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Topic Review (Newest First)
05-10-2013 02:03 PM
CJChet I just installed my new swing away tire carrier from Groundpounder Fab. I had Eddie install a plate (per my design) on top of the swing away for a CB antenna and brake light. Here's what we came up with. I'm very happy with it.
05-10-2013 07:06 AM
Patrick H
Quote:
Originally Posted by DarrenT View Post
Nice. Those tail lights are sweet, where d'ya get those?
I'm gonna go get me a firestik and see what difference that makes.
Thanks for the input guys, very entertaining
Red 4" Round Stop Turn Tail Light 9 LED Surface Mount | eBay
05-10-2013 06:28 AM
DarrenT
Quote:
Originally Posted by Patrick H View Post
I was able to achieve 1.1 on ch.19 with a 4' Firestik II on this mount

Nice. Those tail lights are sweet, where d'ya get those?
I'm gonna go get me a firestik and see what difference that makes.
Thanks for the input guys, very entertaining
05-09-2013 10:38 PM
Patrick H I was able to achieve 1.1 on ch.19 with a 4' Firestik II on this mount

05-09-2013 10:24 PM
AC0QR Hey here's a post where cjnut claims either 1, or 1.1 with a tail-light mounted firestick:
http://www.wranglerforum.com/f5/cb-a...ml#post2179903

I'm surprised a whip mounted there could get such a low SWR. In retrospect, I probably didn't need to do my custom mount...
05-09-2013 07:54 PM
Jerry Bransford
Quote:
Originally Posted by AC0QR View Post
I'm thinking of cheap or improper coax (50 vs 75 ohm), or bends that mess up the outer shield/braid. But you're right, if none of those are a problem, then measuring SWR before or after feedline won't matter.

Using 75 ohm feedline on a 50 ohm output would make the SWR at least 1.5 right off the bat!
Why even bring that up? No one was talking about using 75 ohm coax any more than we were talking about using ac cord. Oh I forgot this is the internet.
05-09-2013 07:15 PM
DarrenT
05-09-2013 07:12 PM
AC0QR Oh no, I'm the one who started the geek speek. I felt bad for hijacking his thread
05-09-2013 07:10 PM
Patrick H
Quote:
Originally Posted by AC0QR View Post
Instead of hijacking OP's thread and arguing about geek-speak, here's some links with real peoples' SWR results for tail-light mounted antennae:

(dfry Reports 1.2):
http://www.wranglerforum.com/f5/cb-a...ml#post1009119

(tchaap reports 'very low'):
http://www.wranglerforum.com/f5/cb-a...ml#post1009318

(Tombo reports 1.6 to 2.8):
Cooltech Ultramount SWR help/suggestions

I think that the moral of the story is "2-3 is common but ok, less than 2 is good but harder to get"
Sorry, I didn't see where there was any arguing...
05-09-2013 07:10 PM
Patrick H
Quote:
Originally Posted by Jerry Bransford View Post
I hear you & hate it when that happens here in San Diego.
Yeah yeah, that's why I mentioned it. You may hear me, but you don't feel my pain..
05-09-2013 06:48 PM
AC0QR Instead of hijacking OP's thread and arguing about geek-speak, here's some links with real peoples' SWR results for tail-light mounted antennae:

(dfry Reports 1.2):
http://www.wranglerforum.com/f5/cb-a...ml#post1009119

(tchaap reports 'very low'):
http://www.wranglerforum.com/f5/cb-a...ml#post1009318

(Tombo reports 1.6 to 2.8):
Cooltech Ultramount SWR help/suggestions

I think that the moral of the story is "2-3 is common but ok, less than 2 is good but harder to get"
05-09-2013 06:40 PM
AC0QR I'm thinking of cheap or improper coax (50 vs 75 ohm), or bends that mess up the outer shield/braid. But you're right, if none of those are a problem, then measuring SWR before or after feedline won't matter.

