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eHam Forums => Mobile Ham => Topic started by: KC0FTC on January 05, 2010, 11:03:30 PM



Title: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 05, 2010, 11:03:30 PM
I'm looking at getting a Diamond NR22L antenna to put on top of my Jeep Cherokee.  It does have a luggage rack.   I'd like to be able to fold it down easliy.  There are several mounts out there but haven't came across one for a 96 inch antenna.  I'd also like to run LMR-400 to the radio so I need a mount that I have to use my own cable with.  

For those Cherokee owners, what did you use and how did you mount it?

thanks


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 06, 2010, 12:48:11 AM
Diamond does have the K400-C but I don't want to use that thin RG316.


Title: RE: Antenna mount for Jeep Cherokee
Post by: K0BG on January 06, 2010, 06:27:51 AM
The Diamond antenna in question does have a fold over built in.

I'm not fond of any of the Pacific Rim antennas, as their ruggedness is in question. What's more, they publish calculated gain figures in dBi, and sometimes leave of the 'i' as if to mislead buyers. But if you really dig into the designs, you'll see the coils are rather low Q, so what little gain they do have is mediated by the losses. These reasons are why two way shops don't use them.

The truth is, you'd probably be better off with a 1/4 wave NMO mounted directly. If most of your transmissions are through repeaters, you'll never notice.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 04:33:17 AM
You mentioned Pacific Rim Antennas. Is that another name for Diamond Antennas?  I used to have a Diamond SG2000HD. Wow, that antenna could get into repeaters a long ways away.  I once got into a repeater 120 miles away using one.  60+ miles for most other repeaters with a 45 watt Radio Shack HTX 242.  Loved that antenna. Got into a Winsconsin repeater from Missouri via troposheric ducting.  I had it on a magnet mount and used fishing line to secure it from falling over, worked great.  That was on my old Neon.  

I was thinking of the NR22L antenna with the K400C mount.  But I really don't want to use RG316.  Is there another mount that I can use with the NR22L that doesn't use RG316?  I'd like to use LMR 400.  

Thanks


Title: RE: Antenna mount for Jeep Cherokee
Post by: K0BG on January 07, 2010, 06:07:30 AM
Pacific Rim refers to off shore manufacturers like those in China, Japan, Malaysia, Korea, and of course the Philippines. Some of the products produced are wonderful, and in fact the vast majority of US purchases (electronics, cars, etc.) come from the Pacific Rim. Unfortunately, some of it is junk. Here's my take.

I haven't seen any antennas from Diamond or Comet, that I would own. The reasons are varied, but the most significant one is their basic structure. Any time you connect antenna parts together with set screws, the ruggedness goes out the window. The phasing coils are often wound with small wire which makes them lossy (low Q). Adding some insult, they're encapsulated which further reduces Q. Their (calculated) gain figures are always advertised in dBi, if indeed the 'i' is present, to make them appear better than their US counterparts which typically show gain is dBd. They do this because they know people play the gain game, as if that is the only thing which counts. It isn't.

Proper mounting is key to antenna performance. Mag mounts, clip mounts, and such, add ground loss. Making matters a bit worse, the mount style used by too many Pacific Rim antennas, are modifications of an SO239. They were never meant to be antenna mounts. Most of them leak, even with the antenna attached. A properly installed NMO won't leak period, even with the antenna removed. And speaking of which, both Diamonds and Comets NMO style mount in incompatible with a (New Motorola) NMO.

And, the coax they use on their K400 type mounts is rather lossy, prompting some to choose a different coax as you have. The truth is, a good grade of RG8X is probably the best choice all around. Unfortunately, you can't bend it around corners like the cheap stuff, but if you install your antennas like you should (drilling a hole), the bending issue is moot.

There is a lot more involved in operating safely while mobile-in-motion, than tossing a radio in the front seat, and sticking on a mag mount; dis aliter visum.

Alan, KØBG
www.k0bg.com


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 01:29:28 PM
What would you suggest for an anenna and mount or my cherokee?  Thanks


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 01:50:38 PM
I know drilling would be the best option but there is no way that I'm going to drill a hole in my Jeep.  This is the first time I've heard negative things about Diamond Antennas, I sure loved my SG200HD, that antenna sure got out.  They were the antenna to get back 11 years ago when I got into this.  
Anyways, I'm always up for suggestions.  I want the highest gain antenna with a good mount and low loss cable without having to drill a hole.  It also need to be able to be folded over so I can pull into my garage.

