Antenna placement

[boomer111]

So do I go with a very low SWR under 1:1:1 with the 5000 mag mount at the rear of the 4 Runner (about 4 inches from the tailgate top) or mount it center and have a 1:4:1 swr.

RUNNING A 4 PILL AMP.

I came from a Predator 10K with a 22 in. bottom shaft so the reflection was not a problem with the center location. This bottom coiled Wilson likes it front or rear of roof line. The front slopes so I picked the rear.

Probably somewhat directional now but I think I need the better tuning set up.

Long story on why the switch it is done so no need to go into details.

R=54 X with the present location. Center location and the X is in the teens.

 

[The DB]

What is R if you center it on the roof and tune X = 0?

An SWR of 1.4 is really no big deal. SWR doesn't tell you how well an antenna works, and there are cases where a higher SWR actually outperforms a lower SWR and even a perfect match. Of course the opposite can be true as well.

Knowing both X and R you seem to have access to an antenna analyzer of some sort. I suggest asking questions and learning how to use it properly. It is capable of far more than depending on such a useless figure as SWR for your tune, and honestly, if you bought it yourself, you really are wasting the money you put into it and depending on a stat that a $20 device can just as easily measure.

In the end, the location that has a lower R when X = 0 will outperform the other location. That should get you started.


The DB

 

[boomer111]

The X would not get to zero running through the band 26-28 mhz.

Ya I am sure I know nothing or very little indeed. I read the handbook and my mind just swims in place.

I should get a antenna signal strength meter just for fun.

I am concerned with getting the lowest reflection due to running the amp. The manufacturer's all suggest to keep it under 2% reflect, or about 1:3 swr. This is my primary concern.

It look better center of the roof but not sure I can live with the 1:4. The match was 95%.

I have always had my antenna with a 99% match, This was in the big rigs as well as the personal vehicle. I have seen R50 X0 many times.

I do not remember the readings specifically but they were not good enough from my past experience R 60-40 ish and the X in the teens maybe high single digit. This was across 26-28 mhz. I run the CB band even though I have an export set up. Usually stay center of the CB band.

 

[M0GVZ]

www.k0bg.com and look at the section on bonding. Make sure you do it.

 

[boomer111]

Thanks I have been over that site before. I just get dumbfounded with all the terminology.

You know that in 40 yrs of running a CB I have never performed extra grounding.

I have discovered though that with a coil antenna on the roof it is best to get the load up at least a couple of feet, while using a magnet mount anyway.

The Wilson 1000 worked real well many years ago on the center of the roof of the Honda Civic hatchback. This is why I thought I would revisit the bottom coiled antenna.

Taking hours upon hours to ground the entire car parts isn't going to happen in my lifetime.

I do appreciate the referral though.

I have never blown up an external amp or even a radio and I have owned many of both.

My swr's are always very low with excellent transmit and receive properties, with comparison to other stations.

Still not sure what I will do regarding the Wilson 5000. I may just have to give Kale a call and get a replacement coil. Then have some better ring end terminals coax made up. Ya I have made my own but not with much success. I know where to get the cable made it just having them put the correct size ends on.

Just suprised that the 5000 did not like the center roof spot. Then a 1:4 isn't the end all but while running an amp I have always wanted flat swrs.

I keep the dk at a 1-4 ratio so maybe I'll be ok with the 1:4 with the amp.

The Predator 10K with the long bottom shaft really catches tree branches.

I have been through about a half dozen.

It is nice though that the 10K stinger being shorter and thicker does not sway like the Wilson stinger does.

trade offs!

 

[222DBFL]

I had a jeep Cherokee with a single large coil monkey made mounted about 1ft from the back and it tuned good. With an mfj meter it tuned to r=50, x=0 with a 1.1 swr on channel 27.205. It was directional but I'll tell you what it worked well. And I ran more than a 4 pill amp back then. But yes it was directional with way more front than back. But for dxing it worked well while stopped or ahead of you and off to the front sides as well. Try it with the mag mount at the back for a bit and maybe see if you like it. Have a good one.

 

[boomer111]

The Wilson tunes real nice at the rear of the roof.

Just odd looking, while I am so used to center of the roof.


My reflection coefficient is .o1 flashing .02. This I like but the directional RF I will have to see how it goes. If I start to make turns and lose stations I may have to go back to the center load on the long bottom shaft. Which is a pain for many reasons.

 

[222DBFL]

You won't lose anyone in front, just some back loss. The roof of the truck provides a nice long ground plane and should do well, front and front sides.

 

[boomer111]

Ok here is my dilemma.

With the Wilson 5000 mag mount antenna I was able to get the holy grail 100% match with 1.0 swr and a reflect coefficient of over off .00. The MFJ259B even went past the -48db reading and gave me what looked like the sign of infinity. First time I have ever seen this. I always thought that 99% match and -48db with the reflection was the max.

So this is on a 96 4 Runner sitting 1 inch from the tailgate center from side to side.

Now with the reworked mag mount for the Predator 10K I have a R55 X0 with a 1:1 and 99% match but the reflection coefficient was -28db and .03. The mount is a little forward of dead center of the roof. More like center of the length of the vehicle.

