Batboard

Has anyone ever used the Diamond NR72BNMO? Description says it's is a 2 meter and 440 MHz (70 cm) mobile antenna. It is a 1/4 wave on 2 meters providing 2.15 dBi gain and a 1/2 wave on 440 providing 2.15 dB gain. This antenna can handle up to 100 watts. VSWR is less than 1.5:1. A hexagonal (Allen) wrench is included for adjustment.

This antenna is approximately 13.8 inches (.38 m) high. The antenna is black, very well built and looks a bit like a cellular antenna. The connector type is NMO.

I'd be using it mostly for scanning in the 150 and 450-512 range on a trunk lip mount, occassional 2m and 440 ham use. Any reviews/comments ?

The dBi gain figures are exaggerated. The antenna is a 1/4w on VHF, therefore it has no real gain, but with a groundplane the UHF gain in dBd should be close to the advertised dBi figure.

I see alot of hammies around here with them, so they must not be too bad...?

It's a unity gain antenna. dBi is gain in dB over isotropic - a perfect radiator, which doesn't exist. A more telling measurement is dBd - dB over a dipole. The conversion factor? 0dBd = 2.15dBi.

It's still physically too short for a full 1/4 wave on VHF. How much radiated signal is getting converted to heat in whatever coil thingy is at the bottom of the antenna?

As an alternative, take a look at the Comet SBB-2NMO. 18" long, 2.15dBi on 146MHz, 3.8dBi on 446MHz. I used to think that Comet antennas were cheap knock-offs of Diamonds, but Comet's quality seems to have gotten better over the years.

Bob...

I use an SSB-2NMO mounted on the roof of my car and it works well. Sure it won't outperform a 5/8 whip but when you've got height restrictions it's a great solution.

After much personal reflection, I recall that I owned a Comet SBB-2NMO for a while. It was mounted on the luggage rack on my Ford Explorer using a Diamond mount of some sort. I forgot the antenna was there one day and put the Exploder in the garage. Snapped that Comet right off. The ferrule where the whip attaches broke away from the body of the antenna base.

Stiff whips are a good thing for reducing "mobile flutter", but you gotta keep in mind that they will more likely break something rather than bend.

Bob...

About six years ago I bought a short NMO dualbander from
Antenna World in Miami. It shows very little reflected power
on 146 and 446 mHz and seems to work well all over my
home area. Sometimes when I travel to the "country" and
I remember to do so I change to a longer dualbander but in
all honesty the short antenna works very well. And it's a
rare occasion when the antenna hits a sprinkler pipe in a
garage; usually it clears the pipes.

got one works great low swr when permanatly mounted

It works great, seems to handle 100 watts. However, it is VERY narrowbanded. Don't expect to operate outside the ham one with this one, on either vhf or uhf.

k4iii wrote:It works great, seems to handle 100 watts. However, it is VERY narrowbanded. Don't expect to operate outside the ham one with this one, on either vhf or uhf.

And you Lazarused a 15-month-old post why?