I cannot emphasize enough the importance of the following:
- QUALITY antenna
- QUALITY feedline
- SUFFICIENT ground
Honestly, I do not care for the J&M brand antenna - it does not cut the mustard in terms of build quality and grounding abilities.
Antenna...
I would use a more sturdy Firestik or Wilson brand fiberglass antenna. With the saddlebags installed, the 3' antenna works fine. However, I do not recommend going with a shorty 2' stick because the radiation pattern will be blocked if you follow my mounting suggestion. Regardless of the style, opt for the adjustable tunable tip model (those with a screw top). Cut-to-tune antennae are more difficult because they are easy to over-shorten (cut down too far) and once this happens the antenna is about as good as garbage.
Feedline...
I know it is somewhat pricey per foot, but you can get away with a weaker ground plane that motorcycles provide by using higher quality, ultra low loss coaxial cable. I opted for Times Microwave LMR400 Ultra Flex. This is an outdoor cable that can take a pounding. The center conductor of Ultra Flex is stranded (not solid), so it can make the tight bends required for bike install without the concern of breaking the core. Any ham or electronics retailer should be able to locate this for you. Also check Ebay for premade cables.
Grounding your setup...
Motorcycles pose a significant challenge for providing sufficient amount of grounding material because they are small, lightweight and often use plastics. The V-Star Customs are particularly difficult because of the plastic rear fender. Ideally, the following should be observed:
- Use 12ga wire as a minimum if a separate ground wire is used. This is the case of the J&M brand, and they skimp on the ground wire - I recommend a braided copper strap.
- Use as much coax feedline as you can during the install.
- You MUST have at least 9 contiguous square feet of metallic grounding material. The frame and fenders of most bikes can provide this if there are no insulating bushings to prevent the contiguous surface. If 9sq/ft are not directly available, install approx 17' of feedline (RG-8X is fine), and do not coil it.
- Try to minimize anything that blocks the radiating pattern of the antenna (luggage, flags, etc). The antenna is most efficient when it has a direct path to the recipient.
Mounting your antenna on a V-Star 950/1300 Tourers...
The 950 and 1300 Tourers provide an excellent antenna mounting point on their saddlebag mounts. A simple piece of angle iron can be cut and used as a bracket for attaching the antenna to the mount.
Your local truck stop carries a multitude of CB install and test equipment. A few things you will want to pick up there are:
- a SWR meter (to measure efficiency so that you don't burn up your new transmitter - YES, it CAN easily happen if a solid ground is not achieved)
- the antenna
- a stud mount to connect the antenna to the angle iron bracket.
Installing the radio...
One tip is to loosen the tank to feed the coax cable and J&M connections through easier. Make connections per J&M's instructions. You may also want to use dielectric grease between the male and female connections. It is a non-conductive sealant to ward off moisture and corrosion at the connection points. The 1300 has a really handy neck cover where the bulk of the connections can be hidden. The front is an Allen head bolt and the rear is a screw-type pop rivet. Once both fasteners are removed, the neck cover comes off like a clam shell.
Finishing up the job....
This is where the SWR meter comes in handy. Connect the meter between the antenna and radio. Tune the radio to channel 10, on low power. Key the mike and watch where the needle spikes. Ideally, the SWR should be as close to 1 as possible. Anything up to 2.5 is acceptable, but the closer to 1, the better your buddies will hear your transmission. Move down to channel 1 (the motorcyclist's channel) and again key the mike. Observe where the needle spikes.
- If the SWR on channel 1 is higher than channel 10, then the system is short (physically and electrically). You will need to tune your antenna up by lengthening your tip.
- If the SWR of channel 1 is lower than channel 10, then the system is long. You will need to tune your antenna down. This is where an adjustable tip antenna is preferred.
If you have tuned your antenna to the longest setting and are still experiencing high SWR, then there is insufficient ground. If you have observed all the standard rules of grounding, then you need to get creative with creating a ground. You can add spring coils (again, found at truck stops), a heavier mounting stud, a longer (4') antenna, adding a metal plate behind the fender, etc.
Each time you test SWR, be sure you will be in a similar condition as when you will transmit. For example, test in an open area away from walls or other conductors, install luggage or have a passenger sit on the seat, and always replace the protective dust cap - even THAT will change your SWR.
Here's a good source for CB info and troubleshooting: http://www.firestik.com/Tech_Docs.htm
Enjoy the ride!
73! ... oh, wait, wrong band. Uh, "Over and out good buddy!"
No comments:
Post a Comment