Extreme NMO - Subaru, Silver and the 60" Whip

Can an NMO mobile Mount Handle a Big Whip

NMO mounts are very sturdy and, by inspection, appear capable of staying put in the most severe circumstances.

Can the average NMO though-hole installation and my Subaru Outback roof metal stand up to the torque from a wind-blown 62 inch whip full of phasing coils?

I thought “I’m not sure” and set out to beef up the installation as a precaution.

Read on to learn about my reinforced NMO installation.

Tall NMO Antenna Background

After seeing the results my roving partner had last year during the Virginia QSO Party (VAQP) with the Diamond SG7900ANMO, I purchased one about 9 months ago. I haven’t used it yet, but it’s the whole reason for considering a through-roof NMO mount on my Subaru daily driver. At 62 inches, the Diamond SG7900 is a rather tall antenna, but again, my partner heard folks I couldn’t, and we were almost side-by-side. His was mounted in the center of his land-yacht’s roof; My NMO mount will be towards the back to avoid the sun roof and its machinery.

Tall NMO Antenna Requirements

Install a through-hole NMO mount in the roof of a 2004 Subaru Outback (with two sunroofs – only open/unobstructed metal area near the rear of the roof)
The NMO mount must be able to accommodate a Diamond SG7900 dual-band antenna (62″ tall) at typical driving speeds.
The NMO must replace the current mag-mount, which couldn’t hold up the Diamond, and isn’t all that good for paint jobs.

Step by Step NMO Mount Installation Photo Gallery

Looking between the headliner and roof from the rear; about a 3-4" gap in which to work. — Drop Headliner

Some prep tools and the 16x8 inch reinforcing plate — Shape Reinforcing Metal

Ye olde two part epoxy; this particular type is 'silver conductive' — $ilver Epoxy

Assistant mixes the Silver Epoxy — Mix Silver Epoxy

Mix and spread Silver Epoxy over the plate. — Spread Silver Epoxy

The plate is now in place at the correct location, being held in place by a lever arrangement — Clamp Reinforcing Metal

View of the 'lever arrangement'; a fulcrum, stick, and bucket with two jugs — Lever System to Cure Epoxy

Commitment - the drilling begins. — Drill Pilot Hole

I really like Dewalt tools... — I like Dewalt

Daughter asks for 3rd time if Mom knows I'm drilling a hole in the car. — Cut 3/4 Inch Hole

Drilling Complete — Finished 3/4 Inch Hole

Putting the (Larsen) mount in place - Thickness was a problem. — Install NMO Mount

NMO Ring Ready for Installation. — Add NMO Ring

Add one more beautiful NMO mount to the world. — Finished NMO Mount

And here it is... the 5 foot whip on my new beefy NMO mount. — Diamond SG7900A

NMO Lessons Learned

A hole punch probably wouldn’t have worked with the backing plate in place; The hole saw seems to be a cost-effective way to get a 3/4″ hole in the roof.
I’m not sure about mount performance; More to come after the 2012 VAQP.
The silver epoxy may have been overkill, and may not end up holding as well as I hope; only time will tell on that front.
Being able to remove the headliner would have been handy.
These sorts of tasks always take longer than expected.

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3 thoughts on “Extreme NMO – Subaru, Silver and the 60″ Whip”

Good job! Any update on how it’ s working? Has it stayed put as expected?

Jack – The mount has worked flawlessly since installation, both with the large Diamond antenna and with a shorter Larson I use as a "daily driver." Even with a relatively short car, parking garages (and low hanging tree limbs) have resulted in bent antennas, but the mount is solid. I have a NMO 'cap' that I put on when hauling gear or kayaks on the roof — all in all, I am very happy with this mounting approach.

No flex in the outer skin of the car body ?? That's a lot of wind load …

After everything was done. ??