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Author Topic: New Ham with Mobile Q's  (Read 2290 times)
KC9TJK
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« on: December 01, 2010, 02:18:36 PM »

Just to start off, I am completely new to Amateur Radio (just got my call sign yesterday). I currently own a Yaesu VX6R HT that I plan to use as a very temporary mobile setup. I know this isn't the most useful application for an HT, however, it will only be used in this fashion until I have the green to purchase a good mobile.

My questions are in regards to mobile antenna type and configuration. What antenna setup would give me the best performance?I have noticed on the sites that I have looked at that most people use two separate antennas for 2m and 70 cm. Are these antennas ran through a duplexer and then connected to the radio? Is there any advantage to that setup as opposed to just using a single dualband antenna? I am not concerned about HF right now either.

I realize I have a lot to learn and look forward to doing so. Any and all responses are appreciated.

KC9TJK
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W3LK
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« Reply #1 on: December 01, 2010, 02:24:01 PM »

There is no particular advantage (in amateur radio) of using separate VHF and UHF antennas.

As for a particular antenna, the best antenna on the market is the Larsen NMO270B mounted in the middle of the roof or trunk deck with an american-made NMO through-hole mount.

Be advised, that using an external antenna like this may well overload the front-end of your HT. For city work, it is quite possible an external antenna is not necessary to hit the local repeaters. Try it first before pursuing the external antenna route.

Welcome Abord!
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KC9TJK
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« Reply #2 on: December 01, 2010, 02:38:35 PM »

Thanks for the reply and the welcome. I did come across that particular antenna in my searching. My bigger concern with the NMO mounts is that I have a 2010 Tundra and am a bit concerned about drilling holes in the roof. I know it's a give and take no matter what you look at. I do like the "clean" look of the NMOs though.

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W3LK
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« Reply #3 on: December 01, 2010, 02:52:22 PM »

Thanks for the reply and the welcome. I did come across that particular antenna in my searching. My bigger concern with the NMO mounts is that I have a 2010 Tundra and am a bit concerned about drilling holes in the roof. I know it's a give and take no matter what you look at. I do like the "clean" look of the NMOs though.

There is no problem installing an NMO mount as long as you do your homework as to the location of cross members. Properly installed, a US-made NMO mount is water-proof, even without an antenna installed on it. This does NOT hold true for foreign-made mounts. In 30+ years of installing antennas, I have yet to have one ever leak, even running through car washes without the antennas on the mounts.

Also, the urban myth about holes destroying resale value is just that, an urban myth. When you sell the vehicle, you can either remove the mount and close the hole with a Motorola rubber plug or put a 1/4 wave UHF antenna on it. I've done it both ways over the years and have yet to have a dealer pay any attention either way. My experience come from both personal vehicle and company vehicles. I was the fleet manager for my company for several years.
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KC9TJK
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« Reply #4 on: December 01, 2010, 03:08:00 PM »

Tapping your expertise then... Where is the best place to get "US made" NMO mounts? I have briefly looked at a couple of sites but they don't indicate origin of manufacture.

Also, I didn't realize they were that cheap (as opposed to special mounting brackets, etc). I checked out a Tundra site where an owner installed three of these and put caps on them. Looks very professional and clean.
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K5LXP
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« Reply #5 on: December 01, 2010, 03:10:37 PM »

I think two single/one dual antenna option depends on a number of factors.

A single dual band antenna is pretty convenient, and there's only one mount to install.  But depending on the mobile rig you get, if you have to buy a diplexer to connect to separate V and U ports on the radio it might be a tad cheaper to just use two quarter wave whips.  Likewise with a single port radio, if you have separate antennas you need the diplexer to connect them up so a single antenna makes a bit more sense.

Then there's available real estate on the roof, and how many other radios you may want to install.  If you decide you wanted to run 6M or 10M FM, you'd probably be better off with separate antennas for those because it gives you more choices for antennas offering better performance.  If you want to have APRS you're probably going to want a dedicated antenna for that.  So think about future expansion when considering mount placement and cable routing.  You could just put 3 or 4 mounts in right away and you'd be ready for most any configuration now and in the future.  By using NMO mounts you can put many different brands of antennas covering HF through GHz and swap around at will.

Visit K0BG.com and spend some time reading up on everything you need to know.


