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Reviews Categories | Antennas: VHF/UHF+ Directional (Yagi, quad, etc.) | M2 2M4 Help


Reviews Summary for M2 2M4
Reviews: 2 Average rating: 5.0/5 MSRP: $129.99
Description: 4 Element, 144 to 148 MHz
Product is in production.
More info: http://www.m2inc.com
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VK2ACD Rating: 5/5 Nov 10, 2014 23:15 Send this review to a friend
Top quality  Time owned: 6 to 12 months
Pretty much standard performance for 4 elements, but has excellent design and build. Fully sealed and uses N connectors, which should be on all VHF gear.
A slow assembly using the S/S washers and I didnt like the way they scratch the element rods when fitting, but I guess its designed for once only assembly. Not a good choice if you need to frequently dismantle.
However for portable ops it is great, easy to get into the back of a car. I expect that over time it will prove to be a very durable antenna due to the excellent weatherproofing.
When assembling, I wrapped the phasing line in self-amalgamating and then poly tape, for extra protection from the elements.
It has replaced my cushcraft 124WB, which is also a very good antenna, a better choice if you need to dismantle, but I dont plan on doing that.
As the other reviewer said, add a light rotator and you will get superior results over an omni.
a great choice for portable emergency comms.
 
AB0RE Rating: 5/5 May 6, 2008 22:35 Send this review to a friend
M2 2M4 vs Arrow 146-4S  Time owned: 0 to 3 months
When I bought my first 4-element beam I was torn between the Arrow 146-4S and the M2 2M4. I purchased the Arrow 146-4S a few years ago (direct from Arrow) and the M2 2M4 a couple months ago (from AES). Having owned them both now I think it'd be fair to compare their similarities and differences. They both offer identical gain but have some differences in design that may make one more fitting for your particular situation than the other.


Boom / Elements:

The Arrow has a square aluminum boom which ensures you you have the antenna mounted exactly horizontal or vertical. The elements are 1/4" solid aluminum. The slip through the boom and are held in place with a screw that goes through the boom into a pre-tapped hole on each element - no measuring required! This design makes it easy to break down the antenna and re-assemble... great for portable work, camping, go-kits, etc.

The M2 has a round boom, so a little attention to detail is required to ensure the antenna ends up perfectly vertical or horizontal. The boom is a little lighter in construction. It has a secondary tube that slides inside the main boom to ensure the main boom is not crushed when the mast clamp is tightenened. The elements are 3/16" aluminum and are a bit easier to bend. (After putting my 2M4 together I discovered the rear element was bent. I called M2 and they immediately sent a complimentary replacement out via Priority Shipping. Kudos for great service there!!) The M2's elements are held in place with "keepers". Basically, the boom of the M2 has a hole drilled for each element. The elements are then passed through the boom through plastic insulating bushings on each side of the boom. The "keepers" (which resemble star washers) are then slid on each side of the element after the element is perfectly centered (by taking side-to-side measurements), thus "locking" the elements into place. M2 thoughtfully included a couple extra keepers because if they are pushed too far on the element they are nearly impossible to remove without damage. (This also does not make the 2M4 a good antenna to break-down and re-assemble.) Many reviewers make it sound like the keepers are a terrible burden, but don't let them scare you away. If you take your time assembling the 2M4 you'll be just fine.



Mast Clamps:

The Arrow has a mast saddle clamps cut from aluminum stock. They've got lots of "teeth" to ensure good mechanical attachment to your mounting mast. The Arrow antenna gives you the option of end-mounting the antenna or having it mounted mid-way along the boom. (If running vertical polarization with a metal mast you'd want to end mount to ensure no interaction between the mast and the vertical elements.) I have a couple complaints about the Arrow mast clamp. First, it has a lot of pieces. It's got the two mast clamps, two saddle clamps and four sets of nuts/bolts/lock washers. That's a lot of hardware to keep track of and it's quite cumbersome to get the Arrow antenna mounted to a mast up on a roof or the top of a tower. Second, the Arrow mast clamp is rated for masts 1.5" in diameter or less. It seems many of us run 2" masts if we have a tower or lots of antennas on the mast. For masts wider than 1.5", the mast clamps can be positioned "sideways" from what they are supposed to be for the desired polarization, one can bore out the mast clamp holes and replace the saddle clamps with a pair of muffler clamps that are positioned "long path" (from one mast clamp to the other). I believe I used a 7/16" drill bit to bore out the holes and a pair of 2.25" muffler clamps to facilitate mounting the Arrow 146-4s on a 1 7/8" mast.

