VHF Antenna Questions

[jarway]

I have an old VHF antenna that came off a boat I am restoring and would like to use it for a new ICOM VHF radio I am purchasing. Is there a way to test the functionality of the antenna? Any impedence tests I can do? The fiberglass surface is weathered and I was going to put a coat of epoxy paint to seal but don't want to mess with it if the antenna isn't any good. Would like to keep it since it fits the mount on the center console and can't seem to find another kind that uses this mount. I also like to re-use stuff instead of purchasing new if possible.<br /><br />I also saw some other posts about using a splitter for both a VHF radio and a AM/FM radio off of a VHF antenna. Does this work?<br /><br />Any advice would appreciated.<br /><br />Thanks in advance.

 

[Boatist]

Re: VHF Antenna Questions

Hook up a SWR meter and put radio on 1 watt, switch to a unused channel not 16 and check the SWR. If it is under 1.5 to one and it should be then check one more time while flexing the antenna like would happen when running in rough water. If still under 1.5 to 1 it is good to go.

 

[jarway]

Re: VHF Antenna Questions

Thanks Boatist. Will try the check.

 

[jarway]

Re: VHF Antenna Questions

After discovering that SWR means Standing Wave Ratio Meter and the fact that I don't have one and don't know where I'd borrow one, is there another test option? The following link explains the test that Boatist was talking about. May be helpful for other novices like me: http://www.firestik.com/Tech_Docs/Setting_SWR.htm <br /><br />Also what about splitting the signal from the VHF antenna for the other radio?<br /><br />Thanks again.

 

[chuckz]

Re: VHF Antenna Questions

Splitting the signal is a compromise. The antenna is tuned for the VHF band not the FM band. You will get better reception than without an antenna, but not as good as with a dedicated FM antenna.<br /><br />Find a good radio shop or a Ham operator. They should be able to check the antenna for you.

 

[jurgenscraft]

Re: VHF Antenna Questions

Good morning, maybe it will be worth your while to buy a new VHF antenna for your new Radio, that is what I would do. Once you have surface corrosion on the surface of the antenna ( fibre glass )then I believe the antenna has seen the end of it's usefull life,I would not risk it especially if you go out to sea,<br />"DO NOT SPOIL THE SHIP FOR A Ha PENNIES WORTH OF TAR" the old saying goes. or what we say here in South africa " GOEDKOOP IS DEURKOOP" buying cheap can be expensive,<br />Regards.<br />William Wright

 

[Boatist]

Re: VHF Antenna Questions

If you decide to get a new antenna You should know a big difference in antennas. I Reccommend a Shakespeare Galaxy 5225 or better. The 5225 will hold up for many years and is a great antenna. Even with a new antenna installed You should check your Standing Wave Ratio. This will tell you that your coax and it connector is not shorted or open and verify that Antenna and Radio is good.<br /> <br />Just go to the mega mall here and search for "Antenna Tester"<br /><br />Sold here for $46<br /><br />Lots of people have a SWR Bridge. One for the Marine band or Ham radio 2 meter band will work fine. Most CB model will not but have seen a few that due. When I go camping to the ocean I take mine with me and every year check an antenna or two for people I have meet having radio problems.

 

[jarway]

Re: VHF Antenna Questions

Thanks everyone for the helpful tips. I understand the the American version of the saying and it is good to know the South African just in case. Will probably heed your collective advice and start shopping for a new antenna.