Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
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
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Thru-the-roof NMO mount vs NMO Magnet mount....  (Read 6699 times)
APW19562
Member

Posts: 46




Ignore
« on: August 07, 2013, 07:39:21 PM »

Someone please school me on the difference here.

I am using the exact same antenna (Tram 1180).

After installing a thru-the-roof NMO mount in my Tahoe... the signal strength and audio clarity have both improved dramatically over the magnet base.

Is the antenna seeing a better ground plane now ?

I tried using a smaller, 19" antenna first (0db gain), but it doesn't hold a candle to the Tram(3db gain).
The Tram 1180 seems to be a darn good antenna.
Logged
W9GB
Member

Posts: 2626




Ignore
« Reply #1 on: August 07, 2013, 08:33:54 PM »

Art -

TRAM-Browning is an OKLAHOMA based company that wholesales and imports
a number of OEM antennas for CB and VHF/UHF from Eastern Asia (China, Indonesia, Mayalsia, etc.)
http://www.trambrowning.com/
524 Westland Drive
Edmond, OK
(405) 359-8243

WHOLESALE RADIO d/b/a Tram-Browning
757 Enterprise Drive
Edmond, OK. 73013-3671

Tram-Browning Inc in Edmond, OK is a private company categorized under Wholesale Radio Communication Equipment and Systems.  Our records show it was established in 1989 and incorporated in Oklahoma.

The Thru-Hole mount electrically ties the coaxial shield to your truck's metal roof.
SO, you have a conductive radial field (efficient).

Magnetic mounts can not do this, as effectively.  They are used for temporary, portable needs.

TRAM 1180 is a dual-band VHF/UHF mobile antenna.
http://www.trambrowning.com/index_files/page-10.pdf
« Last Edit: August 07, 2013, 08:46:18 PM by W9GB » Logged
APW19562
Member

Posts: 46




Ignore
« Reply #2 on: August 08, 2013, 04:20:27 AM »


The Thru-Hole mount electrically ties the coaxial shield to your truck's metal roof.
SO, you have a conductive radial field (efficient).

Magnetic mounts can not do this, as effectively.  They are used for temporary, portable needs.


Well, whatever the case may be... I am a believer now. I will be putting holes in the roof of every car I own or buy now. (Except the Corvette)  Grin
Logged
AE5QB
Member

Posts: 269




Ignore
« Reply #3 on: August 08, 2013, 06:16:26 AM »

Holes are better from an electrical RF standpoint.  My concern is that today's vehicles are made of such thin/flimsy material that there is a lack of strength around the hole.  Hit a few branches with the antenna and you may find a much larger hole than you started with.  I have thought about putting a hole in the top of my F150 but the metal up there is really really easy to press in.  I fear it is just too thin to provide adequate strength.  I have thought about putting a 6 x 6 or 8 x 8 aluminum plate under the hole to give it more support but that would be a job to install.  The mag mount on the other hand, has a 5" diameter support base so it spreads that stress out over a larger area.  It doesn't couple as good but it gives more support and should it hit a branch it will come loose before the roof gives out.  On the other hand, when it does come loose there is a lot of mass bouncing around on the roof top and coming over the side to meet with glass and other parts of the vehicle.  On second though, I think I'll make a mount and attach it to my bumper.
Logged
K7RBW
Member

Posts: 398




Ignore
« Reply #4 on: August 08, 2013, 06:34:05 AM »

I understand where AE5QB is coming from. I put an NMO in the roof of my RAV4 and it's pretty thin. I currently have a 12" antenna on it, which isn't the most effective, but it's better than a mag mount and it fits in the garage. I have some taller antennas but after seeing how flimsy the roof is, I decided not to put anything up there that doesn't have a spring base. I've heard of people putting the mount through large washers and plates under the roof to help stiffen it--something I haven't tried, but might be worth considering.
Logged
N2MG
Administrator

Posts: 0



« Reply #5 on: August 08, 2013, 11:36:12 AM »

Quote
I will be putting holes in the roof of every car I own or buy now. (Except the Corvette)

