CB limited range
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Stage IV
Joined: Mar 2009
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CB limited range
I added the CB option to my 09 Street Glide and it seems that the range is really limited. no problems within 1/2 mile but after that it does not seem to transmit or recieve any further. I amusing the HD cb module for my radio and the HD antenna. Anyone have the same experience and or suggestions?
Road Warrior
Joined: Oct 2008
Posts: 1,334
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From: Rosamond, Cali
It means Standing Wave Ratio (SWR). It is the amount of power 'reflected' back to the transmitter that is NOT broadcast by the antenna in comparison to the amount of power that IS broadcast.
A transmitter puts out the greatest amount of its available power when it transmits into a load that's matched to its power output section, the part of the radio that amplifies your radio signal. Your CB is rated for about 4 watts into a 50 ohm 'load' (impedance). You can adjust an antenna's load impedance by changing the antenna's length. You want to change the length of the antenna, lengthen it or shorten it, so that its load impedance matches that of the transmitter. This will give you the most power output, when the antenna is the right length. A one-to-one (1:1) 'match' between antenna and transmitter is perfect. That means for every watt the radio puts out, a watt is broadcast (or nearly so). A 1:1 match means the antenna is the correct length. Yours might be a little too short, or a little too long.
Most mobile CB antennas have a little set screw at the base of the antenna, you loosen it and you can slide the antenna up (longer) or down (shorter) to match it to the radio. To do this, you need an SWR meter. The radio probably has one built in. You key up the radio, count into the microphone, and watch the SWR meter. Adjust the length of the antenna--longer, or shorter--until the SWR meter deflects the least amount when you speak into the microphone and broadcast. Move the antenna maybe 1/4" at a time. Then transmit your voice again. If you're going the right way with the antenna, the SWR meter should start to deflect less. For example, if you're making the antenna longer and you should be shortening the antenna, then the SWR meter will either deflect a little more each time you transmit after changing the antenna length, or will be at its maximum deflection and won't change.
If you move the antenna to its maximum and minimum lengths, and the SWR meter continues to deflect to its maximum at all test points, then you likely have another issue. On the other hand, if you key the radio up and count and the SWR meter doesn't deflect, or deflects only a little, you're already adjusted for best power transfer between the radio and antenna.
It can be a little confusing at first. As the prior poster said, take it to a shop and they can probably adjust it for a few bucks.
If your radio doesn't have an SWR meter, find a "CB" friend who has a standalone unit, and have him help you. He'll put the meter in-line temporarily with the antenna as he adjusts the antenna's length.
Modern radios will reduce their output power if they transmit into a load that's worse than about 2:1. Recall 1:1 means 50 ohm transmitter into a 50 ohm load. 2:1 means 50 ohm transmitter into a more than 50 or less than 50 ohm load. Note the important part is that the impedance matches, not the value of the impedance, per se.
So, basically, you might well need to adjust your antenna to make it more efficient, i.e. to enable the radio to output the optimum amount of its available 4 watts.
The nature of a motorcycle mobile antenna is not to be very efficient. There is not a great deal of metal which kind of restricts the efficiency of the antenna. Also, generally motorcycle antenna's are inherently inefficient due to their compact size.
Funny thing about high frequency radios is that a guy a mile away might not hear you--but a guy 1500 miles away can hear you loud and clear. But that's a whole other story. Hope this helps.
Alan
A transmitter puts out the greatest amount of its available power when it transmits into a load that's matched to its power output section, the part of the radio that amplifies your radio signal. Your CB is rated for about 4 watts into a 50 ohm 'load' (impedance). You can adjust an antenna's load impedance by changing the antenna's length. You want to change the length of the antenna, lengthen it or shorten it, so that its load impedance matches that of the transmitter. This will give you the most power output, when the antenna is the right length. A one-to-one (1:1) 'match' between antenna and transmitter is perfect. That means for every watt the radio puts out, a watt is broadcast (or nearly so). A 1:1 match means the antenna is the correct length. Yours might be a little too short, or a little too long.
Most mobile CB antennas have a little set screw at the base of the antenna, you loosen it and you can slide the antenna up (longer) or down (shorter) to match it to the radio. To do this, you need an SWR meter. The radio probably has one built in. You key up the radio, count into the microphone, and watch the SWR meter. Adjust the length of the antenna--longer, or shorter--until the SWR meter deflects the least amount when you speak into the microphone and broadcast. Move the antenna maybe 1/4" at a time. Then transmit your voice again. If you're going the right way with the antenna, the SWR meter should start to deflect less. For example, if you're making the antenna longer and you should be shortening the antenna, then the SWR meter will either deflect a little more each time you transmit after changing the antenna length, or will be at its maximum deflection and won't change.
If you move the antenna to its maximum and minimum lengths, and the SWR meter continues to deflect to its maximum at all test points, then you likely have another issue. On the other hand, if you key the radio up and count and the SWR meter doesn't deflect, or deflects only a little, you're already adjusted for best power transfer between the radio and antenna.
It can be a little confusing at first. As the prior poster said, take it to a shop and they can probably adjust it for a few bucks.
If your radio doesn't have an SWR meter, find a "CB" friend who has a standalone unit, and have him help you. He'll put the meter in-line temporarily with the antenna as he adjusts the antenna's length.
Modern radios will reduce their output power if they transmit into a load that's worse than about 2:1. Recall 1:1 means 50 ohm transmitter into a 50 ohm load. 2:1 means 50 ohm transmitter into a more than 50 or less than 50 ohm load. Note the important part is that the impedance matches, not the value of the impedance, per se.
So, basically, you might well need to adjust your antenna to make it more efficient, i.e. to enable the radio to output the optimum amount of its available 4 watts.
The nature of a motorcycle mobile antenna is not to be very efficient. There is not a great deal of metal which kind of restricts the efficiency of the antenna. Also, generally motorcycle antenna's are inherently inefficient due to their compact size.
Funny thing about high frequency radios is that a guy a mile away might not hear you--but a guy 1500 miles away can hear you loud and clear. But that's a whole other story. Hope this helps.
Alan
Last edited by AlanStansbery; Mar 2, 2009 at 11:11 AM.
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Cruiser
Joined: Jul 2008
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From: Alabama
Don't expect to talk too far on them. It is not like a car or truck. There is not enough of a plane on a bike to generate much distance. I can talk about a mile on mine at the most. Turn your squelch down a little bit and you might can too.