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 Imax 2000, to reinforce or not to reinforce?

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karelgol
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karelgol

Call Sign : 19-CT-024
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Equipment Used : Magnum 257HP,President Lincoln I, President Bill Asc, AMP-150, Imax-2000, Emperor LA-50
Age : 62

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PostSubject: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeSun Jun 06, 2021 7:32 pm

I bought a second hand imax 2000 and got a message from the seller that the top was broken just above the joint, so he let me have it for free Smile . Asking around on the dutch CB facebook group for a top section i got a lot of offers for imax antennas with the bottom section broken. This leads me to the question: Should i reinforce the joints (i've done some rodbuilding, so know a few things about fiberglass and epoxy) or would this disturb the balance of strength between top and bottom section? Anyone any advice?

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Victor
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeSun Jun 06, 2021 8:36 pm

Nice one Karel. Imax 2000, to reinforce or not to reinforce? 1f44d 

Nothing like getting something for free, especially if you can attempt a repair. Wink

I believe a few members here have the Imax 2000 so hopefully they may be able to give you a better insight.

First thoughts to broken bottom sections is that they may have firmly attached the base section to a wall or some such and oscillations further up in winds would've caused harmonic stress damage at the fixed points. (?) These type of antennas generally survive better when also mounted on a pole, the bottom pole allowing the whole antenna to sway and taking the stresses away from the fibreglass sections.

Well, that's my tuppence thoughts to it anyway. Smile

I hope you get it sorted, from what I've heard they are great antennas.


All the best,
Victor
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Bean
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeSun Jun 06, 2021 8:57 pm

Used one for years portable at 290m asl with the wind straight off the Somerset levels and not once did I ever think the joints needed strengthening , did have a phone clip once with the bottom section bent like a bannana , as Victor said failures are most likely due to incorrect installations. Dont panic about the top section doing a dance in the wind either as that takes the strain off the two lower sections ( willow and oak thing ) Only thing I ever did with mine was to redrill and fit better clamps as one snapped one freezing cold November morning (2014) whilst setting up portable.
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karelgol
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeMon Jun 07, 2021 8:52 pm

Tonight i got the second(much older) antenna. Now i've got an itchy feeling on my hands caused by fiberglass splinters. From this on i'll take the top and give it a layer of epoxy varnish. Then give all the three sections a nice new white spraypaint job. Mounting it on the telescopic mast, of which the top section is an old surfpole should be just what the doctor ordered concerning evenly distibuting the stress.
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Northern Crusader
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeFri Jun 11, 2021 2:32 pm

No need to reinforce anything. Mine is over 20 years old and managed to cope with this year's winter storms just fine sat 10 metres in the air.

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karelgol
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeSat Jun 12, 2021 12:00 pm

And it's up! Took an swr measurement with my nanoVNA from 26Mhz to 29Mhz, nowhere higher then 1.6! The lowest at about 28Mhz, 1.13!
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeSun Jun 13, 2021 2:49 pm

karelgol wrote:
And it's up! Took an swr measurement with my nanoVNA from 26Mhz to 29Mhz, nowhere higher then 1.6! The lowest at about 28Mhz, 1.13!

Well done karelgol on getting an old antenna up and running well! Hopefully you will get a good few years from it.


A5H5ATAN1C wrote:
over time not only do joints seize they also stiffen and the overall assembly looses the flexibility that stops catastrophic sheer and tear induced failures - it's never a case of 'it won't happen' just a matter of time until the inevitable.

A5H5ATAN1C, you are describing my knees well there Smile

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karelgol
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeSun Jun 13, 2021 3:16 pm

I think some are under the impression that i repaired the broken top section. I didn't. Just used 2 broken antennas (1 at the top, 1 at the bottom) to make one complete antenna. Did nothing technical, just a layer of epoxy laquer for protecting my hands from the fiberglass splinters and a spraypaint job, just for looks.
Think i'll just fiddle around with the SWR to get the dip around 27Mhz so 26.285 and 27.555 are both as good as they can get.

73

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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeWed Jun 16, 2021 10:42 pm

You absolutely do NOT want to be doing any strengthening to any section of the Imax 2000. It's ability to bend is what reduces stresses on the base section and where every section joins to the next. By strengthening a portion of it you increase stress elsewhere and risk creating a point of failure. Ideally you'd also mount it on a pole that also would have a bit of give in it rather than a thick walled steel one as this would reduce stress on the base section even more.
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karelgol
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeWed Jun 16, 2021 10:47 pm

Exactly what i was thinking based on my fishing rod building experience. Very Happy Reinforcement on one place can lead to breakage on another place.
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Alan Pilot
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitimeThu Jun 17, 2021 8:57 am

They are all made to specs that include stress and strain.
So as said no extra strengthening or it will fail at the next joint.
Aerial might look like they are just thrown together but time and money is spent designing them first.
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PostSubject: Re: Imax 2000, to reinforce or not to reinforce?   Imax 2000, to reinforce or not to reinforce? Icon_minitime

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