4' Firestik tuning help - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > General Tech Forums > Communications and Electronics

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 01-07-2013, 07:24 PM   #1
Jeeper
 
BlueRidgeYJ's Avatar
 
Join Date: Mar 2012
Posts: 4,917
4' Firestik tuning help

So I got a firestik from Santa so I can look like a real jeep and I started to tune it in. On the low end I am ~2, mid was ~3, and high end was closer to 5+. I cut about a half inch, dropped but barely noticably. I cut an inch, dropped to 1.7, ~2.8, and ~4.5 or a lil over. I mostly talk on 146, so 2.8 is unacceptable (this is a 2M antenna, not CB - same principals, though).

Anybody else had a firestik that was WAY too long? I'm hesitant to go to town on it, don't want to go too far. I feel like I must be missing something here.

I test .01 collar to ground, pin to pin, and mount to batt neg. I test open on all cross checks. Insulating washer is good to go. No spring or disco. I replaced the annoying little cap between each test. I am in the same mounting spot where my Larson 2' whip got 1.5, 1.7, 1.5. Also, I replaced my RG-8X with RadioHack pl259, 'cause my mini8 didn't have duel pl259s. Mistake?

Love antenna otherwise, love the mount (front bumper), and it has better reception by far (duh).

Thanks fellers.

__________________
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
BlueRidgeYJ is offline   Quote Quick Reply
Old 01-07-2013, 08:41 PM   #2
Jeeper
 
BlueRidgeYJ's Avatar
 
Join Date: Mar 2012
Posts: 4,917
Quote:
Originally Posted by BlueRidgeYJ
... I am in the same mounting spot where my Larson 2' whip got 1.5, 1.7, 1.5. ...
1.7, 1.5, 1.7 - sorry.

__________________
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
BlueRidgeYJ is offline   Quote Quick Reply
Old 01-08-2013, 11:29 AM   #3
Supporting Member

WF Supporting Member
 
Wrong Way Hal's Avatar
 
Join Date: Jan 2012
Location: Ridgecrest, CA
Posts: 442
Hi BlueRidge,

Just to be clear, you are using the Firestick for CB, right? I ask because you mention that 2.8 (I'm assuming SWR) is too high for 146 (a 2M freq).

I would check to ensure you have a good RF ground. Remove the coax from either the antenna mount or from the back of the CB. Ensure the PL-259 cover is not touching ground. Check the ground side of the antenna to a very close body/frame ground point (a screw/bolt going into some sheetmetal). You want a point within inches of the antenna, if possible.

Ideally, the ground side of the antenna/mount should be connected physically to a good clean grounding point right at the base of the antenna. Depending on the shield of the coax to go all the way back to the radio and then the radio's ground wire to the battery to make your RF ground connection will cause problems.

I used an L shaped bracket to mount my antenna. The bracket came with some type of protective covering that I had to grind off in order to make a good ground connection. I also put star washers on both sides of the bracket to help with the connection.

73
__________________
Wrong Way Hal / 2012 Black JKR
Wrong Way Hal is offline   Quote Quick Reply
Old 01-08-2013, 02:31 PM   #4
Jeeper
 
BlueRidgeYJ's Avatar
 
Join Date: Mar 2012
Posts: 4,917
No sir, it is a Firestik 2M antenna.
http://www.firestik.com/Catalog/2M-4.htm

It is mounted to the bumper with a SS plate, I would think it has good bonding. Seems like it just is way too long.

Attachment 195850

73
__________________
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
BlueRidgeYJ is offline   Quote Quick Reply
Old 01-08-2013, 04:43 PM   #5
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 30,871
Images: 2
Did you scrape the anodizing off the bumper so the antenna mounting plate is getting a good solid RF (not just DC) ground through the bumper? Is the bumper itself well grounded? I have never measured the resistance from the OE bumper to chassis ground, not too sure if it is grounded well enough due to the presence of anodizing on so many of the surfaces between the antenna mount & chassis of the Jeep.
__________________
When you have a choice, buy American.

Jerry Bransford is online now   Quote Quick Reply
Old 01-08-2013, 07:00 PM   #6
Supporting Member

WF Supporting Member
 
Wrong Way Hal's Avatar
 
Join Date: Jan 2012
Location: Ridgecrest, CA
Posts: 442
X2.

Not that I know all manufacturers, but in over 30 years of hamming, never knew that Firestick made a 2M antenna. Sorry about that.

After scrapping off some of the covering (anodizing stuff??) around the mounting holes, this would be a good place to insert some star washers.

Another option, or addition, would be to run a VERY SHORT length of grounding braid from the antenna mount to a hole in the frame. Make sure again that you grind off the material on the frame so you get some shiny metal. Use star washers between the braid and frame.

Do you have or have access to an antenna analyzer, such as a MFJ-269? If so, where is the antenna resonate right now? If you don't have an analyzer, what is the SWR at 144, 145, 146, 147 and 148? That will help determine if the antenna is short or long.

And, one of the issues with 5/8 wave antennas, is that they NEED a ground plane under them in order to give you that "lowest" radiation pattern available. Whether it's a CB antenna or Amateur, ideally 5/8 wave antennas should be mounted in the center of the vehicle. 1/2 wave antennas don't require this.

