Post by anon on Jan 31, 2007 8:16:09 GMT
Over the past 12 months we have noticed that the PMR radios that we are using on the club runs, have given a varriable range to there use.
On 1 run we were getting a clear transmitt and recieve over a mile range, but it`s also been down to just 20 foot.
So Chris and myself decided that we needed to find out why and herein is what we found out, with the help of a couple of friends and the internet.
The Cobra radios that most of us are using are in fact 2 way walky talkies and so are designed with that in mind. What we mean is that for them to work at there best they should be held in your hand near your mouth/ear. When in this position the arial will be vertical and that`s when it works best.
Now some riders keep there radio (like me) in there jacket pocket, others under there seat and others in there tank bag.
Now the problem here is that all 3 of the descibed ways will cut down on the range of the radios, especially if the radio is laid horizontal.
Most of us run the radios on rechargable batteries. This will also cut the effectivness of the radios as they are designed to run on 6 volts and the rechargable type batteries only put out 4.8 volts. Added to this they only put out there max power for around an hour. So as you can see these things also go against the radios working.
Now what would be an ideal answer to all of this isn`t so easy to impliment.
First the power is easy to deal with, by either using normal batteries or better still the bikes power after being dropped to the required 6 volts. We will be posting a simple to make and cheap way of doing this in the near future.
Second and this is were the law comes in. The law for these radios states that they cannot have a detachable aerial and must not excede a maximum output of 500mw. Now it is easy enough to get around the aerial problem by simply attaching and aerial to the bike and running a lead to the radio and sealing it in. When we tried this we got another 20 yards reception which for the trouble and cost was not worth the agro.
The effective range of the standard PMR is quoted on one source to be 400mts. Thats probably about right in real life usage, we have all suffered from a lack of transmitting range, it's well known that these units can receive for a longer distance than it can transmit. Making it quite hit and miss on many of the runs and less of an effective means of communication. I can think of several times when the back marker cannot communicate with the front marker. Which is a real pain at times, adding to the stress levels of all run organiser.
In practicality there are ways listed below that can help sort all of the problems out, or at least increase the effective range of these units. But the only real way to do it is to spend money on the pro-kit. To that end both myself (Reaper and Speighty581) are getting units that are capable of effective transmit and recieve ranges, and will let you know how well it works....also, where we attend runs, will make effective use of the system to keep both front and rear markers in communication.
So what do you need to do to maximise your enjoyment of the PMR radios.
1 - Keep the unit and therefore the aerial vertical and away from your body and the area of the bikes alternator (which produces a magnetic field). Try to get it as high as possible and don`t cover it in anyway. Another place not to mount the radio is inside the nose fairing, the frame. tank and your body absorbs most of the signal. If you keep it on you, have it on the outside of the body, belt clip is ideal...in the underarm area.
Keeping it vertical is very imporant, the orientation of the signal is quite important. Otherwise your again reducing the effective range of the unit.
2 - Run the radio on batteries that add upto the recomended voltage. Better still convert it to bike power so the voltage is consistant. I'm sure you;ve all experienced the problem of hearing, but people not able to respond. Thats cos the receive requires far less power than a transmit, reducing the effective battery life very quickly.
Paul & Chris (Reaper and Speighty581)
On 1 run we were getting a clear transmitt and recieve over a mile range, but it`s also been down to just 20 foot.
So Chris and myself decided that we needed to find out why and herein is what we found out, with the help of a couple of friends and the internet.
The Cobra radios that most of us are using are in fact 2 way walky talkies and so are designed with that in mind. What we mean is that for them to work at there best they should be held in your hand near your mouth/ear. When in this position the arial will be vertical and that`s when it works best.
Now some riders keep there radio (like me) in there jacket pocket, others under there seat and others in there tank bag.
Now the problem here is that all 3 of the descibed ways will cut down on the range of the radios, especially if the radio is laid horizontal.
Most of us run the radios on rechargable batteries. This will also cut the effectivness of the radios as they are designed to run on 6 volts and the rechargable type batteries only put out 4.8 volts. Added to this they only put out there max power for around an hour. So as you can see these things also go against the radios working.
Now what would be an ideal answer to all of this isn`t so easy to impliment.
First the power is easy to deal with, by either using normal batteries or better still the bikes power after being dropped to the required 6 volts. We will be posting a simple to make and cheap way of doing this in the near future.
Second and this is were the law comes in. The law for these radios states that they cannot have a detachable aerial and must not excede a maximum output of 500mw. Now it is easy enough to get around the aerial problem by simply attaching and aerial to the bike and running a lead to the radio and sealing it in. When we tried this we got another 20 yards reception which for the trouble and cost was not worth the agro.
The effective range of the standard PMR is quoted on one source to be 400mts. Thats probably about right in real life usage, we have all suffered from a lack of transmitting range, it's well known that these units can receive for a longer distance than it can transmit. Making it quite hit and miss on many of the runs and less of an effective means of communication. I can think of several times when the back marker cannot communicate with the front marker. Which is a real pain at times, adding to the stress levels of all run organiser.
In practicality there are ways listed below that can help sort all of the problems out, or at least increase the effective range of these units. But the only real way to do it is to spend money on the pro-kit. To that end both myself (Reaper and Speighty581) are getting units that are capable of effective transmit and recieve ranges, and will let you know how well it works....also, where we attend runs, will make effective use of the system to keep both front and rear markers in communication.
So what do you need to do to maximise your enjoyment of the PMR radios.
1 - Keep the unit and therefore the aerial vertical and away from your body and the area of the bikes alternator (which produces a magnetic field). Try to get it as high as possible and don`t cover it in anyway. Another place not to mount the radio is inside the nose fairing, the frame. tank and your body absorbs most of the signal. If you keep it on you, have it on the outside of the body, belt clip is ideal...in the underarm area.
Keeping it vertical is very imporant, the orientation of the signal is quite important. Otherwise your again reducing the effective range of the unit.
2 - Run the radio on batteries that add upto the recomended voltage. Better still convert it to bike power so the voltage is consistant. I'm sure you;ve all experienced the problem of hearing, but people not able to respond. Thats cos the receive requires far less power than a transmit, reducing the effective battery life very quickly.
Paul & Chris (Reaper and Speighty581)