imax 2000 with or without?

[rockymount622]

Ok, Once again I'm asking for your knowledge. I'm putting up an Imax 2000 soon as the weather is nice and want your opinion on using the GPK ground plane with this antenna PROS and CONS... I want to talk local AND maybe a little skip but with legal power. The top of the antenna will be about 54' from the ground. Thanks in advance to all who reply! rockymount622 (North Carolina)!

 

[vkrules]

imax

In my opinion if you have the ground plane kit use it, if not I don't think it's worth the purchase price. The ground plane kit helps reduce feedline radiation and will lower angle of radiation but it adds significantly to the wind loading .I wound a choke and fitted 4 wire ground planes 8"10 long and tied them off at about a 45 degree angle. (does the same job and added advantage it also helps to guy the ant) The only downside I've seen is that my 21 mhz swr went up, most likely due to the resonant 27 mhz ground plane, other amateurs have also reported this fact .That wont affect you of course if you plan on using 27 mhz only

 

[wavrider]

As VK said it messes with the resonance of the antenna on other bands.

Google is your friend, just use search word IMAX2000 you will find many good sites with info

 

[W5LZ]

That antenna isn't resonant on any other bands! It may 'mess' with the impedance matching, but that's a completely different thing.
- 'Doc

(Put a choke under the antenna, lots cheaper than a "groundplane" that does do anything constructive.)

 

[n0zna]

it isnt worth the extra bucks with the gp kit.i have used with and without....it will tune with tuner on 10/11/12/15/17mtrs but not that great,i use a dipole for the other bands...73 de JW

 

[Happy_Hamer]

Save your money, you do not need that ground plane kit.

Buy good quality coax and connectors instead.

 

[rockymount622]

Imax 2000 without!

Thanks for all the help; I have decided to put it up without the ground plane. I didn't even consider the wind loading! 73's to all!

 

[Marconi]

In my opinion if you have the ground plane kit use it, if not I don't think it's worth the purchase price. The ground plane kit helps reduce feedline radiation and will lower angle of radiation but it adds significantly to the wind loading .I wound a choke and fitted 4 wire ground planes 8"10 long and tied them off at about a 45 degree angle. (does the same job and added advantage it also helps to guy the ant) The only downside I've seen is that my 21 mhz swr went up, most likely due to the resonant 27 mhz ground plane, other amateurs have also reported this fact .That wont affect you of course if you plan on using 27 mhz only

vkrules, we hear stories about radials making a big difference and other stories that they make no detectable difference at all. In my real world experience, I see no difference that I can detect just using my radio.

I do see adding radials tending to produce a narrower bandwidth, and maybe that is what you observed too. That suggest to me that adding slanted down radials does have some effect however.

But my Eznec Imax models do not show the primary angle to go lower when adding radials as you suggest. In fact the pattern gets much worse...at the slanted down radial angle I used. That change in pattern, due to adding radials, shows to push the 45* degree lobe out and to dominate...and it shows to become the maximum primary angle as a result.

As reported by most, that would not be too good for CB radio.

Do you have a link or anything else to support your claim?

 

[RADIOOMAN]

My two cents worth.
My friend has a Imax 2000 and I advised him to install the radial kit.
After he installed the kit he reported to me the everybody stayed the same on the S-meter, but, he was able to hear better on the weak stations because the radial kit reduced the noise level.
Might not be applicable to your situation.

 

[Mudfoot]

Sounds like you already have the GPK.

 

[Shockwave]

The matching network of the Imax is designed to work without radials. Therefore, adding them will result in a situation where there is little current on them in comparison to other "groundplanes". If one is considering purchasing an Imax and the extra expense of the GPK, just buy a Maco V-58.

 

[Justme]

Without gpk the imax will use the coax or mast it's mounted on as couterpoise, the gpk will prevent that, mine has 4 wires on the roof of 5 meters spread out, but then i use it on 17 15 12 and 10 meters.

 

[northern35s]

IF you intend to use the groundplane kit then you need to consider a couple of other actions to take, the antenna must be isolated from the mast and you must choke the coax or the groundplane won't work as it should, what we mustn't do is give the ground current any option, but to use the radial kit.


Some information worth reading:

W8JI.com end-fed vertical

And he concludes with the following

ANY END-FED ANTENNA REQUIRES A LARGE GROUNDPLANE OR OTHER EXTRAORDINARY ISOLATION METHOD OR METHODS TO PREVENT FEEDLINE OR MAST COMMON MODE CURRENTS!

In my opinion the manufacturer of such antennas relies on common mode currents for their antennas to work, the fact they will work on numerous bands without an ATU is not a good thing :blink:

 

[Justme]

The Imax is a 5/8 on 12, 11 and 10.
On 15 it's a half wave, 17 comes close to that but needs a tuner to get it from 1:2.5 to 1:1.
20 Already deminishing recieve and swr above 1:3 will be tunable and workable, but my OCF beats the cake out of it there.
A wideband coupling isn't a bad idea we do that all the time making 1:4 or 1:1 baluns working over as wide as possible frequency.
The OCF has a 1:6 and 1:1 balun in one housing and lengthened it works here for 160 - 10.

 

[W5LZ]

Justme,
Can you tell me how any non-physically adjustable antenna can be a '5/8' wave antenna on three bands? It then being a '1/2' wave antenna on another band very close to those other three has me puzzled too.
- 'Doc