Discussion in 'Mobile Radio Systems' started by KC2ZMY, Jan 8, 2011.
is the 3/8x24 mount the same as the nmo mount
Nope. Similar but not the same. NMO mounts in a 3/4 inch hole. Although it is a bigger hole than the 3/8 mounts, I have found the NMO to work better and be sturdier.
As a retired two-way radio tech, I have installed thousands of NMO mounts, so I think I might be entitled to an opinion on this subject! HI
They are completely different. A 3/8th 24 mount uses a machine screw that is 3/8ths of an inch in diameter with 24 threads to the inch as the antenna connection. The NMO mount was developed by Larsen for Motorola and has now become pretty much the standard mobile antenna mount.
The size of the mounting hole can vary with the 3/8th 24 because the machine screw is only for the connection to the radiating portion of the antenna. This machine screw has to be insulated from the body of the vehicle and that insulation can vary in diameter.
Rob don't forget the 3/8" nmo mount. I use those because the smaller hole leaves more metal for the mount to grip and still gives the good connection and stability of the nmo.
But, the NMO mount that uses a 3/8ths inch hole is NOT a 3/8ths 24 mount. The former is a hole and the latter is a machine screw.
picture and 1000 words...
3/8 24 thread mount
Well, no: They are incompatible and not interchangeable.
On HF (below 30 MHz) a 3/8-24 mount works fine in most situations, if it's grounded properly.
On VHF or UHF, an NMO mount far surpasses the performance of any kind of 3/8-24 mount because it's more efficient and maintains impedance a lot better. NMO mounts are good to about 1000 MHz, while 3/8-24 mounts are good to maybe 30 MHz.
I didn't mean to confuse anyone Glen, but Rob mentioned only the 3/4" nmo. I was just letting the questioner know there were other options in the nmo family.
Sorry for the confusion!