Cushcraft MA5VA vs. Solarcon I-MAX 2000?

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KB2GOM

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prcguy

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I had a MA5VA for awhile and it didn't work very well on any band. At the time I had a home made broad band T2FD that was 165ft long at my office between two parking lot light posts. A T2FD is a lossy folded dipole with 12:1 transformer at the feed point and a load resistor around 800 ohms opposite the transformer on the folded end. On its lowest band it has about 5dB less gain than a resonant 1/2 wave dipole of similar size and at the same height.

I came across an MA5VA used for a good price and thought it would supplement the T2FD on the higher bands since that was mounted about 25ft horizontal and considered a "cloud burner" for NVIS on the lower bands. Wrong. On every band 20 through 10m and even for local ground wave chit chat, the T2FD worked better than the MA5VA.

I later replaced the T2FD with a ZS6BKW and that worked a bit better but needed a tuner. Bottom line is the MA5VA is a dog, it appears to be a shortened 1/4 wave stub tuned vertical over a small and inadequate ground plane.

I build a friend a great performing 17/20m antenna starting with a typical 64:1 transformer you would build for a 40-10m EFHW but used a 17m trap and just enough wire to resonate it on 20m and 17m. Its about 24ft long and he uses it portable off a 20ft telescoping mast with the end guy rope tied to a fence. You could run this vertical with a fiberglass telescoping mast and it would work great. Or forget the trap and make it 26ft long for a mono band 17m or about 32ft long as a 20m or about 16ft long as a 10m only. The 20m version would also resonate on 10m but if its vertical the 10m lobe would be way up in the air and down at the ground and not very useful.
 
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alcahuete

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It has been a while since I have used the Imax, but it definitely works on those bands, even down to 20m without the ground plane kit.
 

vagrant

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My Imax works best on 15m, next is 10m, next is 17m. It sucks on 12m. I don’t have the ground plane kit. I mainly used it on 15 and 10, but my SWR of late is bad. I may try the Diamond 10/6 vertical next.
 

vagrant

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Currently, the base of the antenna is at 38’ AGL. I have used it as low as 16’ AGL and heights in between. I’ve made contacts on 10 meters to every continent except Antartica. On 15m I would typically find a Japan station. Their setup was doing the work.

I‘ve had it almost 10 years and I use it for local 10m weekly nets as well. A group of us used to chat almost daily on 10m. I now use a K4KIO hexbeam for distant stations.
 
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