 |
Welcome to Motorcycle-communications.com
Specializing in Motorcycle
Communications & Accessories |
 |
| Sales 800-917-6698 |
| Sales * Service & Repair * Headset Installation * Custom Installation |
|
|
|
 |
Servicing Your Equipment
More Info! |
Shipping to Canada, the US, UK and Australia.
Offering support via email, chat and phone. |
     |
Advanced
Search |
 |
|
| Check out our other Communications web site. Communications for Cars, Trucks, & Home! Click Here |
|
|
My communicating distance fluctuates. One day it's great the next it's poor. Why ? |
Our first recommendation of course is to have your system checked out. Once your system has been given the thumbs up consider other factors such as the length and type of your antenna, performance characteristics of your radio - tuned or stock? and finally terrain and atmospheric conditions.
Read on for a scientific explanation of what is really going on under the hood so to speak. |
|
| The radio Sun |
Scientists track solar cycles
by counting sunspots -- cool planet-sized areas on the Sun where intense
magnetic loops poke through the star's visible surface.
Hathaway is
an expert forecaster of sunspot numbers. "Sunspot counts peaked
in 2000 some months earlier than we expected," he recalls. |
|
During solar maximum, magnetic fields above the Sun's surface become
impressively tangled, particularly near sunspots.
Twisted magnetic
fields -- stretched like taut rubber bands -- can snap back and explode,
powering solar flares and coronal mass ejections. |
The
subsequent dip toward solar minimum seemed premature to Hathaway,
and indeed it was. Before long, sunspot counts reversed course and
began to climb toward a second maximum that now appears to be only
a few percent smaller than the first.
Solar Max eleven years ago was much the same. A first peak arrived
in mid-1989 followed by a smaller maximum in early 1991. |
 |
Sunspots are the most visible sign of those complex magnetic fields
-- but not the only one. Another sign is solar radio emissions, which
come from hot gas trapped in magnetic loops.
"The radio Sun is
even brighter now than it was in 2000," says Hathaway.
By the
radio standard, this second peak is larger than the first. |
 |
| In fact,
if the ongoing cycle proves to be a double, it will be the third such
double-peaked cycle in a row.
The last two sunspot cycles also had double-featured maxima. |
| Conclusion! |
| Hathaway notes a widespread misconception that solar activity varies
every 11 years "like a pure sinusoid." In fact, he says,
solar activity is chaotic; there is more than one period. |
|
Earth-directed solar explosions, for instance, tend to happen every
27 days -- the time it takes for sunspots to rotate once around the
Sun. There is also an occasional 155-day cycle of solar flares. No
one knows what causes it. And the double peaks of recent solar maxima
are separated by approximately 18 months. |
| So what does it all mean? Can anything be done? |
|
What you hear is static. This static commonly referred to as "White Noise" is directly tied to the distance you can communicate. The higher the white noise the less distance you will communicate.
There are improvements you can make to increase your range.
- Change your antenna to a longer antenna and have it tuned.
- Improve the ground path of the antenna (packing down volts). Remember paint and primer are insulators.
- Tune the radio - Expect a 30% - 50% improvement from performance tuning.
- Speech compression - expect 100% - 200% improvement by adding a compression device to the system.
| Q & A |
- I have a J&M CB and would like to increase the communicating distance. What can be done?
|
|
- There are several areas that can normally be improved upon.
A) If you are using a 1 or 2 foot antenna upgrade to a 3 or 4 foot Firestik FL or FS series antenna and tune the antenna for optimal SWR.
B) Remove the paint and primer on all bolts from the antenna stud mount all the way back to the frame.
C) Performance tune the radio. We tune the transmitter and receiver for optimum output and receive sensitivity. Expected gain is 50% on transmit & 30% on receive.
|
- Why do you recommend a Firestik antenna over the J&M?
|
- The Firestik antenna is more rugged, has more metal mass and has a tunable tip making the tuning of the SWR a snap.
|
- Where is the best mounting location for the antenna system?
|
- All the way to the back of the bike. The license plate type mount offered by J&M is an excellent choice for most bikes. We highly recommend making a change to the mount. The ground strap that is included should be removed from the stud. Drill a hole in the bracket, remove the powder coating and re-attach the ground strap. Adding a second ground to & attaching to a different ground potential should be considered.
|
- How many feet of antenna coax cable do you recommend and why?
|
- We recommend 18 feet of antenna coax lead but that is not the only consideration. The chart to the left illustrates a phase shift. This shift has to do the velocity factory of the coax and the resonate frequency of the antenna. With 18 feet you are in phase.
