Adjusting SWR on CB antenna?
#31
10-18-2007, 02:27 PM
#32
10-18-2007, 03:23 PM
Seasoned HDF Member
RE: Adjusting SWR on CB antenna?
I have a Classic with the one antenna, it was replaced with the J&M unit, radio reception is not as good but OK and I like the looks better.
Question? some have stated about using the Sierra splitter and using one antenna, I would like to put a CB on the classic and using one antenna sounds great, would I have to change to the CB antenna? Use the J&M or stock HD CB Antenna?
A little help here would be appreciated.
Thanks All
Question? some have stated about using the Sierra splitter and using one antenna, I would like to put a CB on the classic and using one antenna sounds great, would I have to change to the CB antenna? Use the J&M or stock HD CB Antenna?
A little help here would be appreciated.
Thanks All
#34
10-18-2007, 04:46 PM
Advanced
Join Date: Jul 2007
Location: Wichita, KS
Posts: 74
Likes: 0
Received 0 Likes
on
0 Posts
RE: Adjusting SWR on CB antenna?
Casper,
Sierra Electronics sells a "splitter" that will allow you to plug your am/fm radio, and your CB radio, into one coax that leads to one CB antenna. They also sell the antenna, for a total of $50 you get it all. You cannot use the Harley antenna that came with your bike, or the little rubber duckies that are so popular. You don't need to use the Sierra antenna, but you need to use a CB antenna that is loaded, not one that connects to a load like the stock Harley CB antenna (the loading coil is in the trunk).
On a motorcycle, two antennas so close together wil make the CB perform less that it could with only one antenna. By combining the fm antenna with the CB antenna, the CB will perform better. The FM should not suffer, but AM will suffer a little bit.
I'm going to test mine with a long steel whip too just for grins. I will use an antenna analyzer to set my swr for solo riding. Will make sure I'm in an open field when I do it.
Sierra Electronics sells a "splitter" that will allow you to plug your am/fm radio, and your CB radio, into one coax that leads to one CB antenna. They also sell the antenna, for a total of $50 you get it all. You cannot use the Harley antenna that came with your bike, or the little rubber duckies that are so popular. You don't need to use the Sierra antenna, but you need to use a CB antenna that is loaded, not one that connects to a load like the stock Harley CB antenna (the loading coil is in the trunk).
On a motorcycle, two antennas so close together wil make the CB perform less that it could with only one antenna. By combining the fm antenna with the CB antenna, the CB will perform better. The FM should not suffer, but AM will suffer a little bit.
I'm going to test mine with a long steel whip too just for grins. I will use an antenna analyzer to set my swr for solo riding. Will make sure I'm in an open field when I do it.
#35
10-18-2007, 05:13 PM
RE: Adjusting SWR on CB antenna?
the problem is that the antenna is a 1/4wave base loaded design, and expects to see an equal length (resonant) ground plane. Not sure how Harley if at all tuned it, but adding metal to the tourpak will definitely de-tune whatever they had. if you add rails, lights, rack, etc, they all have an effect. Best solution is to get some kind of a 3/8 or 5/8 wave length antenna that does not require as significant a ground plane, but they are not pretty. Here is one, but it is butt ugly for a motorcycle. At least mounted on the Tourpak it sould be, but mounted down on the fender, in black, a 2' section may not be too bad.
http://bobscb.com/antennas/firestik/firestik_mobile.htm
http://bobscb.com/antennas/firestik/firestik_mobile.htm
#37
10-20-2007, 10:31 PM
RE: Adjusting SWR on CB antenna?
To provide a ground plane and a tuned antenna, of course.
The previous poster is right though, if you want to really get out, you have to put a top loaded fiberglass whip, preferably a 48" one, attached to the saddle bag rail. Top loaded whips (the coil is in the top) don't require a ground plane to liberate the signal from the antenna so you will likely get five miles or more range. The factory ones are at best good for two miles, and the shorties even less.
Eons ago, when CB was real popular, I ran a setup like that on my '77 Electra Glide. It worked great. Base to mobile was a solid ten to twelve miles. mobile to mobile about five.