73
__________________
Wrong Way Hal / 2012 Black JKR
Wrong Way Hal is offline   Quote Quick Reply
Old 01-08-2013, 07:43 PM   #7
Jeeper
 
BlueRidgeYJ's Avatar
 
Join Date: Mar 2012
Posts: 4,917
Quote:
Originally Posted by Jerry Bransford
Did you scrape the anodizing off the bumper so the antenna mounting plate is getting a good solid RF (not just DC) ground through the bumper? Is the bumper itself well grounded? I have never measured the resistance from the OE bumper to chassis ground, not too sure if it is grounded well enough due to the presence of anodizing on so many of the surfaces between the antenna mount & chassis of the Jeep.
A little bit.
Yes, I upgraded the body and frame grounds.
Bumper and frame both test good for resistance.

Quote:
Originally Posted by n6hal
X2.

Not that I know all manufacturers, but in over 30 years of hamming, never knew that Firestick made a 2M antenna. Sorry about that.

After scrapping off some of the covering (anodizing stuff??) around the mounting holes, this would be a good place to insert some star washers.

Another option, or addition, would be to run a VERY SHORT length of grounding braid from the antenna mount to a hole in the frame. Make sure again that you grind off the material on the frame so you get some shiny metal. Use star washers between the braid and frame.

Do you have or have access to an antenna analyzer, such as a MFJ-269? If so, where is the antenna resonate right now? If you don't have an analyzer, what is the SWR at 144, 145, 146, 147 and 148? That will help determine if the antenna is short or long.

And, one of the issues with 5/8 wave antennas, is that they NEED a ground plane under them in order to give you that "lowest" radiation pattern available. Whether it's a CB antenna or Amateur, ideally 5/8 wave antennas should be mounted in the center of the vehicle. 1/2 wave antennas don't require this.

73
I didn't, either. Mrs Claus made it in the workshop after I babbled on one day about my curiousity to try a fiberglass antenna.

No analyzer. I tested 144, 146, & 148, they came out about 1.7, 2.7ish, 4.5+ or something like that (it is in my first post). Too long, but like I said that was after I already took an inch and a half off. Just wanted to toss the question out before I cut a big ol chunk off this thing.

I would prefer a 1/2 wave, but it is what it is. I'd likely tear a 4' mounted on the cowl off the Jeep, lol, so bumper it is.

Thanks.
__________________
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
BlueRidgeYJ is offline   Quote Quick Reply
Old 01-08-2013, 08:05 PM   #8
Supporting Member

WF Supporting Member
 
Wrong Way Hal's Avatar
 
Join Date: Jan 2012
Location: Ridgecrest, CA
Posts: 442
Do you remember what the SWR numbers were for each point PRIOR to cutting the original 1.5" off? Did it make any difference cutting off 1.5"? If so, how much did the SWR change?

According to the antenna calculators, a 5/8 wave antenna for 146.000 should be 4.01', so right around 49" +-.

If by cutting off another 1/4", you see a noticeable change in the SWR, going in the right direction, I would probably continue. Just remember to take the readings exactly the same each time. If you were standing in the center/rear, stand there each time. Sitting, sit each time.

Another issue could be that you have the antenna too low. The antenna should be in the clear. The vertical portion of the vehicle's body is interacting with the antenna. Not much you can do about that except mount the antenna higher.

I've come to the conclusion that CB and Amateur antennas on Wranglers will ALWAYS be a compromise. Fiberglass hard tops don't provide a ground plane. Bumper/spare tire/corner mounts give directivity in the direction of the body and most of your signal goes up where no ground plane exists.

73
__________________
Wrong Way Hal / 2012 Black JKR
Wrong Way Hal is offline   Quote Quick Reply
Old 01-08-2013, 08:26 PM   #9
Jeeper
 
BlueRidgeYJ's Avatar
 
Join Date: Mar 2012
Posts: 4,917
Quote:
Originally Posted by n6hal
Do you remember what the SWR numbers were for each point PRIOR to cutting the original 1.5" off? Did it make any difference cutting off 1.5"? If so, how much did the SWR change?
...
I've come to the conclusion that CB and Amateur antennas on Wranglers will ALWAYS be a compromise. Fiberglass hard tops don't provide a ground plane. Bumper/spare tire/corner mounts give directivity in the direction of the body and most of your signal goes up where no ground plane exists.

73
Yes, a wee little bit (in the right direction).

Ain't that the truth. Here comes the hacksaw, I can always add a spring or washer if I cut too much. Hopefully it will pull down into a good range before I chomp it down to nothing.

I'll let y'all know what happens when the dust settles.
__________________
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”
BlueRidgeYJ is offline   Quote Quick Reply
Old 01-08-2013, 08:33 PM   #10
Supporting Member

WF Supporting Member
 
Wrong Way Hal's Avatar
 
Join Date: Jan 2012
Location: Ridgecrest, CA
Posts: 442
Yeah, by the time your done, I can see you cruising around with a little stubby-duck on the bumper. HI HI

__________________
Wrong Way Hal / 2012 Black JKR
Wrong Way Hal is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



logo carid shop wrangler parts carid fender flares custom wheels store avs deflectors at carid
» Rates
Get low rates on auto insurance in Canada!

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 09:37 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC