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Reviews Categories | Antennas: VHF/UHF+ Omnidirectional: verticals, mobile, etc | Larsen NMO 2/70 Help


Reviews Summary for Larsen NMO 2/70
Larsen NMO 2/70 Reviews: 42 Average rating: 4.7/5 MSRP: $54.00 @ HRO
Description: dual-band 2m/440 nmo mount mobile
Product is in production.
More info: http://www.radialllarsen.com
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AJ6B Rating: 5/5 May 12, 2010 00:34 Send this review to a friend
Exceller Performer  Time owned: 3 to 6 months
No reviews in awhile, thought I would drop one in here..

Purchased my Larsen NMO2/70B about 6 months ago and it has been flawless. I like how the Larsen antennas seal on to my vehicle. I have since replaced my Comets all with Larsen just from the way they seal.

I am using the NMO2/70B as there is also the NMO2/70C. From what it looks like, the "B" version has the coil in the base and the "C" version has the coil in the middle of the whip. I chose to get the base loaded version as if anything happends to the whip, you can order replacement parts from Larsen.
 
KI4RGD Rating: 5/5 Jul 13, 2009 18:14 Send this review to a friend
Didn't work on my Jeep.  Time owned: 0 to 3 months
I have a 2-door Jeep Wrangler, soft-top. My VHF/UHF and HF antennas are mounted on a specialized antenna mount coming off the gate either side of the spare tire. I'm currently running a Diamond 770NMO with great results.

After reading the reviews for this antenna, I thought I would invest in one and try it out. SWR stayed at 3.1 to 3.5 on all VHF freq. My Diamond 770NMO's SWR stays under 2.0 and 1.5 - not bad. I took the Larsen off and plan to send it back, if HRO will let me.

Dont get the wrong idea about this antenna, I'm sure its a hum-dinger like everyone else has reviewed. I'll keep my review # at a 5 becuase I'm sure it would work on a different vehicle. Jeeps are notorious for being difficult in mounting and operating antennas. There isn't much ground to work with. And yes - the tailgate is grounded, along with multiple points underneath, etc.. Since my Diamond 770 is working - I'll stick with it. Whats the saying, "if it ain't broke - don't swap it out."
 
KC5MO Rating: 5/5 Jul 5, 2009 10:30 Send this review to a friend
Tough and reliable  Time owned: more than 12 months
I have had my Larsen NMO 2/70 for 15 years now and have had no problems at all. Tunes up great ( the NMO mound MUST make contact with the under side of the roof ) and it take abuse! I wouldn't expect less from Larsen.
 
N0XMZ Rating: 5/5 Jun 26, 2009 13:00 Send this review to a friend
I wouldn't buy any other  Time owned: more than 12 months
I've been using the open-coil version for almost 3 years and I'm very satisfied with the performance. The only thing I'd change is the set screw as it does corrode over time.
 
KD4ONT Rating: 5/5 Apr 17, 2009 11:24 Send this review to a friend
Great antenna that's built to last.  Time owned: more than 12 months
The first 2/70 I bought must be at least 16 years old and still works like a charm! Granted, it's been on 3+ cars during that time, and pretty beaten up by hitting things with it and being buried in the bottom of the trunk for years. I liked it so much I bought a second one (that had been collecting dust on the shelf at my local ham radio shop for a long time) just because it would be nice to have a new back-up one, just in case the old one gave up the ghost someday. On the car it's on now, it's installed on a trunk lip mount on the middle-side of the deck (because my trunk is short, in back of the window the trunk lip slightly curves up so it's not flat there, and the trunk opens past a 90 degree angle so any antenna would hit the window/roof before it's fully open). I know this isn't the best spot to mount it, but considering I go into parking garages almost daily, it'll do for now. The SWR's are practically flat on UHF but VHF, they're not wanting to com down flat when tuning the antenna. They seem to be between 1.5 to 1.7 in the amateur band there. I know, it's not "perfect" but it's in an acceptable range all things considered and with the compromises typical with multiband antennas. I do remember when tuning it last time, it appeared as if the VHF side might benefit from the whip being a little bit longer, but I suspect that would throw the balance between the middle and base coils off too much.

I've compared this antenna to a few others and always seem to come back to the Larsen because of it's quality build, lack of rusting, open air coil, hasn't burnt up with stock radio power, and it performs well for it's size.

I've read literature online about them and it only states that the 2/70 is 1/2 wave center loaded at VHF and collinear on UHF. During my antenna testing recently (with mainly D-Star), I started wondering why some wavelength antennas work better in different areas and surroundings than others (residential, downtown, areas of somewhat dense "RF eating" tree population, highways, fringe repeater areas and simplex). I happened to stumble upon this website which explained things in an easy to understand way for different wavelength antennas: http://www.hamradioindia.org/circuits/radiation_pattern.php

I also shot off an email to Larsen, asking them for more information on this antenna, mainly on what wavelength(s) is the mysterious collinear UHF side of this antenna? Here is my email and the response:

To: Larsen Info
Subject: Technical question about amateur NMO 2/70 antenna



I've been testing your antenna, along with others, with D-Star amateur digital repeaters. The information given on the NMO 2/70 is that it's a dual band, 1/2 wave center loaded on VHF and collinear on UHF. My question is, what wavelengths does the UHF side use? 5/8 over 1/4, 1/2, 5/8 or something else? From what I'm beginning to learn about take-off angles of radiation with antennas, makes me wonder what it could be? If someone could shed some light on this, I'd be very grateful for their help.

Thank you

Here's their response:

Greetings,

Great questions!

The 2/70 is listed as a a UHF collinear and a center loaded VHF.

The loading for VHF comes from the coil placed in the center of the whip. This coil, however, is also designed to phase the top and bottom sections for UHF. Both the top and bottom sections of the whip are 5/8 wavelengths (roughly) at 445 MHz. The base coil helps impedance match both VHF and UHF. This antenna design is very tricky - and picky in terms of mounting because of the narrow tuning characteristics.

It is interesting that you are looking at take-off angles. As you are probably aware - if delving this deep into antenna theory - the ground plane characteristics (such as the vehicle size / shape) combined with the height above earth ground all play into the radiation performance specific to take-off angles and radiation theory. It gets very complicated to look at!



Best regards,

Aaron, KD7PCD

I hope this information and my experience helps out someone now or in the future with this or any other antenna. And like the article above states: "The vertical antennas has its own behaviors in gain, radiation angle, effective aperture etc. But you have to choose for the best antennas for your own purpose. "Whether we buy or build our antennas, we soon find out that is no one 'best' design for all purposes" - ARRL - 1978, Page 623 - Hi."

In closing, my experience with the Larsen NMO 2/70 black, open air coil design, is that this is a worthy and well built antenna for the mobile that's not an eyesore an will last a very long time. I would recommend it to the average person under average usage circumstances; someone who doesn't want to run dual mono band (VHF/UHF) antennas or overseas built antennas. It's not that big and not ugly either ;)
 
N0UJQ Rating: 5/5 Mar 30, 2009 20:34 Send this review to a friend
The Standard all others are compared to  Time owned: more than 12 months
(This review applies to both the open-coil, and the closed coil versions)

First off, evidently the previous reviewer had a bad coil from the factory. A quick phone call would have resolved that issue.

That aside,
I've owned and otherwise used about 15 Larsen NMO 2/70 antennas in the past 20 years. Some of them on farm tractors. I can tell you they last between 10 and 15 years under that kind of use - i've had two coils go bad during that time period. They take a reasonable amount of tree-bashing and hail damage before the UHF portion just gives up.

The 2 meter performance is very good, essentially as good as the best 5/8 wave mobile antennas, except with a shorter whip that doesn't flex in the wind so much.

The 70cm portion is fabulous, better than i've seen on any other mobile antenna, really. And i've used those super-size Comet/Diamond antennas only to find out they don't perform as well as a Larson, and they sure as heck don't last as long. Part of the reason being that the higher gain antennas are shooting sky-wave while you're going 65MPH down interstate.

Are you an FT-8900 owner looking for an antenna? Forget the UHV-4 and forget the CR-8900. Just get a Larson NMO 2/70, NMO27C, and NMO50C. Switch them out as needed or get a duplexer (Comet CF-360B) that will allow you to run the 2/70 the same time as the low band antenna of your choice. Your 2 meter/70cm performance shouldn't suffer just because you *might* someday work 6 or 10 meters with your mobile rig!

Without a doubt, 5 stars
 
N1IER Rating: 1/5 Nov 14, 2008 20:17 Send this review to a friend
Disappointed  Time owned: 0 to 3 months
I donít know what happened but I just bought one of these antennas to replace a Larsen 2/70 mag-mount and it just plain doesnít work. I am using a NMO mount in the center of the roof of my truck and yes I scraped the paint off to get a good ground. Right out of the package the match on 2 meters was over 3:1. I read the instructions again telling me that it was factory tuned but my swr bridge told a different story. So out came the cutters, I tuned it on 2 meters and got the swr down to 1.2:1 center band and 1.7:1 high and low. Now I check 440 and itís over 3:1 on 440 and just under 2:1 at 450. I replaced it with a Diamond NR72BNMO that Iíve had for 6+ years and the match was below1.3:1 across both bands. What happened to Larsen quality???
 
K7BAB Rating: 4/5 Sep 29, 2008 20:24 Send this review to a friend
Good Factory Support  Time owned: 6 to 12 months
Well build and rugged. The best part is the support from Larsen.
 
NE4ME Rating: 5/5 Dec 23, 2007 09:23 Send this review to a friend
Best overall performer!  Time owned: more than 12 months
Antenna does great on VHF and awesome on UHF. I have ran several other brand antennas on 2m and 440 and none can compete with this one for both 2m and 440. Only ran across two that can compete with this one on 2m and that is the Larsen NMO150 and then the Hustler 5/8 over 1/4 wave CGT-144 and both are much larger than this Larsen dualbander. I have to admit I am brand loyal when it comes to Larsen and I will no longer run anything else when it comes to VHF/UHF mobile, unless the other companies really come out with something that can compete with what Larsen sells. I have Larsen mobile antennas for 10m, 6m, 2m, 220, and 440 and they all seem to perform well, but I have not been able to do any comparisons on 6m and 10m though. I can only say one thing negative about any Larsen product and that is the little 17" 2m/440 dual bander. That little one is fair at best on 2m and is terrible on 440! I'd rather have a 1/4 wave on 2m than that little dual bander, but I'd rather have most rubber ducks than that little dual bander on 440. Other than that mini dual bander, I think that all the other Larsen products that I have used through the years (and continue to use) are excellent performers and stand up to pleny of abuse. I have been exclusively been running Larsen mobile antennas for the last 12 years after about 3 years of experimenting with all the other "big name" wanna-be antennas out there. Go Larsen and you won't go wrong. Excellent bandwidth, real gain, real rugged....Rusty NE4ME
 
KN4X Rating: 5/5 May 18, 2007 13:23 Send this review to a friend
Solid and steady, good value.  Time owned: more than 12 months
Current version NMO 2/70B, black coil - open coil black whip. To begin with, this antenna is not a "high performance" Asian antenna.

Pros:
rugged, dependable, and steady performer that will deliver above average performance over the long haul. Very simple and clean design. Rigid enough at highway speeds (about 25-30 degree bend max). Will take an impact without distorting if impact is in top 1/3. An add-on Larsen spring is available for US$10 if hitting objects is a regular concern. Maintenance free if properly installed. Will outlast Diamond and Comet antennas by 10+ years with reasonable care.

Cons:
Not one of the higher gain 2m/70cm antennas available today. Whip can be bent if impacted in bottom half (however unlike a Diamond, Comet, etc. it can easily be reshaped).

Experience with my nmo antennas and others has exposed the nmo mounts biggest weakness, improper installation. Be sure to remove the paint on both the UNDERSIDE and top side of the hole if mounted in a thru-the-hole mount. A good ground is critical to obtain and maintain a 1:1 center of band swr. Mount it right the first time and enjoy. It'll probably outlive you.
 
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