check ebay for the low pass filter.
drake and bencher both make very good ones.
just buy one that is advertised in the ham market and stay far away from any that are advertised in the CB market and you will be fine.
i would not buy a new one as they are very expensive, and there are always good deals to be had used because so many people buy one thinking that it will solve their problems only to find out that harmonics were not the cause of the interference to the neighbors.
OK, this is from experience:
DONT TELL YOUR NEIGHBORS THAT YOU MIGHT BE INTERFERING WITH THEIR STUFF!!!!!
the reason for this, is that most people have absolutely no clue about RF, radios, CB, interference, or electronics in general.
if you tell them that you might interfere with their TV or phone; every time their cable goes out or the phone makes a funny noise, they will be at your door blaming you.
and even when you KNOW 100% for sure that you weren't even on the radio, they will still think it was you, and will continue to think it forever.
now, if you happen to be friends with your neighbors, then there is a slight chance that they might not blame you.
yes, this is just my opinion, so hopefully others will chime in and say whether their experience has been similar to mine or not.
a question i have for you is, is the law on your side?
by that i mean, do you live in an HOA or other antenna restricting neighborhood?
if so, then you are screwed and are at the mercy of your neighbors.
if not, then you just need to make sure that DTB tunes your radio within legal specs.
make sure he sets your deadkey at about 3.5 watts, and that he sets the modulation so it wont exceed 100%
also, have him tune the 54mhz coil in the radio with his spec analyzer to make sure you arent putting out any harmonics.
if you do this, you really dont need a low pass filter, and if you do interfere with anyone's electronics; you can be sure its because of the cheap way they were manufactured and has nothing to do with your station.
you are in the enviable position of being part of the 1% of cb'ers that operate a completely legal station. LOL
if you interfere with their cable TV, tell them to call the cable company.
if you interfere with their phone, tell them to call the phone company.
if the power lines near your house interfere with your radio, call the power company and tell them to fix the problem.
if you are worried about your antenna being seen, let me know and i will tell you how to make an invisible antenna.
as long as you dont tell anyone that you have a CB setup, no one will bother you.
good luck,
LC