You're not getting a ground plane on the 'vette anyway!
Logged
WB0KSL
Member

Posts: 94




Ignore
« Reply #6 on: August 08, 2013, 12:07:34 PM »

A couple of weeks ago we lost power at home just as we were leaving for dinner with friends.  Garage door wouldn't open, except manually, of course.  It didn't want to stay in the "up" position, so my wife held it up while I backed out. She insisted she would watch to be sure my 2m/440 antenna mounted on a through the roof NMO mount on the SUV would clear.  She didn't and it didn't.   Smiley  Scraped the antenna and mount right off.  Damage now repaired, and a new antenna is mounted on the hatch back with a Diamond K400 mount installed.  I'm sure it's not as efficient as the roof NMO, but it will clear anything the car roof clears...  Sometimes, the enemy of good, is "better".  I'm happier now, and that's all that counts to me.

73 de wb0ksl, John
Logged
M6GOM
Member

Posts: 945




Ignore
« Reply #7 on: August 09, 2013, 09:19:30 AM »


After installing a thru-the-roof NMO mount in my Tahoe... the signal strength and audio clarity have both improved dramatically over the magnet base.

Is the antenna seeing a better ground plane now ?


Yes.
Logged
K5BBC
Member

Posts: 24




Ignore
« Reply #8 on: August 13, 2013, 10:24:41 AM »

My concern is that today's vehicles are made of such thin/flimsy material that there is a lack of strength around the hole.  I have thought about putting a hole in the top of my F150 but the metal up there is really really easy to press in.  I fear it is just too thin to provide adequate strength.

I don't know which F150 model you have. I just put 4 in the roof of my F150 Supercrew. The middle position is holding the 1/4 wave VHF. I was going to put the dual bander there, but had the same thought you did about the metal thickness and support. I have no concerns about it being able to support the 1/4 wave.

The metal over and ahead of the 3rd brake light and bed light is the most rigid area of my roofline. I installed the dual band there. 1:1 vswr and seems to work fine. I have seen several F150s with various antennas over the light. I can send a pic if you like.
Logged
KD4LLA
Member

Posts: 462




Ignore
« Reply #9 on: August 17, 2013, 07:25:11 PM »

It didn't want to stay in the "up" position, so my wife held it up while I backed out. She insisted she would watch to be sure my 2m/440 antenna mounted on a through the roof NMO mount on the SUV would clear.  She didn't and it didn't. 

73 de wb0ksl, John

I wouldn't trust that door w/ the opener working then.  Any O/H door *should* be adjusted to be "neutral" in the up position.  Better call whomever installed it back...

Mike
Logged
K1DA
Member

Posts: 513




Ignore
« Reply #10 on: August 18, 2013, 02:28:59 PM »

   You are using a Larsen Communications mount, it appears, I'd use a LARSEN antenna to go with it.  Larsen probably has the biggest share of the commercial and public service  two way market, and they supply spare parts from stock. I use a dual band Larsen ( 2 and 440) that fits the single stud Larsen mount.  It's only 17 inches tall. 
Logged
K6CPO
Member

Posts: 157




Ignore
« Reply #11 on: August 20, 2013, 05:48:09 PM »

A couple of weeks ago we lost power at home just as we were leaving for dinner with friends.  Garage door wouldn't open, except manually, of course.  It didn't want to stay in the "up" position, so my wife held it up while I backed out. She insisted she would watch to be sure my 2m/440 antenna mounted on a through the roof NMO mount on the SUV would clear.  She didn't and it didn't.   Smiley  Scraped the antenna and mount right off.  Damage now repaired, and a new antenna is mounted on the hatch back with a Diamond K400 mount installed.  I'm sure it's not as efficient as the roof NMO, but it will clear anything the car roof clears...  Sometimes, the enemy of good, is "better".  I'm happier now, and that's all that counts to me.

