HF Mobile antenna for NMO mount?

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SCPD

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Just a random question, but has anyone seen or heard of a HF antenna for a NMO mount? Is there a specific reason against using this kind of mount for HF...?


-Nick
 

jhooten

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I have put a 3/8-24toMNO adapter on and use Hamsticks BUT only while stationary. The NMO has to be in a very strong mount to take the torque of an antenna that long at anytihing over parking lot speed. Let the antenna hit a solid object and it will rip the NMO out of normal autobody sheet metal.
 

specman

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Like the previous poster said regular car sheet metal just isn't up to the load that a typical HF antenna will place it (considering wind and strikes for instance). Having said that it is possible to obtain "thick" NMO mounts that would permit the use of a backing plate to reinforce the mount. You could then use a 3/8 stud to NMO adaptor as already suggested.

I haven't personally seen an HF antenna made for an NMO mount though.
 

zz0468

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An NMO is essentially a sheet metal mount. An HF antenna, particularly lower frequencies are going to need to be loaded somehow. HF mobile antennas are generally base or center loaded. By this, I mean inductance is generally added to tune out the capacitive reactance of a shortened antenna.

Base loading can be accomplished with a relatively low (spell that small) value of inductance, but it's horribly inefficient. Center or top loading is is more efficient, but is far more demanding of the mounts mechanical strength, which is compromised, being on sheet metal.

So, it's conflicting requirements that lead manufacturers away from NMO mounts for HF.
 

NDRADIONUT

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Maxrad ( If They Are Still In Business ) Made A Base Loaded Antenna Series Starting At 25 Mhz If You Get One Get The Non Dc Grounded Version.
 
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