Using 75 ohm feedline on a 50 ohm output would make the SWR at least 1.5 right off the bat!
05-09-2013 05:44 PM
DarrenT
Quote:
Originally Posted by Jerry Bransford View Post
So do I. Inserting the SWR meter into the connection next to the antenna just saves me from walking back & forth between the antenna & the meter.

Got tired of walking back and forth, felt like a bleeding tennis player....
Anyhow, I tested at both points and it's the same. For the price it's probably worth just buying a firestik to try.....
05-09-2013 04:40 PM
Jerry Bransford
Quote:
Originally Posted by Patrick H View Post
The last time I adjusted the antenna on the Jeep it was about 20 degrees out and windy...
I hear you & hate it when that happens here in San Diego.
05-09-2013 04:30 PM
Patrick H
Quote:
Originally Posted by Jerry Bransford View Post
So do I. Inserting the SWR meter into the connection next to the antenna just saves me from walking back & forth between the antenna & the meter.
The last time I adjusted the antenna on the Jeep it was about 20 degrees out and windy, so getting back into the warm Jeep to check the SWR was a welcome break...
05-09-2013 04:27 PM
Jerry Bransford
Quote:
Originally Posted by Patrick H View Post
Oh. I adjust the antenna, then check the SWR. Adjust again, check again.
So do I. Inserting the SWR meter into the connection next to the antenna just saves me from walking back & forth between the antenna & the meter.
05-09-2013 04:26 PM
Patrick H
Quote:
My mic cord can reach close enough to the back when I don't have a helper to key it.
Ah, there's the "key". Get it? Funny guy here...

Let the record show that I was wrong about the coax affecting SWR..
05-09-2013 04:25 PM
Patrick H
Quote:
Originally Posted by Jerry Bransford View Post
Certainly, the SWR meter can be inserted at either end for accurate results. Inserting it at the CB end though just makes it more difficult for the person tuning the antenna to see what is happening to the SWR as he adjusts the antenna length.
Oh. I adjust the antenna, then check the SWR. Adjust again, check again.
05-09-2013 04:22 PM
Jerry Bransford
Quote:
Originally Posted by Patrick H View Post
OK, if the coax doesn't affect the SWR, you can still install the meter at the radio end and get accurate results. Yes?
Certainly, the SWR meter can be inserted at either end for accurate results. Inserting it at the CB end though just makes it more difficult for the person tuning the antenna to see what is happening to the SWR as he adjusts the antenna length. My mic cord can reach close enough to the back when I don't have a helper to key it.
05-09-2013 04:21 PM
Patrick H So I have to ask....If the meter is installed at the antenna end, how do you key the mic and read the meter/ flip the switch at the same time? Long mic cord?
05-09-2013 04:19 PM
Patrick H
Quote:
Originally Posted by Jerry Bransford View Post
I hate to disagree but the coax doesn't affect the SWR on the type of antenna used on our Jeeps. I had to demonstrate that to a disbeliever years ago. I insert the SWR meter at the antenna end of the coax on my TJ for ease of adjustment and at the transmitter end of my HF ham radio antenna's coax.
OK, if the coax doesn't affect the SWR, you can still install the meter at the radio end and get accurate results. Yes?
05-09-2013 04:17 PM
Jerry Bransford I hate to disagree but the coax doesn't affect the SWR on the type of antenna used on our Jeeps. I had to demonstrate that to a disbeliever years ago. I insert the SWR meter at the antenna end of the coax on my TJ for ease of adjustment and at the transmitter end of my HF ham radio antenna's coax. If anyone ever notices a difference in SWR with varying lengths of coax with the type of antennas we use, you can blame that on having used an inexpensive SWR meter. But even when you see that, the length of the cable still won't affect the length at which the antenna is resonant to the frequency.
05-09-2013 03:37 PM
Patrick H
Quote:
Originally Posted by AC0QR View Post
When you measure SWR try to put the meter in-line as close to the *antenna* as possible. Otherwise the reading could be skewed by the type/quality/routing of the coax feed line.

