NMO Mount...Or...

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ThomasMcKean

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Where can I get the bottom part only of an NMO antenna so I can build my own? I want to build an antenna with an NMO mount. I have found them for 2/8-24, but not for NMO? Is there a place I can order? :)
 
mmckenna

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I think you are referring to the antenna base, right?
I've never seen them sold separately, other than the separate coils that you mount the whip to. Your best bet might be to buy a Larsen NMO-Q quarter wave antenna, and just reuse the base for what you want. Probably cost you $15 bucks total.

If I recall correctly, the top stud is 5/16 x 18 thread.
 
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mrweather

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That's a good suggestion. I did just that for a shortened CB antenna I made many years ago (when I didn't want to use the bigger NMO27 coil and 49" whip).
 
RadioPatriots

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If I understand your question correctly, Antenna Farm has quite a few of them, both drill/hole and magnetic. Or I assume you only want the part that would normally be at the bottom of a NMO antenna.

NMO Mounts

EDIT: Universal Radio also has a NMO to SO239 mount/adapter, if you want to build from that.

NMO to SO239
 
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RadioPatriots

RadioPatriots

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There's no need to keep the 239 connector. This is a DYI project. He can either utilize the 239 connector, or scrap the 239 and cannibalize this adapter for the NMO base, or another antenna with a NMO base.

As far as things not being waterproof ... then make them waterproof.

There are so many ways it could be done. Some of them permanent, others not. If he uses the NMO/SO239 adapter as-is, he could terminate his antenna with a male 239 connector. However the connection would be enclosed in a larger non-conductive conduit, complete with appropriately drilled and reinforced end-caps, that could be fully weatherproofed at the top (since that will not change) but temporarily weatherproofed for the bottom, and fit snugly over the base so as to be near flush with the bottom ... possibly with the addition of inner o-rings and/or silicone for weatherproofing. A better way might be to use conduit, same diameter as the adapter base, that would seat snugly against the top of the adapter when screwing down the 239. Again an o-ring could be used. The 239 connector would be the antenna's connection and main strength. This would allow for experimenting with multiple antennas with one base. Or of course it could be made permanent.
 
mmckenna

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ThomasMcKean said:
Yew'd think what with all the hams building stuff there'd be an NMO version?
Click to expand...
I was wrong. It's not 5/16 x 18 thread. It's 5/16 x 24.

Any machine shop could easily fabricate a 5/16 x 24 to 3/8 x 24 adapter in short order. Someone good with a drill press and a tap/die set could make one for you. You'd probably want to keep the overall length short, since I'm not sure the NMO mount would last with a tall rigid antenna on it. One branch or parking garage strike and you'd damage something. Might need to design in a breakaway or spring.
 
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