs from fleabay. As long as the additional bulk of the unit isn't a problem 27MHz is more suitable for this type of situation as the signal at these wavelengths is less susceptible to attenuation effects caused by solid objects like trees and walls.

Especially wet trees... They absorb radio waves like they're going out of fashion! lol. And with CB's, you can have upto a full 4W of output power (usually around 2-3W on 12V batteries though, but still ample).

Xaccers · 26-06-2007, 07:21

Quote:

Originally Posted by rogermevans

what are you planning to use it for exactly

There's a massive airsoft event over the August bank holiday down near Verwood by the New Forrest.
The terrain is quite undulating with different types of foliage, and there's going to be approx 1000 people this year (last year there were approx 650).
A gust of wind caught the kitchen tent and sent it flying.
My gf was back at the camp, and radioed for help. Both on G7's, mine was the only one to pick her up, while everyone else's radios weren't good enough.
I don't really want to interfere with other users by cranking up my power, so I was wondering if replacing the antenna's would do the trick, so they can pick up the weak signal at further range.

CB's not an option because it would require kitting everyone from our site (maybe 50 players) with rigs.
Mobiles aren't because of the lack of signal cover, and the risk of damage.

altis · 26-06-2007, 07:44

I'm sure it would be legal to kit out the base station with a high-gain aerial on a tall pole and then reduce the transmit power accordingly. The high gain and high location will benefit the receive path and the high location will benefit the transmit path.

You're bound to find something useful here:
http://www.geocities.com/euro446/models.html

Edit:
The aerial is supposed to be integral with the unit:
http://www.446user.co.uk/forum_topic_3579.html
http://www.ofcom.org.uk/radiocomms/i...raftir2009.pdf
http://www.ofcom.org.uk/static/archi...pdf/ir2009.pdf

Xaccers · 26-06-2007, 08:39

Stretching the term "integral" is possible, in that there is a PMR available with a coax leading to a roof mounted antenna, for use while in a car.
As the antenna can't be removed, then it's considered integral.

Uncle Peter · 26-06-2007, 10:04

Quote:

Originally Posted by altis

I'm sure it would be legal to kit out the base station with a high-gain aerial on a tall pole and then reduce the transmit power accordingly. The high gain and high location will benefit the receive path and the high location will benefit the transmit path.

Unfortunately this would still contravene the WTA and there is a question mark around the practicality of modifying one of these sets to accept a suitable connector (such as an N type) to connect the correct type of feeder for low power use at these frequencies. Feeder loss is a big factor at UHF frequencies.