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Wilson Flex-3 Antenna Installation and Adjustment

I'm somewhat of a fan of the Wilson Flex antenna.  I've been running their 4' model for a couple of years and have had nothing but total satisfaction while doing so. 

I was very pleased to see that Right Channel Radios included a Wilson Flex antenna in their off-road kit.  I had my choice of a 3' or 4' model and chose the 3' length.  Why the shorter one?  As I said, I've ran the 4' for a couple of years and I wanted to see how well the 3' model performed.  Also, I can get my garage door up and down with the 3' model. 

To keep weight at a minimum, the antenna is built on a 1/4" tapered fiberglass rod using 22 gauge silver plated wire and covered with a black polyolefin protective covering.  Not only does this make for a light weight antenna but it makes for a great amount of flexibility.  You should realize that no antenna is bulletproof and those used on the trail will certainly get more abuse than one spending its years going cross-country on a big rig.  That being said, I've found that the more flexible the antenna is, the better survival odds it has.  I'm not a big fan of antenna springs and appreciate the slim and trim appearance of the Wilson Flex antenna design.

With the mount installed, it was time to attach the antenna to the mount.
 

The coupling nut is threaded at both ends and allows the Flex-3 antenna to thread directly into it.  I used a pair of wrenches to gently snug the antenna into the amount.

The Flex-3 antenna comes with a "matching lead", as shown in the above photo, that when attached to a ground, lowers the resonant frequency of the antenna.  I've not found it necessary to use this wire and if you use it when not needed, your performance will suffer badly.  On my Flex-4 antenna, I cut the connector from the end of the wire and then used a length of heat shrink tubing to secure the wire along the length of the antenna.  This kept it out of site and also from touching any metal.  Worked great!  It also allowed me to maintain a functional matching lead should I ever change mounting configurations and find myself possibly needing it.
 

The Flex antenna has an adjustable tip that allows you to adjust the antenna for minimum SWR (stand wave ratio).  A small Allen wrench is supplied (nice touch).  My suggestion for the Allen wrench, after you are done using it, is to put it in a labeled envelope and toss it into your glove box for the next time you might need it.  Just remember where you put it! 

OK....Time to adjust the antenna using the SWR meter supplied in the off-road kit.

The fundamentals of adjusting the antenna are pretty simple.  The goal is to get as low of a SWR as you can.  A ratio of 1 to 1 is perfect.  2:1 is not too bad and one can certainly live with that.  3:1 is the max and I would do some serious work to get mine lower than that if at all possible.  Anything higher than 3:1 means you have problems that require attention and you shouldn't use the radio.

Check your SWR at Channel 1 and then again at Channel 40.  If the SWR is high on Channel 1 and low on Channel 40, then antenna is too short and you need to lengthen the adjustable tip.

If the SWR is high on Channel 40 and low on Channel 1, then antenna is too long and you need to shorten the adjustable tip.

When adjusting the antenna tip, you should move it a very small amount, about 1/8", and then check the SWR again.  In most cases, a small amount of movement can change the SWR more than you might expect.  Moving the tip in large increments may cause you to miss the "low spot" in the SWR curve leaving you with the appearance of something being wrong with your antenna.
 

The SWR meter and 1' patch cable is attached to the radio and to the antenna.  The short patch cable is attached to the RF connector on the back panel of the CB radio while the other end of the patch cable is attached to the radio connector (labeled RTX) on the back of the SWR meter.  The vehicle's CB coax cable is attached to the remaining RF connector on the back of the SWR meter (labeled ANT). 

To check the SWR, place the FWD/REF switch in the FWD (forward) position.  Turn the channel control on the radio to the desired channel and push the push to talk (PTT) switch on the microphone.  With the radio now in transmit mode, do not speak into the microphone.  Keep the PTT switch pushed and adjust the CAL control on the front of the SWR meter such that the needle is aligned with the SET mark on the meter.  With the PTT switch still pushed, change the switch to the REF (reflected) position and read your SWR on the top scale of the meter.  A 1:1 SWR looks just as is shown in the above photo.....the red meter needle is resting on the "1" (far left end of the upper scale).  A 3:1 SWR places the meter needle on the "3" mark at approximately the half scale position.

Every time you change the channel on the radio and check your SWR, be sure to place the switch in the FWD position and adjust the CAL control to the SET mark.  Then move the switch to the REF position and read the SWR on the upper scale.

The SWR meter also indicates Percent of REFlected power.  To read this, use the lower section of the upper scale.  25% reflected power is right at a 3:1 SWR. 

Just a side note.....SWR meters are designed to work for a specific frequency range.  This meter is accurate for those frequencies used by a CB radio.  Use of the meter for other frequencies is not recommended as the accuracy is not guaranteed (or specified).

The Flex-3 adjusted very well.  On Channel 1, I was able to get 1:1.  On Channel 20, SWR as about 1.2:1 and at Channel 40, it was right at 1.4:1.  Since the off-road community here in central Arizona uses Channel 4 as their default channel, I prefer the antenna be adjusted such that I have the lowest SWR on my most frequently used channel. 
 

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