- Amateur Radio (Ham Radio) Community

Call Search

New to Ham Radio?
My Profile

Friends Remembered
Survey Question

DX Cluster Spots

Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement

Reviews Categories | Antennas: VHF/UHF+ Omnidirectional: verticals, mobile, etc | Diamond M285 Monoband (144-172Mhz) mobile antenna Help

Reviews Summary for Diamond M285 Monoband (144-172Mhz) mobile antenna
Diamond M285 Monoband (144-172Mhz) mobile antenna Reviews: 4 Average rating: 4.3/5 MSRP: $31.95
Description: Monoband antenna with PL-259 (UHF) connector. Length uncut is 52.4". Can be cut for any frequency between 144 and 172 Mhz. 3.4 dbi gain, 200 watts, 5/8 wave.
Product is in production.
More info:
Email Subscription
You are not subscribed to this review.

My Subscriptions
Subscriptions Help

You can write your own review of the Diamond M285 Monoband (144-172Mhz) mobile antenna.

WD8KDG Rating: 2/5 May 12, 2019 17:38 Send this review to a friend
Lost in translation  Time owned: more than 12 months
The M285S works, sort of. I now own two and used them a decade or more. Both did arrive with an instruction sheet and a cutting chart for the whip.

Lost in translation item #1: Grounding
The comments after are, Required for optimum performance. A phone call to the manufacturer cleared up the translation. "A ground plane is required for optimum performance. Don't bother grounding the mount!

Lost in translation item #2: Length
The comments after are, 50" (before cutting)
Same phone call cleared up this issue. The whip is not 50 inches in length. Most of us only cut the whip, I hope.

With two different vehicles, the whip needs to be 50" before cutting. As it arrives from the factory SWR is 2:1 on any transmitting frequency at 144.***. At 145MHz and above there is hope.
AI4HO Rating: 5/5 Jun 13, 2009 18:05 Send this review to a friend
First Impressions  Time owned: 0 to 3 months
This is strictly a first impressions type of review, having only had this antenna on my vehicle 2 weeks now. To kinda sorta set the stage here, let me first say that this is the first time using a not only a mono band antenna, but using an NMO style antenna and mount.

Before this, my antennas used to be the typical dual/tri/quad band antennas on typically a large 3 magnet mount. Well this last trip to Dayton saw me on the return trip with the Tar Heel 40A which is considerably larger than the Little Tar Heel II that I went up with. I figured I would have some interference issues, but when the locals say you are weak and scratchy into the repeater, then you know there are issues.

So enter the Diamond M285SNMO mono band antenna, and the Diamond K400C NMO mount. This antenna so far has done well on the local repeater, plus several of the other area repeaters. As previously stated it has only been 2 weeks and I haven't completed my testing. One thing that I had read, one of the other poster made mention of the fact that there had been no cut chart for tuning the antenna. In the packaging was a cut chart for tuning the antenna. Speaking of tuning, thought I was going to have to cut this antenna to get it tuned properly, not so, right out of the package onto the mount, and onto my SWR analyzer.

I check my SWR at its lowest, also at the low end then at the high end. From 144-148MHz the SWR is at 1.2:1, now then at 138.5 the SWR is 2.0:1 and at 153.8 the SWR is 2.0:1, all this means is I could conceivably Xmit on these frequencies, receive on the other hand, is all good, aircraft, public services, weather, etc. can all be heard. Now then, off to check out how well this antenna works on 2 meter SSB. A more thorough review in a few months.

73 de Mark
K4JC Rating: 5/5 Feb 22, 2007 19:11 Send this review to a friend
Works like a champ!  Time owned: 3 to 6 months
Excellent 2 meter 5/8-wave mobile antenna. I have mine trunk mounted with a Diamond K600 mount and this combination has proven extremely efficient.

The M285S (really, any 5/8-wave 2 meter antenna) has the added advantage of being a 1/4-wave 6 meter antenna. (You can also buy the M685S sold as a 6 meter 1/4-wave, but it's really the same antenna! Go figure...) SWR after proper tuning is 1.1:1 at 146 MHz, and 1.2:1 at 52.5 MHz. Also very good for reception of public service and 162 MHz WX bands. Construction is pretty solid. Comes in a UHF or NMO mount version.

If you're looking for a good antenna with a bit of gain, this one will fill the bill.
N2LJ Rating: 5/5 Mar 1, 2006 10:06 Send this review to a friend
Good antenna, does the trick.  Time owned: more than 12 months
If you have any need for a monoband antenna for a frequency outside of the Amateur 2 meter band, you could do worse than this Diamond. It comes uncut, and you cut it to the length needed.

My application was for the Marine VHF-FM Band, as I am a Land Mobile Radio Operator with the US Coast Guard Auxiliary. I cut the antenna for about 157.125 Mhz. Works well in conjunction with a Diamond K412C mount on the rear door.

Only one issue was that the antenna didn't come with the cut chart, and when I called Diamond, the tech initially told me it was cut for the frequency it is supposed to be used for! I had to explain to him what his product was, and finally, a cut chart came in the mail. They now have the chart on the web page. I verified my cut with an MFJ 259B, and all is well.

Even cut for 157 Mhz, it was a darn sight better than my Diamond NR770HB when it's coil went the way many of them seem to do!

Good antenna, if you can use it!

If you have any questions, problems, or suggestions about Reviews, please email your Reviews Manager.