On Wed, 13 Apr 2005 15:14:22 -0700, "Paul Calman"
wrote in :

Hi. I have a cb unit mounted on a motorcycle. it is a J&M, linked here,
http://www.jmcorp.com/SeeProducts.asp?PF=24 , using the 3 foot Wilson
antenna on the page.
It's a pretty decent unit (kinda expensive, mine came with another bike) and
can be operated without looking at it, a good thing on a bike. I use it to
talk with other riders, but the maker says about 1/2 mile is all the range I
should get. On a straight piece of road it gets tough to use at 1 mile.
The reason I am told is that the bike has no ground plane, but I don't know
whether that affects reception or transmission. What's the story here?
I know Linear amps are a no-no, but I don't intend on doing skip, using it
often, or even talking much to base stations and truckers, and certainly
don't want to run some giant power unit that stomps on others transmissions,
but would be interested in using a small linear to boost transmission to a
max range of about ten miles, an acceptable distance when traveling cross
country with other bikes. Can any of you recommend what wattage would be
sufficient for this use without going overboard? Some of the problems to be
dealt with are a limited charging system, the inability to space wires far
from current and ignition units, and physical size. I would prefer to build
my own unit, rather that pay big bucks for garbage made in china. I have
seen schematics for sale for 30, 50, and 100 watt units. Know of any free
sources?
Other that a lecture on the illegality of linears, Do you have any useful
advice?


Forget about legalities -- the bike probably couldn't handle the
current of an amp. The problem is the lack of a ground plane. The bike
just isn't big enough to provide a good ground for the antenna. I know
of one solution but it requires a bit of shop work: Use a longer
antenna, and mount the bottom as low to the ground as possible, just a
few inches from the pavement, maybe on a bracket hanging from the rear
fender. The close proximity to the ground itself will provide a fairly
decent ground plane for the antenna even without a direct electrical
connection. I did this with my brother-in-law's Yamaha 1100 and it
worked great (well, it worked great the second time -- the first time
I mounted it too far to one side and it got scraped in a turn).

That's the best suggestion I have without getting a ham or GMRS
license and using a higher frequency.





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