View Full Version : Going mobile again

01-19-2016, 11:07 PM
Go on and cut it I double dawg dare ya!
...and done.

Mounted up in my jeep with a fender mount antenna. Getting sh#tty SWRs will post pics of antenna setup for help later. Is a front fender mount and I been trying all kinds of antenna from FS to whip w/o much success. Need more grounding and maybe a better meter?

01-20-2016, 06:55 AM
Is yours a soft top? If so try a mag mount on the hood of it. The antenna needs some metal under it to work correctly. Or try a 5ft firestick and a good mount like a Breedlove ball mount on the side or something. Just some options.

01-20-2016, 07:57 AM
yes and a 4 door so at least it's got that going for it ground plane wise :p I added a ground strap to the mount tonight and also the hood (fwiw) but didn't get to retest. continuity test gets a strong beep touching the mount and the engine block or master cylinder bracket so I think got a real good ground now. with the short whip + spring + quick disco am getting 1.7 on ch40, 1.6 ch20, 1.5 ch1 when I stopped cutting it. I think had it bottomed out in the mount too, getting tired and sloppy. tomorrow's another day though!

01-21-2016, 10:39 PM
ok guys this has been driving me nuts. mobile install fender mount on my jeep. doesn't matter if steel whip, 3' or 4' 5/8 wave FireSticks no matter what I do I get 1.6-ish on both Ch1 and Ch40, and then nearly flat match 1.1 on Ch20. Like an inverted bell shape curve. How. Why. Shouldn't the antenna be either too short or too long so one end or the other has the lowest SWR? Or was my radio tuned that way or something?

This is with my old super crappy Radio Shack meter and the antennas are all like 10 years old too. The radio is new. At this point I'm worn out twisting knobs and getting in and out of the jeep trying to get better results. Oh yeah, once I put the rubber plug on the tip then it all goes haywire and SWRS in the red! Take the plug off and everything's back to normal??? So I ain't using the plug.

01-21-2016, 10:43 PM
I have a quick disco and spring on the Fire Stick as don't know what I'm gonna' whack out there on the move. Bonus is I can hide it in the Jeep along the roll bar when not in use. Don't know if I can go with a full sized steel whip on a ball mount - will definitely need a clip to bend it down and store it for driving around in general. Thinking about it.

01-22-2016, 05:16 AM
Get a good ball mount and a good 5ft firestick. This should work just fine. And with the VSWR you have now, you should be fine to run just a radio. If you are just using the radio shack meter, you might want to invest into a 50 ohm dummy load rated at no less than 25 watts IMO. This way you can test you swr/power meter and radio before you ever install it. It will give you a baseline to go by. And you can also verify your radio and swr/power are operating correctly.
With your jeep being a soft top, I would darn sure make sure all of the vehicles body panels are bonded to frame and also bond exhaust to tie frame as well. They sell the exhaust ground strap kits with everything you need to clamp one onto the exhaust pipe and take it to a bolt that is to frame.
Again, make sure all paint is removed to bare metal and use no-ox on all connections. A side mounted ball mount at the rear left or right quarter panel would work well with a 5ft fire stick or even a 108" whip or 102" whip and an HD spring. A good ball mount is important as well. Don't skimp out and get a cheap one. It will just end up rusting. Check out Breedlove antenna mounts. Made of brass and aluminum. Quality mount.
Also. Trying a magnet mount antenna on the hood is another option as well. Place the magnet at one side of the hood and add a good antenna that isn't too heavy. The sirio performer 5000 and a sirio PL145 magnet mount would work well. They are approx 6.5ft tall. And they fold down as well. They also make a trucker style one with an 8" shaft that might fit your needs well for a side ball mount.
But before I went any further with cutting and tuning, I would first bond the heck out of the thing. Hood, fenders, exhaust, and even engine block. JMHO. You want that antenna to see your jeep as one large piece of metal rather than just a piece of it. Again, this is JMHO, but I am pretty sure it will help. Also make sure that all vehicles electrical connections are done well and that all grounds are to bare metal and have no-ox on them. If you don't know what no-ox is, here is what I am speaking of. And you want to make sure it's type special "A".
You can get this off eBay for cheap. http://uploads.tapatalk-cdn.com/20160122/f3b181cb5f49c04043eac2ccafdd3285.jpghttp://uploads.tapatalk-cdn.com/20160122/feecbc0e8a13ef47ec1d05f66c8f526f.jpg
Hope this helps and keep at it!!

