Copper Talk » Ask The Tech » Antennas » Co phase two 102" whips. Is it worth it?? « Previous Next »

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Audioman
Junior Member
Username: Audioman

Post Number: 32
Registered: 2-2004
Posted on Monday, January 03, 2005 - 1:00 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I am planning to go all the way. I decided to drill holes in my truck & mount my antenna with a ball mount. I am running a mag mount K40 & want to upgrade. After thinking of getting a Wilson 1000 or 5000 I decided to do it right. Loose the mag mount & install the antenna directly to the truck. BUT, I am not sure what to do. Am i better off installing a 102" whip or should I do it all the way. Install two 102" whips co-phased on either side of the truck. I have a KIA sportage & was going to install the antennas in the both back sides of the truck.
Is it worth the effort or am I better off installing just 1 whip. For that matter should I bother installing at all or just buy a mag mount Wilson 5000 for the roof?
I have a Galaxy DX88, Texas star DX 400V, D104.
Before I take my drill to the quarter pannels I would like some suggestions...
Thanks

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Tech291
Moderator
Username: Tech291

Post Number: 28
Registered: 11-2004
Posted on Monday, January 03, 2005 - 7:39 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Audioman,to co-phase 2 whips effectivly,you need to have 1/4 wave seperation between the two.so until Kia comes out with a vehical bigger than a Hummer you dont have room to do it right.my advice is to use a roofmount of some sort,especially with the dx400.with a side mount whip,you dont want to be sitting in the path of that much rf very long.
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Audioman
Junior Member
Username: Audioman

Post Number: 34
Registered: 2-2004
Posted on Monday, January 03, 2005 - 8:24 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Very good advice.
Thank you
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Allagator
Advanced Member
Username: Allagator

Post Number: 529
Registered: 9-2002


Posted on Friday, January 07, 2005 - 6:02 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Audioman
i have a 93 S10 and im running a 102 on the rear bumper !! but i did use 3/4" 4 foot allthread then mounted a mirrior mount on the end of the allthread to get the antenna up over the camper shell !! it is directional but it works for no farther than i talk most of the time !

Hope this Helps !
Allagator
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Dx431
Advanced Member
Username: Dx431

Post Number: 968
Registered: 2-2002


Posted on Friday, January 07, 2005 - 7:35 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Try mounting the 102 in the center of the bedrail right behind the cab with a mirror mount. It's better to mount it in the middle of the vehicle than on one side.
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Chrisdey
New member
Username: Chrisdey

Post Number: 7
Registered: 1-2005
Posted on Friday, February 04, 2005 - 9:10 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Can a 102" whip be mounted to the roof or my pick up in a removable (magnetic) fashion? In other words, I use a Wilson 5000 99% of the time. I like to park on a nearby mountain and DX with my 95 T for an hour or two. Can I carry the 102" whip in the bed of my truck and mount it on the roof magnetically when I reach the sweet spot for Dx'ing on the mountain? Is the 102" that much better than the Wilson to make this effort worth it? A 102" antenna is relatively inexpensive.

A ham friend who has been at it since the 60's thinks permanently mounting a 102" in the bed or on the bumper blocks the signal. The roof is the best place so he advises me to stick with the Wilson for obvious reasons.

Obvioulsy I am new to this but I truly enjoy DX'ing and the people I meet. Thanks very much in adavnce for your opinions.

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Barracuda
Intermediate Member
Username: Barracuda

Post Number: 286
Registered: 3-2003


Posted on Friday, February 04, 2005 - 10:34 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Chrisdey,
If you only use it while stationary I would say a 102" whip on a strong mag mount on the cab would work very well, but I would also suggest finding a way to rig a good ground strap to better bond it to the vehicle to get the maximum effect from it. I would definately not use a 102" whip on a mag mount if you are moving though, not if you want to keep it anyway.
I have a 102" whip mounted on a custom mount above the rear driver's side bumper on my jeep. I use a quick disconnect to take it down when I need to. I find that it works very well in that position, but is is definately directional toward the front of the vehicle. This is very noticeable during marginal skip conditions.
73
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Kj7gs
Junior Member
Username: Kj7gs

Post Number: 12
Registered: 12-2004
Posted on Saturday, February 05, 2005 - 1:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Tech291, the ARRL Antenna Book shows 1/2-wave separation at 0° phasing for 3.8 dB gain, but only 1.1 dB gain at 1/4 wave separation which is insignificant. At 1/4-wave, best signal patterns are a result of 90° phasing resulting in a cardioid pattern, or 180° phasing firing in line with the antennas. I take it you've seen different "real-world" results?
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Tech291
Moderator
Username: Tech291

Post Number: 56
Registered: 11-2004
Posted on Saturday, February 05, 2005 - 6:53 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Kj7gs,
Yes I have experimented with co-phased whips while living with antenna restrictions.I tried different spacing,and different lengh delay lines to change the pattern.at the time i was using that setup my goal was to reject as much western traffic and make dependable 2000 mile contact to the east.all this while living where the association had antenna restrictions,no-one had cable or dish so i was limited to running strictly barefoot(12watt pep).and yes it worked!

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