Mark K5LXP
Albuquerque, NM
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K0BG
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« Reply #6 on: December 01, 2010, 03:17:58 PM »

AES, HRO, R&L, and many others are Larsen dealers. The nomenclature Lon gave you (NMO2/70BK) is correct, however, most dealers list it as two separate parts. The NMO2/70B which is the all black coil, Kulrod (copper) plated black whip, and the actual NMO mount is a NMOKLCP complete with PL259.
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KC9TJK
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« Reply #7 on: December 01, 2010, 05:05:50 PM »

Thanks to everyone for their responses so far. I discovered this link (below) for a guy who installed 3 NMO mounts on his Tundra. Again, it looks very clean. The only question is, who manufactures "American" NMO mounts? I haven't seen any with manufacturer specified.

http://www.tundratalk.net/forums/tundra-audio-visual-discussion/76482-nmo-antenna-mount-installation-new-tundra-crewmax.html
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KC9TJK
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« Reply #8 on: December 01, 2010, 05:08:07 PM »

Disregard... Found it in another thread...

Motorola, Larsen or AnteneX
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KE4DRN
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« Reply #9 on: December 01, 2010, 06:15:55 PM »

hi

http://kollmanradio.com/

73 james
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K2YO
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« Reply #10 on: December 01, 2010, 10:11:59 PM »

Craig,
If you are nervous about drilling or the headliner, talk to a local custom stereo shop. They tend to like custom jobs like this because it new and different than they typical. They will know the ins and outs of the headliner and trim panels.

If you decide to do it yourself, make sure to wash your hands before touching the headliners. Once you think they are clean, wash then again, hahahahha. Headliners are easy to get dirty and impossible to clean!

For the drilling, don't worry, that nervious feeling of putting cutting tools to paint goes away quickly. I drilled my BMW and once the mount was in the hole, all the bad feelings went away.

Bernie
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KQ6Q
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« Reply #11 on: December 20, 2010, 11:23:12 AM »

If you haven't already made the hole in the roof, consider whether you will EVER have to drive into a parking garage with a clearance of 7 feet, or perhaps even 6 1/2 feet. The ideal antenna on the roof isn't nearly as ideal when it goes whap whap whap on the overhead beams in the garage, and then gets bent over flat or breaks off.
The garage at my work has 6/6" clearance, and I get by with a short 2m/440 whip mounted on the front fender of my Honda Element, with bracket coming out of the edge of the hood opening.
If you live in country where you have 10-14' clearance everywhere you go, enjoy the top center antenna location!
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W3LK
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« Reply #12 on: December 20, 2010, 03:51:00 PM »

If you haven't already made the hole in the roof, consider whether you will EVER have to drive into a parking garage with a clearance of 7 feet, or perhaps even 6 1/2 feet. The ideal antenna on the roof isn't nearly as ideal when it goes whap whap whap on the overhead beams in the garage, and then gets bent over flat or breaks off.
The garage at my work has 6/6" clearance, and I get by with a short 2m/440 whip mounted on the front fender of my Honda Element, with bracket coming out of the edge of the hood opening.
If you live in country where you have 10-14' clearance everywhere you go, enjoy the top center antenna location!

All depends upon the antenna and installation.

I have a 12-year old Larsen NMO270 that is on its third Ford Windstar and is mounted in the center of the roof over the forward dome light. I have a Larsen 6m centered over the rear dome light. For about 6 years I was in and out of the parking garage twice a week at BWI in Baltimore with 7' clearances; I never removed the antennas; I just drove slowly. I will tell you that the jointed Diamond and Comet antennas will be destroyed by such antics, but the Larsen survive nicely.

On the rare occasion that I have to enter someplace with less clearance, it tale all of 30 seconds per antenna to unscrew them from the NMO mount.

FWIW, I have been installing Larsens on vehicles, short and tall, for several years and have yet to have one break off or be bent out of shape. Most of these installations were in agency disaster-related vehicles.
« Last Edit: December 20, 2010, 03:56:13 PM by Lon Kinley » Logged

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K0BG
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« Reply #13 on: December 20, 2010, 06:18:20 PM »

I have a Larsen NMO2/70BK. It is about 15 years old. It has had about 5 different NMO mounts under it. It has been crushed in the garage door twice. All I have ever done was to straighten out the whip. If it had been a Comet or Diamond, I would have had about 6 or 8 different ones. Go figure!
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KJ1H
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« Reply #14 on: December 25, 2010, 04:47:11 PM »

In a few different vehicles I've simply removed the interior dome light and drilled my hole through the roof right above it.  That gives me easy access to install the mount without having to drop the headliner.  It also helps me center the antenna on the roof, since the dome light is centered.
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73 - Justin
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