Welcome Visitor! Please take a few seconds and 
Southern3.0
Well-Known Member
OK, i promised to do this, so I'll put it in it's own thread and add it to the FAQ:
What you need to tune an antenna:
SWR meter -Even the radio shack model will work alright, though it's not
perfect.
Radio - need one that works...
Short coax jumper -to connect the radio to the transmitter port of the SWR meter.
knowledge of how to adjust your particular antenna
-some have a large screw in the top to adjust the length of the antenna, some need to be cut, others have sleeves that slide up and down the antenna, and others have set screws that loosen so you can move a metal "Stinger" up and down to adjust the length of the antenna.
here's a short technical blurb about what I'm talking about before i get into the instructions
Tuning your antenna consists of adjusting the length of the antenna to correspond with a particular frequency. the lower the frequency (and thus the channel, in the case of CB), the longer the antenna needs to be. this can be calculated (in feet) by (234/(frequency in Megahertz)). this generally gives the length the wire in your antenna, even if it's wound around a fiberglass stick and is physically shorter.
what to do:
connect the coax jumper from the radio to the transmitter side of the SWR meter (or TX)
connect the antenna to the antenna port on the SWR meter
you should now have:
[Radio]---[Meter]----[Antenna]
most inexpensive SWR meters have a "cal" knob on them. these instructions are written for those types of meters.
these meters generally have a "cal/ref" or "cal/fwd/ref" modes. "cal" is calibration, "ref" is reflected, and "fwd" is forward power.
set your radio to the middle channel (20 for a 40 channel Channel radio, 13 for a 23 channel radio)
put the meter in "cal" mode, there should be a cal mark on the meter face. Key the transmitter, and adjust the cal knob until the meter needle is set at the cal mark, or maximum meter reading (NOT pegged, just the highest meter reading), then unkey the transmitter.
set the meter to "ref" mode.
key the radio, and see where the needle goes. make a note of this. most SWR meters have a SWR scale on the meter face that reads 1 2 3 ... . if the needle barely moves when you key up the radio, your SWR is relatively low, and you are in good shape.
switch to channel 1, and key the radio. make a note of how much power is reflected, and repeat with channel 40 (or 23, in the case of 23 channel radios)
if your reflected power is low across all channels, you are doing well. Ideally, your antenna will have the least amount of power reflected on the "middle" channel, and will be SLIGHTLY higher on the "bottom" and "top" channels..
if, however, you have a high SWR (the ref reading is high on any of the above readings), you need to tune your antenna.
if channel 1 has a lower reflected power than on channel 40, your antenna needs to be shortened. it is generally better to take your time and shorten your antenna in SMALL increments, especially with the types of fiberglass whips that require cutting the antenna wire, since it is a LOT easier to SHORTEN the antenna in this case than to lengthen it.
if channel 40 has a lower reflected power than channel 1, your antenna is too short, and needs to be lengthened. with the types of antennas with set screws, sleeves, and top screws, this is easy to do. with the types of antennas that need to be cut, you CAN lengthen them by adding a quick disconnect or a spring to the base of the antenna, OR by possibly moving some of the wire up the fiberglass rod, if the antenna is CLOSE to being the correct length.
the main idea here is to MINIMIZE your REFLECTED power, so you want the "ref" setting on your meter to be at a minimum.
if you're tuning co-phased (dual) antennas, you tune BOTH antennas the SAME amount. other than that, it doesn't change. if you shorten one, shorten the other, etc.
also, when tuning antennas, do it with the doors closed, and away from buildings and such (pull to the end of your driveway, don't do it in your garage) I tune antennas out in front of my house when i do it... or, if I'm REALLY bored, I'll go out tot he back of the grocery store parking lot... lots of empty space The main idea is that you want the vehicle to be as it would be while driving, and opening the doors affects the ground plane.
if all else fails, don't hesitate to ask someone who knows what they're doing for help! Ham radio operators and professional radio installers can be very helpful (but the pros usually like to get paid for what they're doing, thus PROFESSIONAL), as can other CB'ers.
----from the Firestik Website--------
hope you don't mind but I found something at Firestik's website I thought might compliment your stickied post. If not, feel free to edit or delete it.
HIGH SWR TROUBLESHOOTING
For Standard Firestik Antenna Installations (not applicable to no-ground-plane installations)
Compliments of Firestik® Antenna Company Technical Support Team
Copyright © 1996 Firestik® Antenna Company
The following list shows the most probable causes of high SWR in order from the most common causes to the least common causes. If experiencing SWR problems, check each of the following conditions in the order shown until problem has been uncovered.
Shorted Stud Mount
Disconnect coaxial cable at antenna mount. Test continuity from mount to antenna coupling nut. There should NOT be any continuity. If shorted, reposition or replace insulators and retest.