01-23-2016, 04:40 AM
Awesome info! Really appreciate the education. I will get the dummy load, more ground straps and the no-ox for sure. I'm almost over the edge to actually get a 102" + a spring. Something only dreamed out since a teen. I should just do it and have my own version of Rat Patrol :) That Breedlove mount is bad ass. There's another mount that goes off the spare tire mount but it has a tall pipe to get the antenna base up and over the tire. That would keep the antenna good if I flop the jeep over accidentally on purpose. options. hmmmmm.

01-23-2016, 08:36 AM
Yep. I know the mount you speak of for the spare tire as well. Check out the Jeep forums and see what most suggest for a good antenna. Height is might, but you need some metal in the right place to make most antennas work correct. This is mobile antennas anyway. Breedlove mount you can't go wrong!! They are well made!! Have one and so do a couple of others I know. All are well built.

02-02-2016, 07:11 AM
no-ox is cosmoline? cool - useful for more than just the connectors :)

saw the Jeep pic on the Breedlove site, looks good!l

02-20-2016, 08:14 AM
Is there a way to run one of those Sirio on my existing fender mount with 3/8 hardware? Especially with a quick disco as I cannot leave it on here it will get ripped off in no time. Otherwise I will just get a 5' FS. I think my old 2' FS is burned out because it slams the meter in the red right away no matter the channel or pwr setting.

02-20-2016, 08:22 AM
I think I got the wrong Breedlove mount, seems too big to fit anywhere on the Jeep I was planning! I think there was a smaller diameter one have to check. Otherwise love the design, is totally beefy and bulletproof. got the removable antenna mount version.

First exhaust bonding clamp "kit" I found was like $25 for just one. the strap is tinned but wow pricey. gotta' be a kit with 3 clamps at a better price somewhere.

02-21-2016, 10:49 AM
Which one did you get?? I know the removable one, but how large.

02-21-2016, 11:55 PM
How long is your coax? Maybe try another piece.

02-22-2016, 06:59 AM
Also I see you clipped the clarifier to open it up to rx/tx. Which knob controls what. Is this just the coarse clarifier that is being opened up?? Never touched mine as its dead on freq on TX. No need to unlock the clarifier for me. Anyway, just curious. Thx.

02-26-2016, 09:33 PM
Am using new 18' FireRing. The white wire allows 11 Meter - I never ever go on the other channels, will be getting my ticket eventually. The Breedlove I ordered one late night is #071 with a #031 QD cap. Way too big base.

Waiting on a new 5' Firestick to arrive in meantime!

Sprung for a MFJ223 antenna analyzer trying to better see what's going on. Quite interesting!!! The graph centered on Ch20 resembles inverted bell curve - a good thing I think and backs up previous readings so I know I not going nuts. Best tuning I could get the 4' Firestick now :

Ch1 1.54 -- Ch20 1.12 -- Ch40 1.59

Was splitting hairs back and forth for at least an hour twisting the knob until I gave up :p

What I found also was the "R" factor started off 53.2 Ch1 then gradually declined throughout the band until all of sudden out toward Ch37 or so fell off the map and ended up at Ch40 R=37.6 That's resistance in ohms right?

How come did that? /me dunno but want to learn 'bout 'tennas!

02-27-2016, 03:43 AM
The antenna is a mono band antenna and will only show good VSWR and impedance where it's actually cut for or tuned for resonance. Read up on how both correlate with another and how to properly use that MFJ analyzer you have now. It will make your antenna tuning a breeze and also teach you to tune for good impedance match and not just VSWR as now you see there is more than just VSWR involved with proper tuning of an antenna. JMHO. Read up on the analyzer you got also read the Manual to learn how to use it the right way!! Again, JMHO. Tune to R=50ohms and X=0 at the freq you want the antenna to be resonant at. Since you are using a 50ohm impedance radio, coax, and antenna, you need to have them all be as close to 50ohms as you can with X=0 or as close to 0 as you can get.