The M2 has a glorified muffler clamp for its mast clamp. It only has two nuts and doesn't require a pair of wrenches to tighten it on the mast. It really works much better than the Arrow when installing it to a mast. The mast clamp of the M2 also has holes drilled out in case the user wants to replace the existing "muffler clamp" with a smaller one for a 1.5" mast. The representative I spoke to at M2 was adamant the antenna had to be mounted on *exactly* a 2" mast, or else it must be shimmed. I found it cinches up fine on my 1 7/8" mast. The 2M4 is a very lightweight antenna so I'm not at all worried about it falling off the mast the first time a strong wind comes along.



Tuning Network:

The Arrow antenna uses a gamma match. Per Arrows instructions, both the position of the metal tube and the position of the shorting bar affect both SWR and resonant frequency, but one affects SWR more and the other the resonant frequency more. I had great difficulty the first time I tuned a 146-4S. The final settings were nowhere near the recommended settings from Arrow. (The tube was pressed all the way in and touching the grommet.) I was able to get the entire band squeezed in under a 1.5:1 SWR, but it was a couple hours of tinkering that got me to that point. I'm not a huge fan of gamma matches as they are somewhat a mystery. I searched online and did not find fool-proof instructions for tuning. I basically tried *every* possible combination until I found one that worked. I wouldn't care to repeat that exercise. Coincidentally, the second 146-4S I put together appeared to be pretty much spot on with the suggested settings. Really, I'm at a loss for what may have gone wrong with the first tuning process. The connector on the 146-4S is a SO-239 but the antenna can also be purchased with an N connector.

The M2 using a tee-match (I think that's what they are called). They have a sealed balun that does the dirty work. The only adjustment is the position of the two shorting bars. I found the factory recommended settings were dead on and I was surprised to see I had the entire band well under 1.5:1 with no further adjustments. The balun was of amazing quality. The balun cable uses F-connectors and comes with gasketed nuts that are backed up tight against the F-connectors to ensure the assembly is weather proof. Honestly, I think a substantial portion of the 2M4's price can be attributed to the balun assembly. (M2 now offers "starter" antennas with gamma matches for substantially reduced prices.) If going with a tee-match instead of a gamma match saves as much headache as it did in my case, I'd almost say the tee-match is worth all the extra money spent. The 2M4 comes only with an N-connector. Two piece N-connectors can be had from AES, or one can go with the traditional N-connector if desired - assembly directions for the traditional N-connector can be found in April 2008's QST.



Overall Design / Value:

I'd have to say the Arrow 146-4S is built like a brick outhouse. That thing can take some serious abuse with no ill effects. It can easily be broken down and the elements stored inside the boom. It's almost criminal that one can get that antenna from Al at Arrow for a mere $59. If one is okay spending a little more time tuning and is okay with the 1.5" mast limitation (w/o modification), the Arrow is the perfect choice. The 146-4S would do well in very harsh environments or as an antenna that needs to be moved from location to location a lot. Al at Arrow is great at responding to questions via email.

The M2 2M4 would make a great starter antenna as well, especially considering the wide bandwidth and easy tuning. If the directions are followed carefully and one takes his time assembling the antenna, it appears to be nearly impossible to screw it up. At ~$129 it's not nearly a good of a deal as the Arrow but again, I'd suspect a lot of that cost has to do with the quality tee-match. M2's support is great and they have an extensive product line. (Sadly, Arrow does not produce anything larger than a 4-element VHF beam... Like me, I'm sure once you own one M2 antenna you'll appreciate the quality and attention to detail and want to upgrade to something even larger in the future.)

Both these antennas blow the pants off my Diamond X-50NA vertical antenna (rated at 4.5dBi of gain vs ~7.5dBD of gain on the beams). Please don't think you're making a terrible mistake going with a 4-element beam over a small to medium vertical antenna. With the beam properly positioned, signals seem to be several S-units stronger on the beam antennas. As an added plus, they can be turned with a cheap TV rotor (~$50 at Menards or other hardware stores) that can be controlled with cheap 3-wire control wire.

Thanks & 73,
Dan / ab0re
 


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