I do run a 4 pill amp. I know the 10K position will give me a more reliable set up concerning my RF pattern. I really do not sit and shoot skip bit rather do it while I drive.

I really am stuck on the Wilson position and readings both pro and con. Maybe too much with both.

The other plus for the 10K is a much steadier whip with really no movement while driving. As the Wilson is dancing all over while driving.

With the Rat Shack power meter my SWR with the amp on was dead zero for the Wilson. With the 10K it was 1:2 with the amp on. Under 1.1 with it off both out of line and in line.

The Wilson reading with amp in/out and on was steady zero.

What would you all do? Between the two above scenarios.

I am not going to go the grounding route or drill.

Thanks for any feedback

 

[Robb]

boomer 111:
(or do you go by 'Crunch Dxxx' - lol?)

If you live in Campbell, CA; how come I never hear you?
You will most likely find me on 37, 38, or 39 LSB; not on AM except for talking to 'Roy' on ch 17.

I'd just put the antenna where it gets the best X value since you are using an analyzer.
Test it out in an open space away from other vehicles/objects.

'The DB' already said it right . . .

 

[boomer111]

boomer 111:
(or do you go by 'Crunch Dxxx' - lol?)

If you live in Campbell, CA; how come I never hear you?
You will most likely find me on 37, 38, or 39 LSB; not on AM except for talking to 'Roy' on ch 17.

I'd just put the antenna where it gets the best X value since you are using an analyzer.
Test it out in an open space away from other vehicles/objects.

'The DB' already said it right . . .

No I am not Crunch but we do talk. No SSB any more so strictly am.

So this would be the Wilson mounted at the very rear of the SUV roof line. Wavey whip and all.

 

[Robb]

No I am not Crunch but we do talk. No SSB any more so strictly am.

So this would be the Wilson mounted at the very rear of the SUV roof line. Wavey whip and all.

I run my mag mount where the front/rear door pillar is, but at the center point of the sheet metal roof. Otherwise, your antenna will be biased directionally to the front of the vehicle instead of being more omni-directionally oriented if mounted more twards the middle of the roof.

 

[hotrod]

I run my mag mount where the front/rear door pillar is, but at the center point of the sheet metal roof. Otherwise, your antenna will be biased directionally to the front of the vehicle instead of being more omni-directionally oriented if mounted more twards the middle of the roof.

my wilson 5k on my mini van is the same .but i talk mostly locals so i kept it center
for that reason then tuned it .heres what i got R=45 X=0. after extending the whip
i got X=0 but the R went way down.must be something about a base loaded
coil vs a centered load coil. i also had a mm and it was near perfect in center also

 

[boomer111]

my wilson 5k on my mini van is the same .but i talk mostly locals so i kept it center
for that reason then tuned it .heres what i got R=45 X=0. after extending the whip
i got X=0 but the R went way down.must be something about a base loaded
coil vs a centered load coil. i also had a mm and it was near perfect in center also

The Wilson bottom load just will not tune well in the center too much reflect (X). The Predator likes the center though but then I have a 22in. bottom shaft.

I have the 4 pill so I want the best tune location.

Funny though cause I ran a Wilson 1000 mag mount on a Honda 1500s Civic at center of the roof and it work well. Much smaller piece of metal with the Civic roof though.

Plus back then I did not have the MFJ259B.

The system like the Wilson at the very rear of the roof. Amp off and on and the swr meter needle doesn't move. R56 X0 swr 1:0 match 99 bouncing 100%

I did a test drive with both antennas and turned circles while watching incoming signal and didn't see any drop off with the antenna in the rear. Now this was with skip not a local station.

Still testing both antennas but for some reason I can not get the Predator 10K coils aligned right, they were damaged which is why I went to the Wilson.

I am pleased with the tuning of the Wilson but not with the location. I have been chasing my tail with the 10k and the coil configuration trying to get it down below 1:3 to no avail.

May have to give Kale a call to get a replacement coil. I have seen R50 X0 before with the predator in the center of the roof.

 

[hotrod]

The Wilson bottom load just will not tune well in the center too much reflect (X). The Predator likes the center though but then I have a 22in. bottom shaft.

I have the 4 pill so I want the best tune location.

Funny though cause I ran a Wilson 1000 mag mount on a Honda 1500s Civic at center of the roof and it work well. Much smaller piece of metal with the Civic roof though.

Plus back then I did not have the MFJ259B.

The system like the Wilson at the very rear of the roof. Amp off and on and the swr meter needle doesn't move. R56 X0 swr 1:0 match 99 bouncing 100%

I did a test drive with both antennas and turned circles while watching incoming signal and didn't see any drop off with the antenna in the rear. Now this was with skip not a local station.

Still testing both antennas but for some reason I can not get the Predator 10K coils aligned right, they were damaged which is why I went to the Wilson.

I am pleased with the tuning of the Wilson but not with the location. I have been chasing my tail with the 10k and the coil configuration trying to get it down below 1:3 to no avail.

May have to give Kale a call to get a replacement coil. I have seen R50 X0 before with the predator in the center of the roof.

my wilson will tune where its at but the ohms [r] is only 44 i believe. and x=0 on a
few channels where i talk mostly.yes call kale every part is suppoed to be
replaceable. id also reccommend going to a smaller shaft 17 inch for on
the roof.