Base New Imax wont tune 11m....this sucks

[Marconi]

In part, I take away from this current thread that the Imax has been made shorter in length, and now the New Imax will not work with a really low SWR in the CB band like the original. This puzzled me a bit at first but to be fair I'm still guessing a bit.

Some of my old CB buddies that were also Ham operators and had the Imax claimed they used it on 10 meters and did not require a tuner or trimming.

I found an old bandwidth curve I posted in the PDF file below. It was in my antenna notes that I made in 2009. It was for an Imax at 49' to the tip. I used my Kenwood TS 50 so I could see beyond the CB band. It shows me the lowest SWR at 27.505 Mhz. From there was a rise to <2.00:1 SWR at 29.305 MHz on the high end.

I only went down on the low side to 25.205 Mhz. Going down in frequency the Imax shows a trend going down to 25.705 MHz close to 1.40 SWR. Unfortunately that is as far down in frequency as I went. With this incomplete BW...the span shows to be 3.6 MHz wide. So, the original Imax may have had its peak on the high end about 29.305 MHz and a very long span lower in frequency on the lower end. How far out I don't know but I've read it will work at 15 meter with some tuning maybe.

Back in the days, before I was able to check frequencies well above and below CB...I saw a flat SWR BW curve for both the Imax and A99, but all of those records are lost.

I used the forum search function and entered "Imax Bandwidth." I found discussions where the Imax and the band width was being discussed. Some said it was broad and others said it was just normal.

https://www.worldwidedx.com/threads/imax-very-large-bandwidth.17457/

https://www.worldwidedx.com/threads/imax-2000-from-palco.32406/#post-130438

SWR ON A IMAX 2000

SWR ON A IMAX 2000

better antenna

I wonder if the New Imax, supposedly working better on 10 meters now, will still work multi-band like we hear some Hams claim?

Here is my original bandwidth curve for the Imax, possibly suggesting a long flat curve lower in frequency than CB and the high end peak near the top of 10 meters.

Sorry the PDF file is in landscape mode and does not copy very well. Maybe you can see the trend the curve might be suggesting however. If you need to get a closer look use the Zoom feature in the PDF file.

 

[Marconi]

Here are 10 pages of ham reviews on the eHam website that might be of interest to some.

I was not required to login either.

https://www.eham.net/reviews/view-product?id=1376&page=2&per-page=10

 

[KD2GOE]

I took mine down to fix it.. i never cut any thing off it
i am cleaning it up and Painted it with UV resistant Lacquer.. the Fiber glass was turning to dust..
oh i looked back when i got it it was back in 2014

 

[Marconi]

KD2GOE, those dimensions are the same as I posted above for my IMax.

When you get it fixed and back up, and if you have an analyzer, could you check and report your <2.00:1 SWR bandwidth from one end of the BW frequencies to the other?

Good luck on your repairs and keep us posted.

 

[KD2GOE]

KD2GOE, those dimensions are the same as I posted above for my IMax.

When you get it fixed and back up, and if you have an analyzer, could you check and report your <2.00:1 SWR bandwidth from one end of the BW frequencies to the other?

Good luck on your repairs and keep us posted.

Yes I do and I will

 

[Marconi]

Thanks.

 

[KD2GOE]

With my MFJ-266
1.5:1 @ 27.100 TO 29.000 Mhz
1.1:1 @ 28.200
With my Kenwood TS-2000 meter
1.5:1 @ 25.730 to 29.900mhz

1.5:1 @ 22.9Mhz 20.45

rings 5/8 up

 

[Marconi]

Took my old Imax down today and put up a new one.
right at factory its 2-1 on 26.965, 1.6 on 27.405 and 1.35 on about 28.000 then shoots up after that.
I put the rings in the middle and got 1.05 on 28.485 but 27.385 sucked.

Just love spending $200 and risking my life for a piece of junk...
View attachment 23375 View attachment 23376 View attachment 23377

Unreal. gonna climb up and try the rings low but I know its gonna be crap.

** I put the rings about 1/2 inch from the bottom.
Best swr is 1.47 at 27.780, 1.56 at 27.385 then its 2.0 at about 26.200.
fricking garbage

With my MFJ-266
1.5:1 @ 27.100 TO 29.000 Mhz
1.1:1 @ 28.200
With my Kenwood TS-2000 meter
1.5:1 @ 25.730 to 29.900mhz

1.5:1 @ 22.9Mhz 20.45

rings 5/8 up

Thanks to both of you for reporting your bandwidth info. They're not the same, but they're close enough for me to see the trends toward lower frequencies.

Thanks KD2GOE. If I'm reading your numbers right, in part for your <2.00:1 SWR bandwidth is over 7 MHz at 22.900 to 29.900 MHz. A bit wider that I thought, but with a long feed line we might expect to see more bandwidth.

What does the last value, 20.45, mean?

Don't worry about about checking this anymore for me, I see enough in the trends for the curve to know the New IMax is also very broadbanded down in frequency. This confirms what Ham operators report when they claim the IMax works very well in several of the higher HF ham bands including 10 meters.

 

[KD2GOE]

Thanks to both of you for reporting your bandwidth info. They're not the same, but they're close enough for me to see the trends toward lower frequencies.

Thanks KD2GOE. If I'm reading your numbers right, in part for your <2.00:1 SWR bandwidth is over 7 MHz at 22.900 to 29.900 MHz. A bit wider that I thought, but with a long feed line we might expect to see more bandwidth.

