craigh Posted September 23, 2014 Share Posted September 23, 2014 Is there a limit on the length of cable between the FM transmitter and the antenna?In the past I have had the antenna (dipole antenna) in the garage, using a cable about 20 feet long, and have not had any issues. This year I thought about moving the antenna out into the yard, but I want to know if there is a limit on how long of a cable I can run between the transmitter and the antenna. The reason for moving the antenna is to improve reception. Craig Link to comment Share on other sites More sharing options...
Archer Posted September 24, 2014 Share Posted September 24, 2014 (edited) My cable length is about 30ft with a connector in the middle. I have a 5 watt transmitter and can be heard 5 miles away clear as a bell on some night. BTW...if you go to kevinkolak.com you can get a feel for the size of the display but my transmitting antenna is on my chimney that you can't see in any of the videos. The videos were shot from 1/4 mile away as I stood on a hill in a farmers field. Edited September 24, 2014 by Archer Link to comment Share on other sites More sharing options...
crackchecker Posted September 24, 2014 Share Posted September 24, 2014 Legally? FCC has a rule on this.... Of course, as long as your not beatting the crud out of everyone for miles with your transmission usually people won't care. (story): Seems everyone has taken up using the same frequency as I in my town for their shows too (7 of us now). (not a problem, actually its handy. now the visitors don't have to think about what to tune their radios to) However, we have ONE guy who has had no reguard for anyone else and purchased a High power transmitter and now steps on everyone else for a mile and half radious of him... When we asked him nicely to tune it down, he just smiled and blew us off. This year...If he plans to proceed business as usual, he might find some interferance... Link to comment Share on other sites More sharing options...
craigh Posted September 24, 2014 Author Share Posted September 24, 2014 I am using a half watt transmitter (Ramsey FM30B) with a Tru-Match Dipole antenna, connected with a 25 foot cable (RG58). I have been using this setup for many years now.I was thinking that moving the antenna out into the yard would help improve the signal just a bit. I am not looking to violate FCC rules, just trying to get my broadcast cleaned up a bit.A friend of mine had hooked up his transmitter and antenna with a 100' cable and found the signal was really bad. Thus the question about cable length.Maybe the question should be expanded to - what is the best type of cable to use and what is the maximum length that can be used? Craig Link to comment Share on other sites More sharing options...
craigh Posted September 25, 2014 Author Share Posted September 25, 2014 Sort of found an answer - using a .5 watt transmitter the cable should be short and the antenna should be as high as possible. Not an exact answer, but I think I can safely rule out a 100' cable.I might just stick with what I have been using or I might try hanging the antenna in the attic and use a 30' cable. Craig Link to comment Share on other sites More sharing options...
Max-Paul Posted September 26, 2014 Share Posted September 26, 2014 Legally? FCC has a rule on this.... Of course, as long as your not beatting the crud out of everyone for miles with your transmission usually people won't care. (story): Seems everyone has taken up using the same frequency as I in my town for their shows too (7 of us now). (not a problem, actually its handy. now the visitors don't have to think about what to tune their radios to) However, we have ONE guy who has had no reguard for anyone else and purchased a High power transmitter and now steps on everyone else for a mile and half radious of him... When we asked him nicely to tune it down, he just smiled and blew us off. This year...If he plans to proceed business as usual, he might find some interferance... There is an old saying that fairly well says it all. Drop a dime on him, call the FCC. Then sit back and smile...But have your ducks in a line and dont flaunt the rules yourself. Link to comment Share on other sites More sharing options...
crackchecker Posted September 29, 2014 Share Posted September 29, 2014 There is an old saying that fairly well says it all. Drop a dime on him, call the FCC. Then sit back and smile...But have your ducks in a line and dont flaunt the rules yourself. I understand... I plan to have ANOTHER talk with him about turning it down a little this year. I'm just outside of his range so he doesn't hit me at all. Two others are NOT so lucky though...I feel for them. We've all talked about swithing all of our freqencies (except him) just to avoid any further conflict. Link to comment Share on other sites More sharing options...
Max-Paul Posted October 1, 2014 Share Posted October 1, 2014 Ok techical answer to the question about cable and length. All cables have a db loss. Every 3db loss halves your signal. At the same time, every 3db gain of an antenna doubles the effective power of the transmitter. Example, you have a .5 Watt transmitter with a cable that has a 3db loss for the given length. At the antenna then you would only have .25 watts available. But then the antenna has a 6db gain. Effectively you would be like you where transmitting 1.0 Watts. This is cause the .25 would be doubled twice. So .25 doubled once is .5 and again would be 1 watt. Ok RG-58 is not as good as RG-8. And a higher frequency has more loss than a higher frequency Do a google search on RG cable and Attenuation charts for a given RG cable. BTW RG=913 is even better, but RG-58 will do for your purpose, unless using over 50 feet. DE KF0OX Link to comment Share on other sites More sharing options...
Recommended Posts