IMAX 2000 Question ?

[EMS-1]

I have an IMAX 2000 fiberglass CB antenna that was taken off a tower almost 80 feet tall. I have discovered after getting it down the top (3rd) section is missing and had been apparently for a while. So my question is: How did they, or is it even possible to use/transmit on this antenna without the top section?. I would like to use it, but not until I know for sure it will work. Any ideas?.

 

[LtDoc]

If it were mine I wouldn't use it. If a third of it is missing then it's a fairly sure bet that it isn't going to be close to 'right'. Could it be used for transmitting? Yes it could, but not with any expectation of it being a good antenna, or even marginal. They ever put a meter on it? Then again, maybe that's why it's not still up on that tower.
- 'Doc

 

[EMS-1]

Thanks...I don't think they ever metered it because the old CB'er passed away long before the tower came down.

 

[RevGary]

The top section of an IMAX 2000 .64 wave antenna is 96.5 inches in length. IF you can find an Antron/Solarcon A-99 top section, which is 72 inches long, the chrome threaded portion is the same. By using an in-line antenna matcher to get the SWR that the radio sees down to less than 1.5 to 1, it will work fairly well that way. Of course, the best way to do the repair would be to get ahold of a new IMAX 2000 96.5 inch top section.

Did the top section fiberglass break off - leaving the chrome threaded portion inside the second section ?

 

[SCPD]

Imax2000

I would look at truck stops for a fiberglass whip 6ft. long. Not a firestick with wire around it under the plastic. I had a A99 with the same problem it came down in a storm and broke the top section . I found a white fiberglass antenna at a truckstop and it worked great after that.

 

[ill41]

I had a I-Max 2000and the top broke off.I replaced it with a 102" stainless steel whip.The SWR's were completely flat on the band.The noise level was also quiter with this set-up.

 

[kb2vxa]

Oh dear, here we go again with a load of misinformation!

Bottom section: 80 inches
Middle section: 94 inches
Top section: 96.5 inches
That makes the total radiating element length 270.5 inches.

Take it from someone who dissected one and examined the guts, he knows what he's talking about.
The Imax 2000 EXPOSED!

Getting straight to the answer, the missing section is 96.5" and no substitute will work properly. What tends to be most misunderstood is a short fiberglass mobile CB antenna is electrically a quarter wave or 102" which would make the entire antenna too long. To keep it short and simple, the end result would be an impedance mismatch and high SWR.

"Oh, SWR doesn't matter on receive." There's much more to this than SWR alone but a course in antenna theory we don't need here, just take my word, it won't work as intended.

 

[SCPD]

Imax 2000

read this then I will let you decide. 102 " Whip On Imax 2000 [Archive] - QRZ Forums

 

[kb2vxa]

Go back and re-read the last line of my post above.

"There is no performance gain or loss."

I have to laugh, no way did he take field measurements at an antenna test range with proper instrumentation or analysis so how does he substantiate that statement? QRZ is more than a joke, it's a laugh factory. I stand by my statement because a .64 wavelength antenna's (or any other) vertical radiation pattern which determines gain will change considerably when wavelength is increased.

 

[LtDoc]

Sorry, but there are so many 'half-truths'/goofs in that "Exposed" article that if you don't know what you are talking about, it's just not very informative/truthful. Comparing 'dBi' and dBd' is just one of them, there is no direct comparison.
TOAs or take off angles. Only low ones are useful/desirable? Just not so. High ones are always wasted? Also just not so. How do you know which ones you should have? You can't know, at least not without equipment/information even the antenna test ranges don't usually have. Generalities are never more than 50% accurate at best. What's exposed most in most "Exposed" type articles is the bias of the author. That's the case with this one too...
- 'Doc

 

[kb2vxa]

"This could also be stated as 0.8 dBd gain."

I see you misunderstood the author's statement, nowhere did he make any comparison of dBi to dBd, rather he said they could be stated two ways. I'm sure you know manufacturers use the dBi mathematical construct rather than the dipole (dBd) real world standard to inflate the figures.

Let's not get picky here, generally speaking putting more signal to the radio horizon is most desirable, we're not talking space communications here, this is CB. I don't see any bias by the author for the above reason. Anyway, I never intended for a technical discussion that surely would go over the heads of most users of this board, casual listeners haven't the need for such.

 

[EMS-1]

Thanks for the replies guys, I guess the IMAX will get scrapped and I will keep using the 5/8 I have up.

 

[kb2vxa]

May as well, the Imax wouldn't be all that much of an improvement. What I haven't mentioned until now having been in an electrical entanglement is the top section is missing for a good reason. Look at how long it is altogether, an unsupported, whopping 22 1/2 feet! All well and good for a flagpole which is a larger diameter and much stronger, the wind just ate it for breakfast.

Before you scrap it you may consider another use for it. Beating dead horses is a popular sport around here. (;->)

 

[swen_out_west]

I had a I-Max 2000and the top broke off.I replaced it with a 102" stainless steel whip.The SWR's were completely flat on the band.The noise level was also quiter with this set-up.

Sorry to resurrect this 5 year old thread, but I have the same issue. Not sure if this member is even still around or not.

Has anyone tried this and how did it hold up?

I am going to try to contact Solarcon and see if it's possible to purchase just the top section.

My IMax 2000 worked good for me, so let's try to keep the negative comments regarding an IMax 2000 to a minimum.

If not I have a brand new Penetrator 500 I am putting up anyways, in fact we wouldn't have broke it if I had kept it up. I just would like to repair it as a secondary.backup antenna.

 

[swen_out_west]

I am also assuming that he trimmed the excess off making it 96.5 inches and the same overall length.

 

[swen_out_west]

I am also assuming that he trimmed the excess off making it 96.5 inches and the same overall length.

Actually just got done looking at the spec sheet. Correction: 95.5. There's always the tuning collar to get it a good match.

 

[Dude111]

I had a I-Max 2000 and the top broke off.I replaced it with a 102" stainless steel whip.The SWR's were completely flat on the band.The noise level was also quiter with this set-up.

Thank you..... My top part of my IMAX came down also in a wind storm one day (The whip)


Good luck swen_out_west and EMS-1 I hope you have a new setup by now

 

[TheSpaceMann]

Thanks for the replies guys, I guess the IMAX will get scrapped and I will keep using the 5/8 I have up.

Contact the manufacturer to see if you can get a replacement top piece.

 

[swen_out_west]

Guys. Just to let you know. There's a 5 year gap from when I resurrected this thread the other night and it looks like most of the people are not active users anymore.

The answer to SpaceMann is by the time I found the number and tried calling on Friday it was too late .

As for Dude111 I have a 102" whip on the way from Amazon Prime and will be here Tuesday Morning. I am actually going to try the fix next weekend and get back to you. Going to start with not trimming it and seeing what it reads on my meter, since I would still like to have a 102" whip, but anything obver 1.25 is going to get trimmed. Actually looking to test to see how much static it drops. Considering that I live right by a major high line going to the next city 60 miles north, a large transformer sub station, and a Tesla Charging Station I get alot of static.

But I did jump the gun. The way it whipped into the ground shattered the top one foot. I taped it up and stuck it up 20 feet. It doesn't have 1.02 VSWR anymore, but I'll take 1.2.

 

[Dude111]

Well I hope things go good!!!