[GilbertGL]

imported post

My 1983 GL1100 Interstate came to me with one of those very long radio/CB antennas with the coil thingy half way up it.

Although I have the Clarion II AM/FM radio, I do not have the internals for the CB, and I really do not want to bother with CB.

My question is, can I exchange that long antenna for something shorter (like one on a car) and still receive AM/FM radio OK?

Thanks,

Gilbert

 

[tricky]

imported post

A long time ago some one said to me " you want more signal? stick up more wire"
You could try replacing the antenna but with a shorter antenna you might risk blocking the signal with your body, who knows? give it a try, you can always put the other one back on if it doesnt work

 

[exavid]

imported post

Yes, you can change to a shorter antenna. If you experience any degradation in reception it will show up on the AM band, the FM should be fine. Usually automotive receivers will have an screw adjustment somewhere on the chassis for antenna tuning. The quick and dirty way to tune is to select an AM station somewhere near the middle of the band or near your favorite station and tune for max volume. This isn't the proper way to get even tuning over the whole band but it will work well enough and will give best results for you favorite station. The

 

[axelwik]

imported post

A CB antenna which is resonant on 27 MHz really isn't the right antenna for AM or FM reception anyway. You will probably get better reception with an antenna designed for the broadcast bands than a CB antenna, even if it's shorter.

Antenna resonance is inversly proportional to length - the lower the frequency, thebigger the antenna. Broadcast FM is at around 100 MHz. A 100 MHz antenna is much shorter than a 27 MHz antenna (given the same design) and will work better thanthe non-resonant CB antenna.

AM reception is usually a compromise with most FM antennas since it uses a much lower frequency, but most people don't use AM so it's not noticed.Reception of AMcan also be very noisy on a motorcycle with close proximity of the ignition system and other unshielded electrical components.

 

[exavid]

imported post

axelwik wrote:

A CB antenna which is resonant on 27 MHz really isn't the right antenna for AM or FM reception anyway. You will probably get better reception with an antenna designed for the broadcast bands than a CB antenna, even if it's shorter.

True, however a CB antenna is usually electrically longer than the typical AM/FM auto antenna to keep transmitter efficiency up.

Antenna resonance is inversly proportional to length - the lower the frequency, thebigger the antenna. Broadcast FM is at around 100 MHz. A 100 MHz antenna is much shorter than a 27 MHz antenna (given the same design) and will work better thanthe non-resonant CB antenna.

Usually a CB antenna and an FM antenna aren't designed the same. an FM antenna for a car (or bike) is usually a straight whip, tuned somewhere near midband, where a CB antenna is usually center or end loaded to make it electrically much longer than it is physically. Actual length of the antenna doesn't tell the whole story since the input network of the receiver has a lot to do with it too. The CB antenna has to be reasonably tuned since the transmitter has less than 5W rms to work with. The FM station is using several thousand watts.

AM reception is usually a compromise with most FM antennas since it uses a much lower frequency, but most people don't use AM so it's not noticed.Reception of AMcan also be very noisy on a motorcycle with close proximity of the ignition system and other unshielded electrical components.

AM antennas are a compromise, you'd have to mount a tower on your car to get a reasonable fraction of a wavelength. On the other hand AM stations broadcast with a lot more power which helpsmake upfor the overly short antenna. Reception of AM signals has been excellent on both my 1200 and 1500. The OEM radios are designed with the motorcycle constraints in mind. A Goldwing's electrical system isn't inherently any noisier than any otherautomotive installation. I don't hear any engine or alternator noise in my radio even on the AM band tuned off station.

 

[GWNorman]

imported post

The Sierras are very neat, but the can break inside easily if kids start meddling with them.

 

[GilbertGL]

imported post

Thanks for all your input guys. I'm going to do a bit of investigating myself now. I've had that long CB whip antenna broken twice by meddlers, so it's got to be replaced with something shorter.

Thanks,

Gilbert