Exceptional Performance for a Tri-Bander and More! Time Owned: 6 to 12 months. I installed the Cushcraft X-7 about 8 months ago and have now had enough time with it to make what I think is an honest opinion and performance observation based on my type of amateur operation. My main focus is DX and contesting.
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Exceptional Performance for a Tri-Bander and More! Time Owned: 6 to 12 months. I installed the Cushcraft X-7 about 8 months ago and have now had enough time with it to make what I think is an honest opinion and performance observation based on my type of amateur operation.
My main focus is DX and contesting. For about 20 years prior to the X-7, I used a Cushcraft A-4 and, yes, though I had to rebuild the traps and replace all of the original hardware with stainless steel, the antenna worked very well. I have also used other various antennas including mono-band beams and tri-band yagis during my many years of this wonderful hobby. The bottom line is the X-7 is a superb performer! For its 18 foot boom length, low wind load, and mechanical strength which was very important to me in my storm-prone QTH I think it is one of the best antennas on the market today.
My antenna is installed at 52 feet on Rohn 45G tower. I would put it up against any antenna in its class, including mono-banders. The Cushcraft design team got this one right. Their mission was to redesign the original A-4 tri-bander while maintaining its reasonable 18 foot boom length.
Their use of the log periodic cell for the driven element and losing the traps in the driven and reflector elements of the A-4 seems to me to have changed a good antenna into a exceptional high performance antenna. There are still traps in the director, but this is a low current area of the antenna and trap loss is minimal. The input impedance of the antenna is ohms so a ferrite balun is used to provide a 50 ohm match.
The SWR across 20, 15 and 10 meters is great and by using the log periodic cell driven element the antenna is useable with forward gain and with very acceptable SWR on the upper WARC bands 17 and 12 meters. My SWR on 17 meters is approximately 1.
There are some things you need to pay very close attention to during construction of this antenna if you want the good performance. Take your time, measure everything twice, then measure it again. This is not an entry level project! There are over pieces of various screws, bolts, aluminum and other parts that have to go together. It is a complex antenna and took three experienced hams two full days to construct it.
Several people have said that they had had trouble with the ferrite balun and subsequently found loose connections inside when they opened it up. I highly suggest that before final assembly you take the cover off the balun and check the hardware. We did that with mine and found that it was good, all hardware was tight as it should be. As with any antenna project you will also want to check and re-tighten, if necessary, all of the SS clamps, bolts, etc. This will take additional time, but you will be glad you did it.
And, as I have on all of my antenna projects over the years, I spayed all the various bolts and screws with clear enamel to keep water out of the antenna as much as possible.
There is one big potential "gotcha" that is easily missed and is not discussed in the instruction manual Cushcraft, me and my assembly team believe that you need to address this!
The flat aluminum straps that make up the feed system assembly come out of the box with a thin clear plastic film tape covering on them. You cannot see this film and it can cause you a major headache if it is not removed! None of us noticed this covering during construction. A week or so after the assembly weekend, and luckily while the antenna was on the ground on saw horses, I was inspecting it and re-tightening things when I noticed what looked like a small bulge of something on one side of the crisscross feed system.
On further inspection I saw the thin film starting to peel. I had to remove the entire feed system to get all of the tape off. Some people have complained that for no reason their SWR would go high and their X-7 would not perform correctly. Wonder why? Once you put this antenna together correctly and get it a reasonable height above ground, you will be amazed at its performance.
You will not wait in many pile ups! I hope this review is helpful. I love this antenna! Good DX!
Cushcraft X-7 SWR Problems...
I have seen two things. I convinced him the X7 is really good antenna and would get out of literally the Hole he is now cushcratf in. I took plenty of time for assembly; this is a large tribander with lots of pieces. Just traps from one element was used back We had some very heavy wind conditions the last month with gusting over 80Mph.
Cushcraft HF Beam Antennas X7
Vudobei This antenna just flies in the wind, no damage done. Here are some pictures! Performance is just as advertised, based on observed beamwidth, front-to-back and VSWR curves. What we found when I took the cover off!! I bring my antenna array to the ground level a few times a year to do preventitive maintenance on them. I get a real good swr on the bands the antenna is designed for Inside My Radio Room.
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