Improper Type and Length of Coax
Single antenna installations require RG-58 type coax and dual antennas require the use of RG-59 type coax cables. We recommend 18 foot long coax leads from the radio to each antenna, especially on installations that are displaying high SWR problems.
Shorted Coaxial Cable
Disconnect coax at radio end. Test for continuity between center pin and threaded sleeve. There should NOT be any continuity. If shorted, repair and retest.
No Chassis Ground at Antenna Mount
Test for continuity between the antenna mount and the vehicle's common ground. There MUST be continuity. Repair and retest as required.
Open Coaxial Cable Center Lead
Disconnect coax at radio end. Test for continuity from center pin to antenna base. There MUST be continuity. If necessary, repair and retest.
Open Coaxial Cable Ground Shield
Disconnect coax at radio end. Test for continuity from the antenna mount to the coax connectors threaded sleeve at the radio end of the coax. There MUST be continuity. If necessary, repair and retest.
Improper Installation Location
Transmit antennas need free space around them if expected to perform properly. If more than 30% of the antennas overall length is parallel to the side of the vehicle and within twelve inches of that surface, SWR problems are probable, i.e. between truck cab and shell, corner of truck bed near cab, low mount position on motor-home, etc. Relocate the antenna to a position of performance (versus convenience or appearance) and retest.
Insufficient Ground Plane Available
Fiberglass, plastic and thin aluminum vehicle bodies lack the reflective characteristics needed for proper antenna performance. On some occasions, running a 12ga or heavier wire from the antenna mount to the vehicles chassis ground will be sufficient. Otherwise, a no-ground-plane antenna system may be required.
Low Quality Coax Cable
Delivering radio frequency to an antenna via poor quality coaxial cable is the equivalent of watering your lawn with a hose full of holes. The bitterness of low quality will linger long after the sweetness of low price is gone. Use high quality coax only.
Antenna Tuned Without Tip
If the antenna is tuned without the tip then put on after tuning is completed, the SWR will change when the tip is installed. All readings must be made with the antenna tip in place.
Defective SWR Meter
Some are made bad and others have been known to go bad. Try to confirm readings with a second meter.
Damaged Antenna
Aside from apparent damage that is visible from the antenna striking immovable solid objects, you can test for any internal damage by checking continuity from the antenna base to the tunable tip extender or end of wire. There MUST be continuity. If there is no continuity, the antenna must be repaired or replaced.
What you need to tune an antenna:
SWR meter -Even the radio shack model will work alright, though it's not
perfect.
Radio - need one that works...
Short coax jumper -to connect the radio to the transmitter port of the SWR meter.
knowledge of how to adjust your particular antenna
-some have a large screw in the top to adjust the length of the antenna, some need to be cut, others have sleeves that slide up and down the antenna, and others have set screws that loosen so you can move a metal "Stinger" up and down to adjust the length of the antenna.
here's a short technical blurb about what I'm talking about before i get into the instructions
Tuning your antenna consists of adjusting the length of the antenna to correspond with a particular frequency. the lower the frequency (and thus the channel, in the case of CB), the longer the antenna needs to be. this can be calculated (in feet) by (234/(frequency in Megahertz)). this generally gives the length the wire in your antenna, even if it's wound around a fiberglass stick and is physically shorter.
what to do:
connect the coax jumper from the radio to the transmitter side of the SWR meter (or TX)
connect the antenna to the antenna port on the SWR meter
you should now have:
[Radio]---[Meter]----[Antenna]
most inexpensive SWR meters have a "cal" knob on them. these instructions are written for those types of meters.
these meters generally have a "cal/ref" or "cal/fwd/ref" modes. "cal" is calibration, "ref" is reflected, and "fwd" is forward power.
set your radio to the middle channel (20 for a 40 channel Channel radio, 13 for a 23 channel radio)
put the meter in "cal" mode, there should be a cal mark on the meter face. Key the transmitter, and adjust the cal knob until the meter needle is set at the cal mark, or maximum meter reading (NOT pegged, just the highest meter reading), then unkey the transmitter.
set the meter to "ref" mode.
key the radio, and see where the needle goes. make a note of this. most SWR meters have a SWR scale on the meter face that reads 1 2 3 ... . if the needle barely moves when you key up the radio, your SWR is relatively low, and you are in good shape.
switch to channel 1, and key the radio. make a note of how much power is reflected, and repeat with channel 40 (or 23, in the case of 23 channel radios)
if your reflected power is low across all channels, you are doing well. Ideally, your antenna will have the least amount of power reflected on the "middle" channel, and will be SLIGHTLY higher on the "bottom" and "top" channels..
if, however, you have a high SWR (the ref reading is high on any of the above readings), you need to tune your antenna.
