MP-33-N-WARC Review
I recently decided to put up a beam. Since I am subject to CC&Rs which prohibit any “unsightly antennas and supports” a small beam with minimum visual impact was a must. I also wanted a 5 band solution. Since the beam had to be mounted on a push up mast, I selected the Mosley MP-33-N-WARC since it is very lightweight, has a slim profile, and has a 12 foot boom all while offering reasonable performance.
The Cushcraft A3S and A4S were considered and rejected because they were not 5 band antennas and the boom on the A4S was too long. The Hy-Gain Explorer 14 (which is an excellent antenna I used to have and loved) was also rejected, primarily because it was not a 5 band antenna. My XYL rejected the Hex Beam because she objected to its appearance. I considered the SteppIR 2 element beam, since it too operates on 5 bands, but I wanted an antenna that was automatic band switching, and needed no mechanical maintenance. I looked at the gain figures for the SteppIR 2 element and the Force 12 C3 and C3S and concluded that a well designed 3 element trapped antenna on a 12 foot boom would have more gain, a better F/B ratio, and better pattern than a beam with 2 full size elements on a much shorter boom, or the same gain as a two element full size antenna on a 12 foot boom.
I ordered the MP-33 antenna, which Mosley made to order, so I had a 30 day wait. During that time, I had a number of technical questions for the folks at Mosley and could always get through to a Tech who was happy to answer any questions I had. Initially, I ordered the 30 meter add on kit, but when I read the manual (which Mosley was happy to email) I realized it would have too much visual impact. Mosley adjusted my order and gave me a credit without any hassle. I also called Mosley and asked them if they could expedite my order so the antenna could be up for the ARRL CW DX Contest. They move the delivery date up a week as requested. Their customer service gets a 5.
When the antenna arrived, it was packed well and the elements pieces grouped together. Assembly was a snap since everything was color coded and the elements are pre-drilled, so there was no measuring. Simply select the CW or Phone setting and you are good to go. I have assembled a large number of antennas over the years, including several large beams, and this antenna was, by far, the easiest to put together. It’s almost impossible to put the beam together incorrectly. It took almost exactly 4 hours (without rushing) get the antenna mounted on the mast from the time the Federal Express delivered the antenna. The manual was very clear and the pictures helped in the assembly process. The quality of the antenna, from mechanical standpoint, is outstanding. Robust, yet lightweight. It looks like it will last forever. Physical quality also gets a 5.
Now, to performance. I’m not going to talk about the SWR, because that is no way to evaluate an antenna. My dummy load is a perfect match for my coax. I’m also not going to compare the beam, based on vague memories, to any of the other antennas I “used to have”, because you really can’t do a meaningful evaluation unless you can do repeated A/B tests over an extended period of time. Instead, I used the Reverse Beacon Network (amazing resource) to eliminate as much subjectivity as possible. I measured the F/B and F/S ratios on a number of bands over several weeks under varying propagation conditions. Using the Reverse Beacon Network I also compared the MP-33 to my SteppIR BigIR Vertical which, as verticals go, is about the best there is. The base is mounted at 25 feet and it has 7 resonant radials for each band. The beam, for now, is also mounted at 25 feet.
I’ll admit the MP-33 is a bit low, at 25 feet, for a low take off angle on 20 meters and would perform better at a greater height. I’ll run these tests again when I get the antenna up to about 30 feet, but even that height is far from optimum on 20 meters. I miss the tower I had at my prior QTH!
The A/B results for forward gain (minimum number of tests for each band was 25) are listed below. The beam may not have been pointed directly at the RBN station in all cases so the gain may actually be higher. I did notice that turning the beam only 30 degrees made a big difference in the signal strength in some cases.
On 20 meters, the improvement was between 0 and 10 db, and averaged 5 db in favor of the MP-33.
On 17 meters, the improvement was between -1 and 14 db, and averaged 5.6 db in favor of the MP-33.
On 15 meters, the improvement was between 0 and 14 db, and averaged 6 db in favor of the MP-33.
On 12 meters, the improvement was between 1 and 14 db, and averaged 6 in favor of the MP-33.
On 10 meters, the improvement was between 1 and 9 db, and averaged 4.6 db in favor of the MP-33.
As noted above, I also confirmed via repeated A/B testing, that the MP-33 has some gain and F/B ratio on both 17 and 12 meters despite being a dipole on those bands and, of course, a reasonable F/S ratio. A call to Mosley confirmed my conclusion. The Tech commented that “you are not the first MP-33 owner to say that”. This is due to the proximity of the WARC dipole to the driven element for 10/15/20, resulting in signal enhancement. Compared to the vertical, the signal improvement was approximately 5-6 db as measured repeatedly on the RBN, sometimes more. I am very pleased to have so much improvement on the WARC bands compared to the vertical, despite it being “only a dipole”. As Tom Shiller, founder of Force 12 Antennas, once said “A dipole is a great antenna and can often give substantial improvement over a vertical when mounted at the correct height.”
I’ll admit I am very surprised the WARC dipole compares so favorably to the 3 element tribander!
While I don’t have the ability to compare the MP-33 to any other beam on an A/B basis, I have confirmed it is a very substantial improvement over what I consider to be the best multi-band vertical antenna on the market. That antenna, in turn was also a very substantial improvement over the Hy-Gain DX-77 Vertical it replaced. The MP-33 has significant gain over the SteppIR vertical – as one would expect - and respectable F/S and F/B ratios. I can hear signals clearly on the beam that are buried in the noise on the vertical. Performance also gets a 5. It was an upgrade well worth making. Might another beam have performed better? Maybe, but I am very pleased with the antenna which is performing well despite it’s low height and small size.
73 es good dx,
Bob/AA6VB
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