NMO Mounts and Wind Loading

[jcrmadden]

Hello everyone. My name is Ray and I'm an Antennaholic.

Hello Ray...

It's been four days since my last antenna purchase.

**Scratches neck nervously**

Seriously, I have more antennas than I have underwear, and all but two are are on Breedlove QD's for a "quick fix"

The wife's Yukon still doesn't have a permanent mount, but I picked up a NMO27B and W640B in preparation (because why not).

"I can stop anytime I want! Okay?!"

Then I found the NMO to 3/8x24 adapter and why wouldn't I expand the antenna options (addiction) to both vehicles?

Antics aside, my real question is, "How much wind loading can an NMO mount really take?"

 

[mmckenna]

The wife's Yukon still doesn't have a permanent mount, but I picked up a NMO27B and W640B in preparation (because why not).

You'd want the NMO-34 coil if you are going to use the 64" whip, not the NMO-27 coil.

Then I found the NMO to 3/8x24 adapter and why wouldn't I expand the antenna options (addiction) to both vehicles?

Antics aside, my real question is, "How much wind loading can an NMO mount really take?"

Not sure anyone could accurately answer that since it will depend on the vehicle that its been installed on.

But, it'll have no issues running an NMO-27 at 80+ mph. Done that through Texas on an aluminum body Ford pickup.
Worst case, I had a stiff Larsen NMO quarter wave wide band antenna that has a very thick/stiff whip with a spring at the base. Got into a low clearance situation that resulted in the whip getting folded back 90º. Zero damage to the truck roof, zero damage to the NMO mount, spring took a permanent kink.

Properly installed NMO mounts are solid. Improperly installed, all bets are off.

Not sure I'd want to run a 3/8x24 antenna on there without a good spring. Most of those fiberglass antennas are not forgiving. And I'd not run a full 108" whip, either.

And I've done a lot of NMO mounts over the years, including lots on vehicles at work. Never had an issue with them with normal NMO mount antennas.

 

[prcguy]

Hi Ray, I can stop at any time too and probably attend meeting across town from you. Not that they are helping.

I've played with NMO to 3/8" adapters and they would be scary to use with most any fiberglass CB whip over 2ft or with a lightweight center load longer than about 3ft putting a lot of stress on the vehicle sheet metal. I use them on temporary base station adapters and for simply checking SWR on some antennas without actually driving around.

Do yourself a favor and buy another antenna, it will make you feel good as you ponder your final decision.

 

[RFI-EMI-GUY]

Hello everyone. My name is Ray and I'm an Antennaholic.

(snip)

Antics aside, my real question is, "How much wind loading can an NMO mount really take?"

A heck-of-a-lot

What is the top speed of a 98-11 without limiter?
by u/redditreset86 in CrownVictoria

 

[slowmover]

I once was running 90+ and easily 12-14k over gross in oilfield days leading a group westbound out of Galveston on the 600-mile drive to Monahans, TX. At about where the speed limit opens up to 80 on IH-10.

Almost had a heart attack when a DPS trooper was coming up alongside. He had to be at over 100-MPH.

I’d have noticed if any critters escaped from the antenna farm. Eagle-eyes, as I was waiting for him to pull over the bunch of us. To start the downshifts timed perfectly to plan:

It was gonna be tricky to come down s-m-o-o-t-h-l-y being that heavy and not get rear-ended . . . so as to not reveal how far over we were. Didn’t have the overweight permits for that part of the state.

Those AWD DODGE Chargers were speed-limited at either 140 or at the 155-MPH Autobahn limit. The early ‘70’s A38 DODGE Police Pursuit could cruise at 120+, but I can’t remember seeing NMO-type on them.

So git’er up past 90, drop it in the big hole and let it start that just perceptible side-to-side rock afore you check the mirrors to see what’s gaining on ye.

If he’s a’coming on that Dodge will still be up-and-down as long as he’s got his foot in it.

Frequency Shift Inbound.
.

 

[slowmover]

I was running these on the Peterbilt West Coast mirror arms. Never worried about whip flex, but they were on BIG six-bolt, fully-threaded mounts.

That was the point where I’d added the DSP Speaker. Got out and back in excess of thirty-miles a few times once out near Fort Stockton.

Until you asked it, it hadn’t occurred to me to question whether an NMO34 + WD640 was in peril at 100-MPH.

.

 

[jhooten]

VHF NMO-Q Center mounted on the roof of the race car at a little over 140with a 20 mph head wind. It bent a little at 120 in a heavy rain storm (yes, we raced in the rain).

 

[prcguy]

I once was running 90+ and easily 12-14k over gross in oilfield days leading a group westbound out of Galveston on the 600-mile drive to Monahans, TX. At about where the speed limit opens up to 80 on IH-10.

Almost had a heart attack when a DPS trooper was coming up alongside. He had to be at over 100-MPH.

I’d have noticed if any critters escaped from the antenna farm. Eagle-eyes, as I was waiting for him to pull over the bunch of us. To start the downshifts timed perfectly to plan:

It was gonna be tricky to come down s-m-o-o-t-h-l-y being that heavy and not get rear-ended . . . so as to not reveal how far over we were. Didn’t have the overweight permits for that part of the state.

Those AWD DODGE Chargers were speed-limited at either 140 or at the 155-MPH Autobahn limit. The early ‘70’s A38 DODGE Police Pursuit could cruise at 120+, but I can’t remember seeing NMO-type on them.