The previous poster is right though, if you want to really get out, you have to put a top loaded fiberglass whip, preferably a 48" one, attached to the saddle bag rail. Top loaded whips (the coil is in the top) don't require a ground plane to liberate the signal from the antenna so you will likely get five miles or more range. The factory ones are at best good for two miles, and the shorties even less.
Eons ago, when CB was real popular, I ran a setup like that on my '77 Electra Glide. It worked great. Base to mobile was a solid ten to twelve miles. mobile to mobile about five.
#38
10-20-2007, 10:44 PM
Road Captain
Join Date: Sep 2007
Location: Long Beach,Wa.
Posts: 602
Likes: 0
Received 0 Likes
on
0 Posts
RE: Adjusting SWR on CB antenna?
Another ham......Do you have any ham gear mounted on your bike????
ORIGINAL: Dr.Hess
Yes, an amplifier is illegal. Yes, lower SWR is better. Yes, antenna length is very important, even in a system with a 1:1 SWR. Yes, coils at the base of an antenna or in line with the coax increase the electrical length of the antenna. Yes, a motorcycle has crap for a ground plane.
You can purchase antennas designed specifically for vehicles with no ground plane, like fiberglass cars and snow mobiles. They won't look "cool" but they will work better than just a standard antenna on a bike. Do they still have CB shops? They might have them, or search online for the CB antenna makers. If you're getting a couple mile range with what you have stock, that's probably about as good as you're going to get without going to a much better antenna or more power (illegal).
You can also purchase a small tuning circuit to tune your antenna system for a lower SWR. I don't know how well it would work (retain settings) on something that vibrates as much as our bikes, but if your SWR is way off, like 2:1 or moreand you don't want to change your antenna, that might be something to look into.
Dr.Hess
NG6Y
Radio Electronics Officer, USMM (Ret.)
Yes, an amplifier is illegal. Yes, lower SWR is better. Yes, antenna length is very important, even in a system with a 1:1 SWR. Yes, coils at the base of an antenna or in line with the coax increase the electrical length of the antenna. Yes, a motorcycle has crap for a ground plane.
You can purchase antennas designed specifically for vehicles with no ground plane, like fiberglass cars and snow mobiles. They won't look "cool" but they will work better than just a standard antenna on a bike. Do they still have CB shops? They might have them, or search online for the CB antenna makers. If you're getting a couple mile range with what you have stock, that's probably about as good as you're going to get without going to a much better antenna or more power (illegal).
You can also purchase a small tuning circuit to tune your antenna system for a lower SWR. I don't know how well it would work (retain settings) on something that vibrates as much as our bikes, but if your SWR is way off, like 2:1 or moreand you don't want to change your antenna, that might be something to look into.
Dr.Hess
NG6Y
Radio Electronics Officer, USMM (Ret.)
#39
10-21-2007, 12:05 AM
Road Captain
Join Date: Feb 2006
Location: AZ
Posts: 503
Likes: 0
Received 0 Likes
on
0 Posts
RE: Adjusting SWR on CB antenna?
So hypothetically speaking of course sense its illegal to use an amplifier, where would you get one that would work on a motorcycle, could that cause damage to other componets on the bike? And on our older model Harley's that have the all in all radio would it work anyway?
#40
10-21-2007, 12:33 AM
RE: Adjusting SWR on CB antenna?
I have the rubber AM/FM and CB antennas from Freedom Cycles. At first, adjusting the SWR was (I thought( impossible. Not so! That knirled **** on the CB antenna only needs 1/8 to 1/4 turn to really change the reading! It is also a very loose and free moving thing. I found the spot (it took a while) and used rubber cement to hold that knurled **** right there.
My SWR reads at 1.025and has stayed steady. My receive range is an average of 2 to 3 miles and I can transmit to 2 miles or a bit more with no issues.
My SWR reads at 1.025and has stayed steady. My receive range is an average of 2 to 3 miles and I can transmit to 2 miles or a bit more with no issues.
Thread
Thread Starter
Forum
Replies
Last Post
