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Mobile Antenna SWR issues with different lengths antennas

I just recently purchased a skipshooter 7 ft antenna for a base application and works fairly well after mass tuning of the antenna.
The tunable tip had to be cut off along with 2 and a quarter inches of wire from the top to get swr down to 1.5 on channel 1 cb band and 2.0 on channel 40 so i cut off 1 more inch and it set just rite for cb band around 1.2 on 1 and 40.
Just like having a 102 inch steel whip without all the electrical noise im satisfied using this skipshooter as a base antenna.
 
turborich said:
Hello folks,

I've been into CB radio for years, I have a base and 3 mobile set ups. On two of the mobile rigs I have roof mounted antennas and don't have any issues.

So here's the issue. I have an old jeep wrangler yj. I installed a Uniden 980 USB along with a little RM Italy KL 203 amp. Lowered the dead key on the radio, opened up modulation to 100% and it's a great low power set up. I have the standard 18 ft length of coax, using RG-58 since we're only talking about 175 watts pep. I bought the standard mount for behind the taillight, I have made sure the mount is grounded to the body of the jeep. Running the coax to the antenna without any coils, all has been checked, no shorts, good continuity, etc.

When using a 4 foot firestick antenna with tunable tip I have no problem achieving a 1.08 swr at 52 ohms. However when I try using a 5 or 6 foot skip shooter antenna with tunable tip I can't get the SWR below 2.8 at 130 ohms. My buddy brought over his rig expert analyzer over and we checked it. This is at the end of the coax hooked into the analyzer. Radio and amp out of the picture.

He's a long time CB'er and said certain antennas work better with certain vehicles. Now I understand that having the antenna mounted above the taillight isn't ideal and the roof is always the best location, however my roof is fiberglass so it's not an option. What would cause this and is there an easy fix? Basically a 4 foot antenna works great and the numbers are right, anything longer and the numbers jump up so I don't want to risk it. I did ask for a radio check from 4 miles away with the 4 foot antenna and he reported back that my signal was a 9 over 13. I tried the 6 foot skip shooter with the high SWR's and he reported my signal increased to a 10 over 19. Even so, I'm leery to run it until I can get the numbers lower.

Any ideas? I figured I'd ask before I start experimenting with coax length, etc.

Thanks!View attachment 35646
Click to expand...
My 7 ft skipshhoter had to be cut down alot to use for cb band.
The tunable tip has to be cut off along with 3 inches of wire from the top load and itll set in just rite on cb band.
But dont do it because it worked for me as we are useing our antennas in differant applications where mine is a base antenna.
 
turborich said:
Hello folks,

I've been into CB radio for years, I have a base and 3 mobile set ups. On two of the mobile rigs I have roof mounted antennas and don't have any issues.

So here's the issue. I have an old jeep wrangler yj. I installed a Uniden 980 USB along with a little RM Italy KL 203 amp. Lowered the dead key on the radio, opened up modulation to 100% and it's a great low power set up. I have the standard 18 ft length of coax, using RG-58 since we're only talking about 175 watts pep. I bought the standard mount for behind the taillight, I have made sure the mount is grounded to the body of the jeep. Running the coax to the antenna without any coils, all has been checked, no shorts, good continuity, etc.

When using a 4 foot firestick antenna with tunable tip I have no problem achieving a 1.08 swr at 52 ohms. However when I try using a 5 or 6 foot skip shooter antenna with tunable tip I can't get the SWR below 2.8 at 130 ohms. My buddy brought over his rig expert analyzer over and we checked it. This is at the end of the coax hooked into the analyzer. Radio and amp out of the picture.

He's a long time CB'er and said certain antennas work better with certain vehicles. Now I understand that having the antenna mounted above the taillight isn't ideal and the roof is always the best location, however my roof is fiberglass so it's not an option. What would cause this and is there an easy fix? Basically a 4 foot antenna works great and the numbers are right, anything longer and the numbers jump up so I don't want to risk it. I did ask for a radio check from 4 miles away with the 4 foot antenna and he reported back that my signal was a 9 over 13. I tried the 6 foot skip shooter with the high SWR's and he reported my signal increased to a 10 over 19. Even so, I'm leery to run it until I can get the numbers lower.

Any ideas? I figured I'd ask before I start experimenting with coax length, etc.