Some people put the meter next to the radio, some put it next to the antenna - trying to compare readings between the two locations could result in more contradictory information!
You should hook it up at the radio end. The coax is an active component of the antenna and should be included in you SWR readings/ measurements, because the radio sees the antenna and coax as one.
05-09-2013 02:12 PM
DarrenT
Quote:
Originally Posted by AC0QR View Post
When you measure SWR try to put the meter in-line as close to the *antenna* as possible. Otherwise the reading could be skewed by the type/quality/routing of the coax feed line.

Some people put the meter next to the radio, some put it next to the antenna - trying to compare readings between the two locations could result in more contradictory information!
'Tis
I've learnt a lot from the hell of riggin up my Landy (Aluminum body).
I'm thinking maybe the whip just isn't the best tool for the job..... I've mailed firestik, see if those guys come back with suggestions (other than buy a firestik - that will be a surprise )
05-09-2013 01:59 PM
AC0QR When you measure SWR try to put the meter in-line as close to the *antenna* as possible. Otherwise the reading could be skewed by the type/quality/routing of the coax feed line.

Some people put the meter next to the radio, some put it next to the antenna - trying to compare readings between the two locations could result in more contradictory information!
05-09-2013 01:48 PM
DarrenT Freq dead centre is ch 19, which is around 2.2. Yes, I retuned it this afternoon out in the middle of nowhere and SWR on 1 is 1.9 and on 40 it`s 2.5.
Half reasonable I suppose. Now I know the high numbers are pretty much a result of reflective surfaces and lack of ideal ground plane. So I was wondering, for all of those of you which have a tail mounted antenna, what are you using antenna wise, and what SWR are you getting?
As Firestik.com list the SS64 mount (same as what I got) as their recommended mount for tub mounting...... Jeep Installations

See tub mount (#3).

Just wondering as there is some contradictory information right there.....
05-09-2013 01:20 PM
AC0QR SWR will change across freq range. It will be lowest at one freq (call it "center" freq) and increase in either direction away. You could do some trimming/tuning to get the center to be around ch 20. This might be "good enough" !

As for the SWR being overall higher than you expected: the tail light is not a great spot for a whip tuning-wise (though it is convenient & looks good - can't argue with that!).

Ideally you want a uniform ground plane below a whip, and no metal above that plane aside from the antenna itself. Obviously this is not the case here - there's the spare & mount, rollbars, and no metal plane below & behind (just the tub in "front" of the antenna).
05-09-2013 06:32 AM
DarrenT So I got the mount installed last night, it's got a good 4 point ground to the tub. Installed a new coax (GDSOB that sh*t is expensive here) and cleaned off my antenna of all the road film and crud it brought from the UK.
SWR channel 1 = 2.3, ch40 = 3.0 !!! I know I can trim the antenna some to even up the SWR deviation, but 2.3!! First key up came in at 1.6 on ch 1, then it seemed to jump for some reason (didnt change anything).
I checked all the connections for shorts, bad grounds, everything seems good. I was hoping for figures in the 1.5-1.8 region..... I thought the tub was supposed to make a good ground plane??
05-09-2013 04:16 AM
OpieDP
Quote:
Originally Posted by rusty1 View Post
I have the Teraflex mounted on the drivers side with the coax cable going through the tub behind the tail light. Plenty of room to run it through and no extra drilling.
Same here. Its very clean and was very easy. I run my coax up the grommet above the driver tail light, then up through my roll bar padding. My cb is on an arizona rocky road mount. From the roll bar I go through the mount to the cb in the middle.
05-08-2013 10:22 PM
rusty1 I have the Teraflex mounted on the drivers side with the coax cable going through the tub behind the tail light. Plenty of room to run it through and no extra drilling.
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