What does the last value, 20.45, mean?

Don't worry about about checking this anymore for me, I see enough in the trends for the curve to know the New IMax is also very broadbanded down in frequency. This confirms what Ham operators report when they claim the IMax works very well in several of the higher HF ham bands including 10 meters.

oh the 20.45 is Mhz i was scanning for a dip and forgot to take that out of the post lol opps

I have a 100 foot run of Davis RF BURY-FLEX running underground. it's like LMR 400 with a stranded copper core.

this is the small tower i have it on..

 

[Marconi]

OK KD2GOE.

I suspect most folks consider the reported <2.00:1 SWR bandwidth as somewhat irrelevant.

I use the reported <2.00:1 SWR BW as a gauge for the accuracy of some of my Eznec models, and for sure with models that show a naturally good match, and thus they report a good low SWR...just by entering the accurate antenna dimensions into Eznec. No matching required in these cases.

Or, if I need to try and match a model that doesn't naturally show a good match, and doesn't report a BW close to the manufactures reported BW...then I consider the model is not likely to be accurate.

This is why I sometimes seem to "beat a dead dog" asking questions about the <2.00:1 SWR bandwidth.

Thanks for the help!

 

[357]

I just put a SS 102" whip on. Might of helped a tiny bit but it still sucks.
I put the rings, 1 top, 1 bottim to get 1.3 on 38.
Gonna throw it back up and see what I get though the coax.
I'm super pissed

 

[Recon]

I just put a SS 102" whip on. Might of helped a tiny bit but it still sucks.
I put the rings, 1 top, 1 bottim to get 1.3 on 38.
Gonna throw it back up and see what I get though the coax.
I'm super pissed

Good luck with splitting the rings. The rings are in pairs so as to lock against each other. The thread pitch of the rings and mast are "sloppy" and I doubt that a single ring will stay in place by itself.
Just a suggestion. Maybe you should consider drilling and tapping a 8-32 or 10-32 thread horizontally in the ring and install a 8-32 or 10-32 stainless set-screw to keep the ring from vibrating up or down the mast before you burn-up more time and labor.

 

[357]

The 102" whip made the swr worse.
This thing is done. I put the factory whip back on.


This isn't the Imax I remember. I dont know what they did but its the 35th time I've had this thing down.
A flat match on any frequency is impossible except like 23mhz.
Even with a 1.35 swr people cant hear me. at 1.5 with the rings somewhere else it seems to get out better.

My buddy has one and its a flat match on 40 and 1.1 on ch 1.
Another guy has a antron 99 with a flat match across the band.

This horse is dead.

Heres some measurements from the bottom of the mounting plate, and a cheap plastic insulator thats seen better days.

total length with 102 whip: 291.5"
total with stock whip: 285.5" 23.79 feet

Expected lengh: 289" 24.08 feet

 

[Recon]

The 102" whip made the swr worse.
This thing is done. I put the factory whip back on.


This isn't the Imax I remember. I dont know what they did but its the 35th time I've had this thing down.
A flat match on any frequency is impossible except like 23mhz.
Even with a 1.35 swr people cant hear me. at 1.5 with the rings somewhere else it seems to get out better.

My buddy has one and its a flat match on 40 and 1.1 on ch 1.
Another guy has a antron 99 with a flat match across the band.

This horse is dead.

Heres some measurements from the bottom of the mounting plate, and a cheap plastic insulator thats seen better days.

total length with 102 whip: 291.5"
total with stock whip: 285.5" 23.79 feet

Expected lengh: 289" 24.08 feet



View attachment 32840 View attachment 32841 View attachment 32842 View attachment 32843 View attachment 32844 View attachment 32845 View attachment 32846

The last photo shows a horizontal mark / line on the mounting plate which indicates the mast / pipe was attached to the wrong side of the plate.
I'm no antenna guru and I am probably way off base, but if the mast / pipe protruded beyond the mounting plate and was close to the tuning rings, maybe the mast / pipe interfered with the SWR. Experts please chime in.
There is definitely an issue with the total length with your antenna because my MAX 2000 is exactly twenty-four feet long. Don't give-up yet. Maybe if you trim-off the top of the stainless whip to obtain a total length of twenty-four feet, the SWR would be within the specs.

 

[Recon]

The 102" whip made the swr worse.
This thing is done. I put the factory whip back on.


This isn't the Imax I remember. I dont know what they did but its the 35th time I've had this thing down.
A flat match on any frequency is impossible except like 23mhz.
Even with a 1.35 swr people cant hear me. at 1.5 with the rings somewhere else it seems to get out better.

My buddy has one and its a flat match on 40 and 1.1 on ch 1.
Another guy has a antron 99 with a flat match across the band.

This horse is dead.

Heres some measurements from the bottom of the mounting plate, and a cheap plastic insulator thats seen better days.

total length with 102 whip: 291.5"
total with stock whip: 285.5" 23.79 feet

Expected lengh: 289" 24.08 feet



View attachment 32840 View attachment 32841 View attachment 32842 View attachment 32843 View attachment 32844 View attachment 32845 View attachment 32846

You have nothing to lose buy trimming the 102" whip with a Dremel cutting wheel and re-set both tuning rings to about 1/4" below the middle of the threads. Go for it!