There are two types of coax dialectics to consider, poly-foam and polyvinyl. These materials are used to separate the center conductor from the outer shielding. Poly foam is more flexible but has a much lower melting point. Motorcycles exhaust pipes are HOT HOT HOT. We use poly vinyl coax for motorcycles.
Secondly there are two center conductor options, solid core and multi strand center conductor. We use only multi strand center conductor type coax. It will hold up much longer without breaking.
Finally there are different shielding percentages available. Typically from 70% to 95%. We use 95% shielding. The higher the percentage the lower the loss.
|
| We agree that other lengths of coax will work. The SWR may look great but the antenna system will be out of phase and the Db gain will suffer. Bottom line- loss in performance and No the SWR is not a measurement of performance. You are only adjusting the resonate freq of the antenna. |
- How much range should I expect out of my system?
|
- There are MANY factors to this equation from the length of your antenna, length of coax, brand of antenna- they are not all equal - antenna SWR tuned?, has proper antenna ground been achieved?, has the radio been performance tuned? how about all of the above for the biker you are communicating with and how much (white noise) are you experiencing today. (White noise) changes daily. Below is approximations only.
1) Short antenna (6 inch rubber duck) non tuned radio. Approximately 50-100 yards.
2) Short antenna (1-2 foot) non tuned radio. Approximately 1/4 to 1/2 mile.
3) Long antenna (3-4 foot) and non tuned radio. Approximately 3/4 to 1 1/2 miles.
4) Performance tune the J&M radio - increase by 40-50%
5) Add our compressor to a GL1800 or a Harley - 5 miles typical.
|
- My factory system wont perform (has no distance). I have had it checked out and the dealership claims there is nothing wrong. What can I do?
|
- There are several improvements that can be made especially with the Harley Davidson and Honda GL1800 systems.
Both brands have poor ground on the antenna systems. The Harley can be improved with short braided straps. (NO WIRES) the material must be a basket weave type and wide 3/4 of an inch and short. Do not exceed 24 inches. At this freq ground runs on top of the wire not through it and only for a short distance.
The GL1800 has a ground problem with the antenna mounting bracket. Remove it and file both sides at both ends and put it back on. Set the SWR.
Consider our compressor for these two bike types. No significant gain can be achieved from tuning the radio. Modulation (output) is very weak on both. Typically 10-20% modulation. The modulation is increased to 75-85% with the compressor.
|
- My intercom sounds great but people on other bikes tell me they can't understand me. What can be wrong?
|
- More than likely you have an antenna system or a CB radio problem. If the problem were the headsets or headset cords the intercom would be distorted as well.
Basic troubleshooting procedures require a process of elimination in order to get to the culprit. And remember easy & cheap 1st, hardest and expensive last.
Can anyone understand your passenger? The likelihood of both headsets being defective is extremely low. If you are experiencing similar results from both headsets move on, it's not the headsets.
Antenna system is next. With the antenna system you have coax, stud mount, antenna, and ground. Check them out in this order - ground, antenna, stud mount and coax. If you move the coax or grab the antenna bracket and the SWR fluctuates you have a ground problem. The SWR should be below a 2.0 and not fluctuate more than .1 up or down when moving the coax or grabbing the bracket. In other words 1.9-2.1 of fluctuation is ok. Remember, paint and primer are your enemy. Pinched or melted coax jacket is not good- replace it. Spin the antenna in a circular direction and check the SWR. Look for serious fluctuation or a spike. If it exhibits either replace it and same for the stud mount is screws into.
If none of the above resolves your problem and you can't find a local professional that can resolve your issue, bring it to us. We will resolve your issue.
Please call for an appointment before showing up unless you intend to leave the bike as we may be booked for the day.
|
|
|
|
|
|
|
| Quick Links to Motorcycle Related Consumer Electronics |
|
|
|
|
|
 |
  |
|
|
|
|
Motorcycle
Events/Rally's |
 |
 |
| © 2005 - 2011 All rights reserved |
Mail to/ship to address:
High Tech Mobile Communications LLC
402 Palo Pinto Street,
Weatherford, TX 76086 |
|
|
|