if channel 1 has a lower reflected power than on channel 40, your antenna needs to be shortened. it is generally better to take your time and shorten your antenna in SMALL increments, especially with the types of fiberglass whips that require cutting the antenna wire, since it is a LOT easier to SHORTEN the antenna in this case than to lengthen it.
if channel 40 has a lower reflected power than channel 1, your antenna is too short, and needs to be lengthened. with the types of antennas with set screws, sleeves, and top screws, this is easy to do. with the types of antennas that need to be cut, you CAN lengthen them by adding a quick disconnect or a spring to the base of the antenna, OR by possibly moving some of the wire up the fiberglass rod, if the antenna is CLOSE to being the correct length.
the main idea here is to MINIMIZE your REFLECTED power, so you want the "ref" setting on your meter to be at a minimum.
if you're tuning co-phased (dual) antennas, you tune BOTH antennas the SAME amount. other than that, it doesn't change. if you shorten one, shorten the other, etc.
also, when tuning antennas, do it with the doors closed, and away from buildings and such (pull to the end of your driveway, don't do it in your garage) I tune antennas out in front of my house when i do it... or, if I'm REALLY bored, I'll go out tot he back of the grocery store parking lot... lots of empty space The main idea is that you want the vehicle to be as it would be while driving, and opening the doors affects the ground plane.
if all else fails, don't hesitate to ask someone who knows what they're doing for help! Ham radio operators and professional radio installers can be very helpful (but the pros usually like to get paid for what they're doing, thus PROFESSIONAL), as can other CB'ers.
----from the Firestik Website--------
hope you don't mind but I found something at Firestik's website I thought might compliment your stickied post. If not, feel free to edit or delete it.
HIGH SWR TROUBLESHOOTING
For Standard Firestik Antenna Installations (not applicable to no-ground-plane installations)
Compliments of Firestik® Antenna Company Technical Support Team
Copyright © 1996 Firestik® Antenna Company
The following list shows the most probable causes of high SWR in order from the most common causes to the least common causes. If experiencing SWR problems, check each of the following conditions in the order shown until problem has been uncovered.
Shorted Stud Mount
Disconnect coaxial cable at antenna mount. Test continuity from mount to antenna coupling nut. There should NOT be any continuity. If shorted, reposition or replace insulators and retest.
Improper Type and Length of Coax
Single antenna installations require RG-58 type coax and dual antennas require the use of RG-59 type coax cables. We recommend 18 foot long coax leads from the radio to each antenna, especially on installations that are displaying high SWR problems.
Shorted Coaxial Cable
Disconnect coax at radio end. Test for continuity between center pin and threaded sleeve. There should NOT be any continuity. If shorted, repair and retest.
No Chassis Ground at Antenna Mount
Test for continuity between the antenna mount and the vehicle's common ground. There MUST be continuity. Repair and retest as required.
Open Coaxial Cable Center Lead
Disconnect coax at radio end. Test for continuity from center pin to antenna base. There MUST be continuity. If necessary, repair and retest.
Open Coaxial Cable Ground Shield
Disconnect coax at radio end. Test for continuity from the antenna mount to the coax connectors threaded sleeve at the radio end of the coax. There MUST be continuity. If necessary, repair and retest.
Improper Installation Location
Transmit antennas need free space around them if expected to perform properly. If more than 30% of the antennas overall length is parallel to the side of the vehicle and within twelve inches of that surface, SWR problems are probable, i.e. between truck cab and shell, corner of truck bed near cab, low mount position on motor-home, etc. Relocate the antenna to a position of performance (versus convenience or appearance) and retest.
Insufficient Ground Plane Available
Fiberglass, plastic and thin aluminum vehicle bodies lack the reflective characteristics needed for proper antenna performance. On some occasions, running a 12ga or heavier wire from the antenna mount to the vehicles chassis ground will be sufficient. Otherwise, a no-ground-plane antenna system may be required.
Low Quality Coax Cable
Delivering radio frequency to an antenna via poor quality coaxial cable is the equivalent of watering your lawn with a hose full of holes. The bitterness of low quality will linger long after the sweetness of low price is gone. Use high quality coax only.
Antenna Tuned Without Tip
If the antenna is tuned without the tip then put on after tuning is completed, the SWR will change when the tip is installed. All readings must be made with the antenna tip in place.
Defective SWR Meter
Some are made bad and others have been known to go bad. Try to confirm readings with a second meter.
Damaged Antenna
Aside from apparent damage that is visible from the antenna striking immovable solid objects, you can test for any internal damage by checking continuity from the antenna base to the tunable tip extender or end of wire. There MUST be continuity. If there is no continuity, the antenna must be repaired or replaced.