Thanks


Title: RE: Antenna mount for Jeep Cherokee
Post by: K0BG on January 07, 2010, 03:17:28 PM
Ask yourself this question: Why don't I see Diamond and Comet antenna sold by two way radio shops?

If I can find it, I'll e-mail you (you do have your e-mail posted?) a pix of a Tokyo police Toyota Supra. On the roof is a Larsen NMO150, and NMO450, and what appeared to be a Larsen GPS antenna. Sort of speaks volumes.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 04:10:00 PM
My e-mail is Aaron1100us@yahoo.com.  I had a Motorola VHF 2 way in my Neon once.  I had a Larsen Mag mount and antenna.  Wasn't really impressed with the quality of that particular mount and antenna, seemed cheap.  The connections inside the mag mount corroded from moisture entering.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 04:11:53 PM
Is there a good quality Larsen mount and antenna that would be good?


Title: RE: Antenna mount for Jeep Cherokee
Post by: K0BG on January 07, 2010, 05:58:24 PM
I thought I gave it to you: NMO2/70BK.

Just for the record...

I don't like mag mounts, no matter who made them. You always run a good risk of having alternator whine, especially on transmit. They do come off, and just because that never happened to you previously, doesn't mean much. Four years ago, an Ohio woman was killed when a mag mount dislodged from a plain clothes police car. I wonder what she thought at the time? To me, it just isn't worth the effort.

Alan, KØBG
www.k0bg.com


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 06:20:31 PM
Thanks.  That antenna looks good and a good price too.  Good reviews on here.  Ok, what mount should I use that would let me use LMR 240 or othe low loss coax?  No holes and no mag mount.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 10:37:53 PM
I'm thinking about the NMO-150 single band antenna.  I was looking at mounts and did not see any adjustable lip mounts, only mag mounts and a non adjustable trunk lip mount.  I would like a mount that I can fold the antenna over so I can put the Jeep in the garage.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 07, 2010, 10:46:44 PM
What about the Comet RS-720/RS-720NMO
Med-duty, 3 adjustment planes, up to 60” antenna. The RS-720NMO has a 3/4” hole to accept an NMO mount. And the Larsen NMOK NMO [Motorola] Roof Mount with 17 feet of RG-58A/U?


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 08, 2010, 04:09:22 PM
Ended up ordering a Larsen NMO 150 antenna and Larsen NMO mag mount with RG-58.  The mag mount is only temporary untill I can find the correct mount that I want that I an use LMR-420 with.  I also ordered an MFJ 842 SWR meter and a 3 foot section of LMR-240 to got between the SWR and radio.


Title: RE: Antenna mount for Jeep Cherokee
Post by: K0BG on January 09, 2010, 07:22:35 AM
You won't need the SWR bridge. If you set the antenna like the instructions say, the SWR will be spot on.

You don't need the SWR bridge afterwards,, as it won't tell you anything you can't get from the radio itself. One things for sure, it's just another piece of hardware to find room for.

I run an amp in HF, and I don't use one. If the SWR gets too high, the amp just kicks off, and the on light goes out. I just push the Tune button, and presto, the controller does the tuning. I don't even have to take my eyes off the road.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC0FTC on January 10, 2010, 07:05:33 AM
Suppose I probably shouldn't have ordered the SWR meter but oh well.  I'll check the SWR with it but won't leave it hooked up.

I'm excited to see the performance of this Larsen antenna.


Title: RE: Antenna mount for Jeep Cherokee
Post by: KC9CFM on January 15, 2010, 01:39:00 PM
I know what you said, but really - Drill a hole in your roof.  I drilled a hole in my Jeep Cherokee several years ago and installed a NMO mount.  Works great and I tell you, the first time is the hardest - then it gets easier.  It was much easier when I drilled my second hole, into a Hyundai Accent.  Another NMO mount, works great!

I got a "rain cap" for it - when I sell it someday, I will just plop the rain cap on and be done with it.

Jamie