RE: Newbie Questions
The antenna you are using is too long for a CB, and subtracting a section makes it too short. With 3 sections, it is good at 22MHz, and as we know CB is 27MHz. You will get a high SWR which will cause heating of the final RF power amplifier stage in the CB radio. All is not lost however.
I assume the AB-15 has a "regular" (SO-239) CB-type connector on it as most do. Some have a removable plug on them, that is a terminal you can attach a wire to. This unscrews. Maybe it is already missing from yours.
This simplifies matters. The AB-15 should have also a metal ring with it that goes between the ceramic halves and has a metal strap attached to a hose clamp. The general idea here is to screw your coaxial cable's plug onto the bottom of the AB-15, then clamp the hose clamp around that, and attach the short ground wire or the grounding ring to the vehicle's metal chassis or body. This is very important. So, the hot terminal of the cable will go to the actual whip, and the ground/shield of the cable will go by the shortest possible length of strap or braid to the vehicle metallic body. CB RF does not go through paint well, be sure to have a good ground connection.
The other end of the cable you can do a variety of things with. An SWR meter will help you judge each method. The SWR meter, to be anywhere near accurate for this, has to be right at the CB, no more than 1-2FT of cable between the radio and the meter. A cheap meter is fine. From worst to best:
Just connect it to the CB and limit your transmissions to 20% duty cycle and 30 seconds max. talk time per cycle (talk 30 seconds listen 150 seconds) to avoid overheating the CB. This is the least desirable but it will work.
Use a convenient length cable and clamp a 8-12 of those clamp-on RFI ferrite blocks on it. Most electronic stores have them for about $1 or so. This does the same thing basically as the two cable coil suggestions below. The blocks can be placed preferrably near the antenna end of the cable. The extra energy trying to come back down the cable will be dissipated as a very small amount of heat in the ferrite blocks.
Use a cable that is 6-10FT longer than necessary. Take the extra length and coil it up into a 6-8" diameter circle and secure it to this shape with a few wire ties. This creates an RF choke on the outside of the RF cable and reduces the amount of RF flowing back into the CB, mostly converting it to heat in the cable. You will not detect this since you are only burning up 1-2 watts. The coil of wire can be placed preferrably near the antenna end of the cable. The coil of cable should be kept 3" from metal.
Use a cable that is 6-10FT longer than necessary. Take the extra length and coil it up into a 3-4" diameter single layer solenoid (coil) on a piece of PVC pipe and secure it to this shape with a few wire ties. This creates an RF choke on the outside of the RF cable and reduces the amount of RF flowing back into the CB, mostly converting it to heat in the cable. You will not detect this since you are only burning up 1-2 watts. The coil of wire can be placed preferrably near the antenna end of the cable. The coil of cable should be kept 3" from metal.
Use a cable of a convenient length and buy a "CB antenna tuner". The tuner goes preferrably at the antenna end of the setup, no more than 1-2 FT from the antenna. Using the SWR meter, tune it on CH 19 since that is the center of the band, for lowest SWR. The tuner usually has two knobs, and they affect each other. Go back and forth between them till the lowest SWR is obtained. The tuner must be protected from weather. This is the best solution.
Any of these solutions can be placed at the CB radio alternately, but the cable from there to the antenna will radiate unwanted RF energy and cause inefficiencies, not only with transmit, but with receive. Matching or supression should always be done at the antenna. SWR measurement should be done at the CB.
Hope this helps.
Looking at it now I clearly see where it splits. Can't believe that tripped me up as long as it did. Well my mounting woes are solved, thanks.