73 de wb0ksl, John


Aren't most NMO mounts threaded?  Wouldn't it have been easier to just remove the antenna?  I have an NMO mount and the same Tram 1180 antenna as the OP on my truck and even though I don't have a garage, I always remove the antenna and put one of the TRAM caps over the mount when I park the truck.  If I have to go into a parking garage, I just stop at the entrance and unscrew the antenna.
Logged
APW19562
Member

Posts: 46




Ignore
« Reply #12 on: August 21, 2013, 07:21:54 AM »

I actually removed the Tram 1180 again and replaced it with the thin, flexible 19" 1/4 wave antenna...

The signal loss was a small sacrifice... in order to prevent damage to the roof sheetmetal. My wife drives the Tahoe 95% of the time and I'm sure if I leave the 37" Tram on the roof, she will have it ripped-off or bent over in no time.  Grin
The smaller 19" antenna is thin and flexible enough that I can almost fold it flat against the roof without damaging it.

It's easy enough to screw the 1180 back on if I plan any trips or extended time in the Tahoe myself. The little 19" antenna does pretty good for what it is.
Last simplex contact I had was a solid 7 miles away and was crystal clear, solid signal.
Logged
WB0KSL
Member

Posts: 94




Ignore
« Reply #13 on: August 21, 2013, 04:21:24 PM »

A couple of weeks ago we lost power at home just as we were leaving for dinner with friends.  Garage door wouldn't open, except manually, of course.  It didn't want to stay in the "up" position, so my wife held it up while I backed out. She insisted she would watch to be sure my 2m/440 antenna mounted on a through the roof NMO mount on the SUV would clear.  She didn't and it didn't.   Smiley  Scraped the antenna and mount right off.  Damage now repaired, and a new antenna is mounted on the hatch back with a Diamond K400 mount installed.  I'm sure it's not as efficient as the roof NMO, but it will clear anything the car roof clears...  Sometimes, the enemy of good, is "better".  I'm happier now, and that's all that counts to me.

73 de wb0ksl, John


Aren't most NMO mounts threaded?  Wouldn't it have been easier to just remove the antenna?  I have an NMO mount and the same Tram 1180 antenna as the OP on my truck and even though I don't have a garage, I always remove the antenna and put one of the TRAM caps over the mount when I park the truck.  If I have to go into a parking garage, I just stop at the entrance and unscrew the antenna.

Sure, that would have been much easier!  But we were late, it was storming.  We took the lazy way out.  Not the first dumb thing I have done, and judging from other dumb things I'm doing as I get firmly into my "senior years", it won't be the last.  What I have now is working well enough to please me, and is a bit more idiot proof.  Like I said, I'm happy.  Mobile is a compromise, no matter how you cut it.  Finding the sweet spot of performance versus convenience for each individual is the secret.  I have had problems with low tree limbs out on the farm in the past.  Alan, K0BG, would not find my setup very impressive, but then he lives in Roswell, NM, about 300 miles from the nearest tree (remember trees from your days in Kansas City, Alan?   Smiley

Wishing my memory was better,
73 de WB0KSL, John
Logged
KD8RFT
Member

Posts: 29




Ignore
« Reply #14 on: August 23, 2013, 08:35:21 AM »

My concern is that today's vehicles are made of such thin/flimsy material that there is a lack of strength around the hole.  I have thought about putting a hole in the top of my F150 but the metal up there is really really easy to press in.  I fear it is just too thin to provide adequate strength.

I don't know which F150 model you have. I just put 4 in the roof of my F150 Supercrew. The middle position is holding the 1/4 wave VHF. I was going to put the dual bander there, but had the same thought you did about the metal thickness and support. I have no concerns about it being able to support the 1/4 wave.

The metal over and ahead of the 3rd brake light and bed light is the most rigid area of my roofline. I installed the dual band there. 1:1 vswr and seems to work fine. I have seen several F150s with various antennas over the light. I can send a pic if you like.

I have a 2004 F-150 Supercrew and my Larsen 270 NMO through the roof is mounted a few inches forward of the third brake light. I get fantastic performance out of this antenna install. Extremely happy with the setup.
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!