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Question by JAA: Mobile HAM radio antenna tuning (length) to optomize preformance?
I have a yasue FT 2900R radio and a Workman steel wire antenna ~53″ long (136-174 MHZ 3db gain, it says Workman V324… The radio (installed in my truck) works but reception in not ideal at farther distances. I have a friend that has a meter and knows how to tune it, but he is out of the country for a while. Can somone provide a rough length of the antenna intil he gets back so i can use the radio.. frequency i use is 151. thx
Best answer:
Answer by wires
The antenna seems to be too long for your frequency. A 1/4 wavelength at 151 MHz is about 18.6 inches. 1/2 wave is about 37.2 inches. Do you have the right coil for this antenna? That could make a big difference. Mostly, a radio will receive with almost anything. A length of wire is a length of wire and picks up the signals it sees. There are conditions where a particular length can cause poor reception but for the most part getting the length right is for transmitting. You need to match the antenna to the frequency band to prevent good transfer of power and prevent possible damage to your transmitter. Check all your connections. Poor reception is an indication that a connection may be bad. Your coax could also have a bad spot in it. Is there any place where it’s bent or get might get crushed?
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at the base of this antenna is a coil. the coil has a profound affect on the resonate length of the rod. the manufacture should have provided a cutting chart showing length versus operating frequency because it cannot be calculated by formula. larson antennas always did, i looked at the workman website and didn’t see your antenna there or any instructions. i suggest you either wait, or call the factory at 800.537.7107 for assistance.