So git’er up past 90, drop it in the big hole and let it start that just perceptible side-to-side rock afore you check the mirrors to see what’s gaining on ye.

If he’s a’coming on that Dodge will still be up-and-down as long as he’s got his foot in it.

Frequency Shift Inbound.
.

In the mid to late 70s I worked at a CB/car stereo shop in Colorado Springs and had to go to a radio convention in Denver for CB stuff once. A friend drove me in one of these Smokey and the Bandit things and we stuck a new Turner mag mount CB antenna on the roof between the T tops and did about 125mph most of the way from north Colorado Springs to Denver and the mag mount was fine. Turner was one of the vendors at the show and after telling them about our trip it became part of the sales pitch for their mag mount antennas.

 

[jcrmadden]

You'd want the NMO-34 coil if you are going to use the 64" whip, not the NMO-27 coil.

🐳 💩

Looks like I need to pick up an nmo34 and a 49" whip to fix the mismatch (and have another antenna).

 

[mmckenna]

🐳 💩

Looks like I need to pick up an nmo34 and a 49" whip to fix the mismatch (and have another antenna).

@jcrmadden Sorry, typo. You want the NMO-30 coil.

 

[K6GBW]

The LASD puts NMO mounts on an Eurostar AS350 that tops out around 178 MPH and they're fine.

 

[W5TXP-Peter]

VHF NMO-Q Center mounted on the roof of the race car at a little over 140with a 20 mph head wind. It bent a little at 120 in a heavy rain storm (yes, we raced in the rain).

Sounds like a fun time.
When were you in the 56th FA? I was there from '76-'80 - HHC, 2/4 Inf Regiment, 56th FA (Pershing) - Wilkins Kaserne, Kornwestheim, FRG

 

[jhooten]

Sounds like a fun time.
When were you in the 56th FA? I was there from '76-'80 - HHC, 2/4 Inf Regiment, 56th FA (Pershing) - Wilkins Kaserne, Kornwestheim, FRG

HHB 3/84 76-78 and 80-82

 

[niceguy71]

I, ..... luckily don't have a CB antenna addiction....
but HONESTLY my "dealers van" *AKA Amazon* was in the neighborhood today, and yelled hey kid you gotta try this totally radical Sirio 5000 Performer smuggled in from Italy!!!.... I had no parents or teachers around to stop me.... so in my weakened state from no CB for 3 weeks.... I bought it!

I just got back from a 3 week vacation and all I thought about was comparing my Tram 3500 to my K-40 mag mount and to my Stryker SAR-10 mag mount..... then I thought.... oh hell I may as well get the Sirio 5000 performer... so while sitting in the airport bored and dreaming about making my "ultimate antenna comparison youtube video"..... I bought it....

so as soon as the weather gets a little warmer ( teens this week) I'll adjust the SWR on all of them in my back yard and then on the next good CB conditions night.....
I'm going to go to the Texas Road House ( 10 miles from the house) then lay my everyday Tram 3500 down in the bed of the truck and run the coax of my spare Tram 3500 through the rear sliding glass window and onto the roof of my F150 and give it a 10 count.... then do it with the K-40 then the Stryker SAR-10 and finally the Sirio 5000 performer.... I will run the coax the exact same way on all the antenna's the same way and place them all in the same place on the roof of the truck.... then go home and see what gives the most signal strength and what sounds the clearest and loudest.

with that said I bought the Stryker SAR-10 over a year ago to compare it to my Tram-3500...... and have yet to do it!... but I will try to make it happen very soon.

I just got the Sirio today and have not opened it.. the box is bent like a hockey stick... hope it's ok.
I just went to take the picture so I opened it... looks ok

 

[slowmover]

Looked up that product SKU. I think you’re gonna love it. SIRIO is great! Paul Revere coulda used that light in the night.



Wondered where you were. Glad to hear it was a vacation. They’ll know you’re back!

.

 

[niceguy71]

Looked up that product SKU. I think you’re gonna love it. SIRIO is great! Paul Revere coulda used that light in the night.

View attachment 176477

Wondered where you were. Glad to hear it was a vacation. They’ll know you’re back!

.

Vacation was good.... I was in four countries... it was my present to myself for retiring a couple years ago.... now I just want one more Cruise to Hawaii....
this last cruise I told the captain to take 20 minutes and grab a coffee... he didn't let me... little disappointing.
then they over booked one of my excursions by 7 people!!!! we were pissed but luckily a native near by heard we couldn't go on the excursion and saw my skippers hat and offered to let me use an old ship he had, and he even told me where an uncharted deserted island was... how lucky can you get huh? so I took the other 6 passengers for a 3 hour tour....... don't even get me started with how that worked out.

and slowmover you know I would never buy that goofy antenna..... but it does say Fighter on the bottom??? not performer??? but I guess all the Sirio's say that if you get them in red?

 

[slowmover]

That was payback for:

With heavy heart I post this

I'm posting this with a heavy heart.... As much as I love playing my CB radios and equipment .... filming my range tests..... doing my adjustments and tuning, DXing and everything that comes with it. this is taking up too much of my time. This has caused family problems and work problems. I am...

forums.radioreference.com

.

 

[niceguy71]

That was payback for:

With heavy heart I post this

I'm posting this with a heavy heart.... As much as I love playing my CB radios and equipment .... filming my range tests..... doing my adjustments and tuning, DXing and everything that comes with it. this is taking up too much of my time. This has caused family problems and work problems. I am...

forums.radioreference.com

.

I loved that post