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Old 09-23-2008, 04:39 PM   #1
psdnakita
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Default Diamond CR8900A

can the Diamond CR8900A be setup as a duel antenna to a Yaesu FT-8900R? i know the opion about setuping up a duel antenna system but i need it to be done because the 50" antenna will just come above my roof so i'm scared of not getting an entire 360 cover all the way around.
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Old 09-23-2008, 07:45 PM   #2
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1.) Welcome to Open Roads Radio!
2.) I have no clue.

But we have some pretty high powered nerds here and I bet one of them will have an answer for you. What exactly do you mean by "dual" ? You want to run two of them in phase? (or out of phase, depending) Any two (or more!) vertical antennas can be placed in a phased array for directivity, if that's what you want to do.

Hang tight, some one will be along with some kind of answer.
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Old 09-23-2008, 07:48 PM   #3
psdnakita
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yes in phase of each other

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Originally Posted by Radio View Post
1.) Welcome to Open Roads Radio!
2.) I have no clue.

But we have some pretty high powered nerds here and I bet one of them will have an answer for you. What exactly do you mean by "dual" ? You want to run two of them in phase? (or out of phase, depending) Any two (or more!) vertical antennas can be placed in a phased array for directivity, if that's what you want to do.

Hang tight, some one will be along with some kind of answer.
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Old 09-25-2008, 07:00 PM   #4
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psdnakita...

From your screen name I am going to assume you have a Power Stroke Deisel pickup.

That means you have a vehicle with a large metal roof that's high up off the ground. For 2m/440 amateur bands that makes a grand ground plane. For excellent omni-directional coverage at minimal cost the best solution is a 5/8 wave magmount in the middle of that roof.

Any objections to that?

If not a large pickup, then what sort pf vehicle are you putting this into?
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Old 09-25-2008, 08:45 PM   #5
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no, i have a 1983 chevy G-30 23 foot RV. thats why i need to install the antenna as a mirror mount
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Old 09-26-2008, 08:58 AM   #6
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Default Phased antennas

I don't have a lot of experience with phasing antennas. I know the length of the phasing harness is taken into consideration, depending on the band you are operating. Since you would be using multiple bands with the Diamond CR8900A that may be of concern.

You mentioned that you were attempting to get a good 360 degree radiation pattern. I think you would be defeating this purpose by phasing the antennas. If you're mounting the antennas on the outside mirrors the radiation should be minimal to the sides of the vehicle. The maximum radiation of the pattern would be to the front and rear of the vehicle. Phasing, co-phasing or using them as dual antennas, in my opinion, would not be an option when attempting to create a good 360 degree pattern.

Those Diamond antennas are top of the line antennas. I've never used the CR8900A but once ran a dual band Diamond (2 meters & 440) on the tool box of my truck with outstanding results. It was about 5 or 6 ft in length until I drove through a parking garage with it.

As "Radio" mentioned, your best bet, to achieve a good 360 pattern would be to mount one antenna. I hope this has been of some help other members may have other ideas.



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Old 09-26-2008, 09:41 AM   #7
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Your rig have a ladder? How about a short quarter wave dual bander mounted on the ladder? What are the roof and skin of the RV made of?

OCB is right, a phased arry would make a pattern shaped like an "8" with good for and aft and almost no side to side pattern. That's why truckers like dual antennas on CB, they want to hear whats ahead and behind and not much else.
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Old 09-26-2008, 12:22 PM   #8
Manual Garcia O'Kely
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The referenced antenna is not intended for mirror mounting as you will note if you read the application manual for it.

It's actually specifically designed for trunk-lid or roof mounting as it's VERY sensitive to it's ground - more so than ANY VHF/UHF antenna.

I put one on my Subaru roof and in order to match it to 10 and 6, was forced to add counterpoise wires on the roof rack to the antenna assembly to obtain an acceptable match.

I would look for another solution than this one.
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Old 09-28-2008, 04:17 PM   #9
psdnakita
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i might try to do a ladder mount, i would think putting it on the roof would make it to tall. my roof is tin and rubber roof on top of the tin.

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Your rig have a ladder? How about a short quarter wave dual bander mounted on the ladder? What are the roof and skin of the RV made of?

OCB is right, a phased arry would make a pattern shaped like an "8" with good for and aft and almost no side to side pattern. That's why truckers like dual antennas on CB, they want to hear whats ahead and behind and not much else.
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