02-27-2016, 05:57 AM
this is all new to me but I'm trying to learn! found this webpage and has really good info to start. I need more instruction or info on all this matching and coil stuff. I think I got an old antenna book around here somewhere. For sure a book on the technician license that I started to read then put down :(


please note X already = 0 at Ch20 (pic attached) I know this is just a rebranded china meter. the manual doesn't go into the background info or theory or anything and is printed in font so small it makes everyone look chinese just reading it :) the firestick antenna paper didn't either. first time I've heard about this X factor! How does one tune to R=50? is this where a ferrite thing comes into play or something?


02-27-2016, 06:01 AM
oh yeah, the tub of no-ox came in the mail too!

02-27-2016, 06:06 AM

02-27-2016, 06:13 AM
I need to make a choke near the fender mount?

02-27-2016, 06:15 AM
resistance is too high leading to a "fake" low SWR? how would I get to 50 ohms? is the cable bad? wow, questions!

02-27-2016, 11:15 AM
No. Read up on how to properly use your meter. You need to tune antenna as close to feedpoint as possible. 1ft coax jumper or less, or even a barrel connector and go direct to feed point (connector) of antenna. Or you'll need to use a 1/2 wave electrically tuned coax jumper. Here is the formula to do this as IDK what coax you are using and the Velocity Factor (VF), will be needed to make it the right length.
492xVF/freq (in MHZ).
So for example. Your coax is .85 VF.
492x .85/ 27.205= 15.55ft coax jumper needed to tune antenna at 27.205MHz. Now that I have confused the shit out of you LOL, don't worry it did me too, take this formula and use it to tune your antenna the proper way using your antenna analyzer. Then once this is done, you can use whatever length of the same coax you want and the reading should be the same as when you tuned the antenna as now your antenna system if done correctly is at 50ohms. And you will have the correct VSWR readings as well as R and X. Good luck and keep reading, the more you learn about your antenna analyzer and how to use it, you'll enjoy tuning antennas and it will be a breeze!! Hope this info helps!! Have fun!!

02-27-2016, 11:18 AM
Read up on how to really use your meter. There is a lot of good stuff on that analyzer if you know how to use it the right way. Took me a while to get it, but once you see the light, things get very clear!!

02-27-2016, 04:54 PM
I get the gist but think I need to take a class or something. Going to get this book:
Antenna Physics: An Introduction

changed my mind, going to buy the Basic Antennas book by Joel R. Harris W1ZR as more my speed (?)

This book will provide a foundation in antenna theory and design necessary for anyone undertaking more advanced topics such as those presented in The ARRL Antenna Book (http://www.arrl.org/shop/ARRL-Antenna-Book-22nd-Edition).

Dipole Antennas
Antenna Impedance
Transmission Lines
Practical Two Element Arrays
Wideband and Multiband Antennas
Reflector Antennas
Yagis for HF and VHF
Loop Antennas
Antennas for Microwave Applications
Vehicle Antennas
Antenna Measurements

Plus, an Introduction to Antenna Modeling...and much more!

and because I'm struggling searching this stuff online found this one: Understanding your antenna analyzer

02-27-2016, 05:02 PM
feels like going down the rabbit hole hahaha! but know what I have currently is at best one size fits all. guess I could write the mfr to get the VF on the firering cabling? but say do the math and get the dimension. wouldn't that only apply in theory as it would change when actually installed and running around the vehicle through the firewall plus whatever other external influences?

good stuff though. I like to understand what's going on :) best I can at least. mind starting to get blown though on all this smith formula, reactance, funny looking math symbols and all that. :p

02-27-2016, 05:53 PM
Ask Dave!


02-28-2016, 12:21 AM
Nope, should not. And here is a good read as well.


02-28-2016, 12:24 AM
And also Walter Maxwell's book named "Reflections" published by the ARRL. Another good read.