The Larsen NMO27 antenna was strictly designed for commercial use in the 27 – 30MHz range. It was never designed for amateur radio use, or for long distance ground wave or DX applications. It was designed to provide a good, robust antenna for commercial mobile applications such as logging and mining operations. The 49” whip is perfect for trucks that can’t handle longer whips, and it provides a robust compromise. The Larsen NMO27 is a commercial low-band antenna, and as such was designed to be robust and easily field replaceable. It is a compromise. It was designed to allow trucks to communicate with a remote base within ground wave range. It is entirely unsuitable for amateur (or CB) use.
Here is what we use instead – the Larsen NMO34 system. The Larsen NMO34 system uses the Larsen NMO34 coil, a 64” whip and a spring to provide a high efficiency and high performance antenna that compares favourably to the Wilson 1000 series. The total length of the antenna is approximately 70”. It works exceedingly well, and with over 15 users locally in the Ottawa area, we have rave reports and excellent results.
The antenna is NOT normally commercially available, but must be custom ordered . You will need the following parts: the NMO34 coil (NMO34B) the 64” whip (W-640B) and the spring (SPRINGB). This can be ordered from any Larsen dealer.
Finally, it is compatible with all Larsen NMO mounts, so you can swap it out with any Larsen NMO-type VHF antenna.