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Username: Tech833

Post Number: 1816
Registered: 8-2002
Posted on Saturday, February 13, 2010 - 11:14 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Wilson FGT-5 antenna review by Tech 833

‘Trucker’ style antennas are those having a 3/8 inch, 24 thread stud and typically fall into one of two categories- Helical fiberglass, like the popular Firestik, and base or center loaded metal. Fiberglass antennas offer flexibility and vibration resistance, as well as lower cost. Metal antennas offer greater power handling capability and bandwidth.

The WilsonFGT-5, 5-foot Silverload antenna is built like the popular Firestik antennas using enameled copper wire wound around a flexible fiberglass rod and covered with a heat-shrink plastic sleeve. Unlike the tunable Firestik antennas, the Wilson also has a metal ferrule at the top with a setscrew holding a short metal whip. This arrangement allows fine tuning the length and resonant frequency of the antenna.

One thing you will find unusual about the Wilson 5-foot Silverload antenna is a short piece of insulated wire sticking out the bottom of the plastic cover. This wire connects to a small coil at the bottom of the antenna and is only used if the installer has difficulty obtaining a low SWR. Connecting this wire to ground will lower the resonant frequency of the Wilson 5-foot fiberglass by about 400 kc. Otherwise, it is unused and can be removed if desired. In my installation, I chose to keep the wire intact, but used a small plastic tie wrap (zip tie) to hold it out of the way (see photo).

The Wilson 5-foot Silverload antenna cover is a UV stabilized plastic that is highly scratch and nick resistant. There is also a rubberized end cap that is used to cover the metal tuning tip after it is tuned. Keeping the antenna elements covered and sealed also makes for a quieter antenna. Be warned- once the rubberized cap is installed, it is almost impossible to remove it later.

I experimented with the Wilson 5-foot Silverload on a few different vehicles to measure the bandwidth and power handling capability. I had a little trouble tuning the Wilson 5-foot fiberglass for the very bottom edge of the 10m amateur band so I could legally use up to 1500 watts of power for some real-life on air testing. Although, since the Wilson 5-foot Silverload is only rated for 1000 watts maximum, I never got anywhere near the limit of my equipment anyway.

The Wilson 5-foot Silverload (and others like it) are notoriously very high Q antennas, since the antenna is basically almost a continuous coil. This does limit the overall bandwidth of the antenna compared to some of the large-coil types and the 9 foot whip. However, the Wilson 5-foot antenna’s bandwidth is better than the popular Firestik. In my tests, the <2:1 bandwidth of the Wilson is about 1.2 MHz.

In all but one of my installations, a low SWR was quick and easy to obtain. The Wilson 5-foot fiberglass is not very picky about coax cable length like some other ‘trucker’ style ungrounded type antennas (if it gets picky in your installation, try grounding the short wire stub). A nearly perfect 1.2:1 SWR in the center of the CB band would give a 1.3:1 to 1.4:1 SWR on the outer edges in almost every installation I tried.

When at highway speeds, the Wilson 5-foot Silverload antenna bends very little, with the top deflecting only about 10 degrees from vertical at 65 MPH. Yet, the antenna is still plenty flexible to resist breaking if struck by a low tree limb. Of course, if you strike that same tree limb while moving at highway speeds, the antenna will probably disintegrate.

On-air testing showed better performance in both transmit and receive over a Firestick. On the antenna test range, gain was measured at -2.9 dB compared to ˝ wave dipole antenna. This is good considering the 3-foot Firestik has -5.1 dB dB gain. That is also slightly better than the center loaded metal Wilson 5000 Trucker antenna which has a -3.1 dB gain. That equates to a +0.2 dB improvement over the 5-foot long Wilson 5000 Trucker. The Wilson 5-foot Silverload antenna has exactly the same measured gain on the horizon as the Monkey Made MM9 and the K40 BCMAX large-coil antennas, and isn’t nearly as ugly (according to my wife).

For those running a medium or large power amplifier, the fiberglass antennas aren’t for you. The drawback with most all of the fiberglass helical antennas is the RF current makes the coiled wire get warm, and eventually builds enough heat to cause the antenna to fail. Running 100 watts in CW mode (carrier power), the Wilson 5-foot Silverload s shows little signs of heat buildup. Once the amplifier was turned up to 500 watts, there were signs of warming, although not yet worrisome. At 1000 watts, the Wilson 5-foot Silverload will get warm pretty quickly, and it was obvious that this power level is just a bit too much for this antenna for any length of time. If you do have anywhere near 1000 watts, keep your transmissions short! At 500 watts, a typical 2-way conversation should be safe. Long transmissions should be avoided.

I tried adding a 4-inch heavy duty spring to the Wilson 5-foot Silverload fiberglass antenna on my utility truck. The heaviest duty spring is still not strong enough to hold the antenna vertical much over about 30 MPH. At highway speeds, the antenna lays down to almost 45 degrees. Someday, someone needs to sell a ‘heavier duty’ heavy-duty spring! Most people don’t use a spring with the fiberglass antennas anyway since they are already very flexible on their own. Assuming your mount is strong enough to handle it, minor bumps won’t bother this antenna.

The fit and finish of the Wilson 5-foot Silverload antenna is very impressive. You can tell that there is attention to detail and quality control in play. Wilson even includes a small O-ring on the 3/8 inch threads to help keep water out of your antenna stud. That will help cut down on corrosion.

The Wilson 5-foot Silverload beats the Firestik and the K40 fiberglass antennas hands-down. If you are running a legal power CB radio in your rig, the Wilson 5-foot will give you maximum performance in a fiberglass antenna.

-Tech 833

Your radio 'Mythbuster' since 1998