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Author Topic: Best mount style?  (Read 4441 times)
NV1P
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Posts: 73




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« on: January 05, 2012, 10:22:35 AM »

I'm thinking of buying a trunk lip mount for a few antennas I already have, as well as some I plan to get. I've been looking around, and I think I'm going to go with the K400 from diamond, though I welcome any suggestions. The question is, which should I get? Is NMO better than UHF or 3/8-24? I'm planning to use the mount for 2m as well as 10 and maybe 15. I also noticed that they sell a k400 without mount (just the bracket). Do they sell interchangeable mounts? I haven't seen them.

Thanks and 73s,

NV1P
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NV1P
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« Reply #1 on: January 06, 2012, 10:00:11 AM »

I have decided to go with an NMO mount and then use adapters to other style antenna mounts. Is this a good idea? Are there adapters out there strong enough for this plan to work?
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NV1P
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« Reply #2 on: January 06, 2012, 10:20:20 AM »

I'm planning to use the mount for 2m as well as 10 and maybe 15.

It's going to be used on a Honda Fit Sport.
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WB6BYU
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« Reply #3 on: January 06, 2012, 01:08:57 PM »

The NMO is the best option for VHF/UHF.  I'd avoid the PL-259 style unless it is important
to be able to connect a length of coax to the mount.

The NMO allows for the antenna to have a ground connection - this is important for some
matching networks.  The 3/8-24 stud just connects to the center conductor of the coax,
without the shield.  That's not a bad approach for whips that are 1/4 wave or shorter
(though it makes it more difficult to use a shunt coil for matching) which is why it is used
for many HF antennas.  A common approach would be to have two mounts, an NMO for
VHF/UHF and a 3/8-24 for HF.  If you are limited to one, you have to decide which is
more important for you.  You can get NMO antennas down to at least 10m, and might
be able to convert one to 15m by inserting a longer whip.  The 3/8-24 mount limits your
options for VHF/UHF - it will work with a quarter wave vertical (at least through 2m)
but there aren't a lot of other antennas available.
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NV1P
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Posts: 73




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« Reply #4 on: January 07, 2012, 02:06:08 PM »

The NMO is the best option for VHF/UHF.  ....  The 3/8-24 mount limits your
options for VHF/UHF...

First off, thank you for your reply and advice. I'm going to go with the NMO, but it's funny that the two 2 meter antennas I'm looking at (Diamond NR22L and Hustler CG-144) are PL-259/SO-239 and 3/8" x 24. I'll probably just use adapters for the NMO to either one.

73s

NV1P
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K1CJS
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« Reply #5 on: January 11, 2012, 06:16:33 AM »

NMO is the best--for shorter antennas.  As the antenna gets longer and more top heavy, a 3/8-24 thread type mount is better.  That is why that type is the type you'll find on Hamstiks and other such antennas.
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NV1P
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« Reply #6 on: January 11, 2012, 10:15:39 AM »

Well, I just ordered an NMO mount and an adapter. Do you think that it won't be structurally sound enough to support the large antenna (Hustler CG-144) I'm putting on the mount?
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K1CJS
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« Reply #7 on: January 14, 2012, 04:10:25 AM »

With just under 2 pounds worth of antenna in a 7 foot length, I think you would be overstraining the mount.  NMO mounts were meant to support light, short antennas, not the monster that the CG-144 is.  There's a reason that that antenna is supplied with the 3/8-24 mounting connector.

The only way that I would use an antenna that long on an NMO mount is if I was going to use it while the vehicle it was on was parked.  Even then, the force of the wind on the antenna could well overstress the NMO mount.  I would definitely NOT use such a setup on a moving vehicle.

Added--  If you want to use that antenna on a moving vehicle, you need to get the antenna package that Hustler sells with the trunk lip mount--as a bare minimum.  If I were you, I would get a good, solid ball type 3/8-24 mount.  It doesn't look all that good, but it is the only style mount that will support that antenna with no problems.
« Last Edit: January 14, 2012, 04:17:17 AM by K1CJS » Logged
KI4SDY
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Posts: 1458




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« Reply #8 on: January 15, 2012, 02:46:53 AM »

When installed on a NMO mount, the antenna you mentioned looks like it will defy the laws of physics and will be mounted on very thin auto sheet metal. Good luck. You will need it!  Wink
« Last Edit: January 15, 2012, 11:19:39 AM by KI4SDY » Logged
K3GM
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Posts: 2549




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« Reply #9 on: January 15, 2012, 03:49:46 PM »

Well, I just ordered an NMO mount and an adapter. Do you think that it won't be structurally sound enough to support the large antenna (Hustler CG-144) I'm putting on the mount?
I'm a firm believer in the use of NMO mounts.  They're a commercial standard, and I believe are better than any other mount, and that includes magnetic mounts.  That said, I would absolutely NOT recommend using an NMO mount in combination with the Hustler CG-144.  I assure you that it will only be a matter of time until either wind load, or a low hanging branch rips the mount from the sheet metal.  The mount that comes (or use to come) with the '144 is a robust trunk lip mount.  Any antenna that's built with a heavy, stiff lower section has the potential to destroy a sheet metal roof. Roof mounted NMO antennas should limited to 1/4 wave whips, or Lasen style 5/8 wave or dual band antennas.
« Last Edit: February 02, 2012, 05:57:42 PM by K3GM » Logged
N6AJR
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Posts: 9930




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« Reply #10 on: February 02, 2012, 11:47:56 AM »

Although they don't specify it, you can almost see it in the picture of the mount, the diamond 400 mount goes on the side of the trunk lip, not the part by the rear window. The mount is strong on the "long" direction, but very bendy on the "short " direction.  If you are using short little 1/4 wave whips on 2 m / 440 etc it really doesn't matter but for a larger antenna it must go on the side of the trunk lid, not the part by the rear window.

I use an atas 120 on my dimond k 400 c mount ( pl259 style) and I use a piece of monofilimint line fro the top of the fat coil to the little hook in the rear for hanging up clothes in the car.  this takes a lot of the backwards push fro the wind off the mount.   Als  run a good groound strap from the  ground side of the antenna to the "car" side of the trunk hinge. The trunk will "float" up and down on the hinge while in motion and the pivot pins make a poor connection so I ran a braided jumper from the shield side of the mount, to the bolt on the car side of the hinge.

I have not had a problem with the mount and its been on there 4 or 5 years...
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