Review: K40 CB Antenna Short Cuts

Author: Phil Hansford, June 6, 2000


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The K40 is my latest in a long line of CB antennae

One of the first things I did when I got my first four wheel drive years ago was buy a CB radio. At the time I simply wanted an antenna that was easy to mount, and relatively cheap. I settled upon a Radio Shack "gutter Mount", which I mounted above my passenger door. Aside from the spring bouncing the mast violently every time I hit a bump, the longest range I could get was about a half kilometer (0.3 miles). After water got in the spring and rusted the ground, I tried various other setups, including:

Finally, I decided to try the K40, from K40 electronics. Here are my impressions...

The Antenna:


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Upper half of the K40
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Lower half of the K40

The K40 has an integral trunk lip mount, and includes a 5 foot flexible stainless steel whip, and an 18 foot shielded cable assembly with removable connector. The coil assembly is contained in a plastic, two-piece base, with a great security feature: A quarter-turn of the coil/whip assembly separates it from the base mount, allowing you to quickly remove your antenna for security, low overhangs, or that annual trip to the mall.

The base rotates up to 30, to keep the mount vertical, and can also be mounted "through the roof" or on the optional "Magnamount" bracket.

The K40 comes with a 30 day money-back performance guarantee, and a full 5 year quality guarantee.

The Mount

Mounting the K40 on a Montero is quite simple. This antenna has several mounting options, including a strong magnet mount, and a mirror

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Removing the coil is as easy as...
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...twist and pull away from the base

mount, but the included lip mount worked just fine (bear in mind that in most cases, the higher your antenna is mounted, the greater your radio range, but for going through low overhanging trails, etc., the hood lip works adequately).

Before running the cable, determine where the antenna is to be mounted. I put mine on the driver's side hood lip. The adjustable base allowed me to level it out, and then I tightened the two allan-head set screws onto the underside of the hood-lip (a rubber pad sits between the antenna base and the paint on your hood!).

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Tuning the antenna

The cable is also easy to install, since the large connector unscrews, and you can easily poke the cable through a firewall grommet, before reattaching the the connector to the cable, and then to your CB unit.

Before trying the K40, I used a meter to set the SWR (standing wave ratio) to an acceptable level. This was easily accomplished by loosening the set screw at the base, and raising or lowering the mast until the SWR of channel 1 and 40 were equal. Once installed and tuned, I was ready to try it out!

Transmission Time!

I drove on the highway with the K40, where the flexible whip arced in the wind to about 35 from vertical, and made a slight whistle, but was barely audible over my Monty's slippery aerodynamics. The range was quite impressive; with a Radio Shack CB (limited to 4 watts in Canada) I increased my range from less than 1 kilometer to over 6 (This was not a scientific test, but merely subjective, based on experience with   previous setups). In city driving, my range was still around 3-4 kilometers, depending on the topography and radio traffic.


Though cell-phones have surpassed CB's as the prime source of vehicular communication, there are times, especially offroad, when the CB is still the tool of choice. Armed with a great antenna like the K40, a CB will be in my vehicle for years to come.

  • K40 Electronics 1500 Executive Drive Elgin, IL 60123 (708)888-7200

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