Thanks!View attachment 35646
Click to expand...
big time reflection.. it takes 3 square feet to allow the antenna to work.. the base of the load needs to be at least 18 inches feet from obstruction AND above any.. rflection.. stop listening to cb tune up guys.. i am a retired ham/cb repairman 40 + yrs.
 
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Squints said:
I just recently purchased a skipshooter 7 ft antenna for a base application and works fairly well after mass tuning of the antenna.
The tunable tip had to be cut off along with 2 and a quarter inches of wire from the top to get swr down to 1.5 on channel 1 cb band and 2.0 on channel 40 so i cut off 1 more inch and it set just rite for cb band around 1.2 on 1 and 40.
Just like having a 102 inch steel whip without all the electrical noise im satisfied using this skipshooter as a base antenna.
Click to expand...
I have a very basic question here. It seems you saw an SWR of 1.5 on channel 1, and an SWR of 2 on channel 40. I had something similar when I was tuning my K30 antenna. I know my antenna is different than yours but I figured SWR behaves the same as you tune one. I figured as the SWR comes down on 40 it will rise on 1 until both of them meet in the middle, provided a person doesn’t cut too much off and have it go the other way. So the best I was able to do was 1.75 on both channels 1 and 40. But somehow you saw the SWR continue to drop on both channels and finally saw a 1.2 on channel 1. How is this possible? Did I misunderstand by thinking the SWR will only meet in the middle and cannot actually go lower? I reached 1.75 and I trimmed 1/8 off again and the SWR on 1 went above what it was on 40 so I had to raise the antenna slightly to put it back to 1.75 on both channels. Based on that I didn’t think a lower SWR was possible.
 
Last edited:
This goes to another question of "If the antenna does this at this spot, but does this at the other spot - which is better?

Many tend to forget the Location helps with Resonance, which then affects BANDWIDTH - or how well the antennas resonate for the width of frequencies you will use.

You're seeing this effect.

In some locations it's VERY Resonate LOW SWR at one spot and on one frequency.

But move it several feet, or even inches, it's different?

Why - Location and the ability of the antenna to work that particular location o the vehicle gives the system this type of response.

If you're more worried about how the antenna looks on the vehicle, than providing for the antenna so you can use the radio with the vehicle - you'll need to step back and re-asses your situation and rework your plans, including trying another type of mounting, location, or even forget about it because you're in a difficult lease or loan issue with the vehicle when it comes to resale.
 
turborich said:
Hello folks,

I've been into CB radio for years, I have a base and 3 mobile set ups. On two of the mobile rigs I have roof mounted antennas and don't have any issues.

So here's the issue. I have an old jeep wrangler yj. I installed a Uniden 980 USB along with a little RM Italy KL 203 amp. Lowered the dead key on the radio, opened up modulation to 100% and it's a great low power set up. I have the standard 18 ft length of coax, using RG-58 since we're only talking about 175 watts pep. I bought the standard mount for behind the taillight, I have made sure the mount is grounded to the body of the jeep. Running the coax to the antenna without any coils, all has been checked, no shorts, good continuity, etc.

When using a 4 foot firestick antenna with tunable tip I have no problem achieving a 1.08 swr at 52 ohms. However when I try using a 5 or 6 foot skip shooter antenna with tunable tip I can't get the SWR below 2.8 at 130 ohms. My buddy brought over his rig expert analyzer over and we checked it. This is at the end of the coax hooked into the analyzer. Radio and amp out of the picture.

He's a long time CB'er and said certain antennas work better with certain vehicles. Now I understand that having the antenna mounted above the taillight isn't ideal and the roof is always the best location, however my roof is fiberglass so it's not an option. What would cause this and is there an easy fix? Basically a 4 foot antenna works great and the numbers are right, anything longer and the numbers jump up so I don't want to risk it. I did ask for a radio check from 4 miles away with the 4 foot antenna and he reported back that my signal was a 9 over 13. I tried the 6 foot skip shooter with the high SWR's and he reported my signal increased to a 10 over 19. Even so, I'm leery to run it until I can get the numbers lower.

Any ideas? I figured I'd ask before I start experimenting with coax length, etc.

Thanks!View attachment 35646
Click to expand...
9 over 13? I'd love to see a picture of what that looks like on an S Meter. I have been playing radio since 1965 & I have never heard of such a report? Sounds like something somebody just made up because they don't know how to read the S Meter or something because there is No 13 on any meters I've ever seen.
 

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