# Do VHF antennas go bad?



## follysurf (Mar 31, 2011)

Hi all, 

This may be a stupid question, but I am about to pull new coax in the mast while it is down and am wondering if I should replace the antenna as well to avoid a problem later on. The current coax has deteriorated and been repaired several times. When everything was connected the VHF worked so the antenna is good although it does have mild corrosion. 

Should I assume that everything will work well and not waste my money on a new antenna?

Thank you.


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## btrayfors (Aug 25, 2006)

Maybe, but it would be better to replace the antenna while the mast is down. If you're seeing corrosion on the antenna, particularly if it's a coil-type like a Metz, then replace it. VHF antennas are very cheap insurance and, after all, the VHF is arguably the most important safety thing on the boat.

Coax repaired? Why? It should never be necessary to "repair" coax, unless it's been improperly installed.

If you can, use RG-213, 214, or LMR-400 coax for the transmission line, especially if the run is 50' or more. Alternatively, if you can't fit the larger coax then use RG-8X and install it so it's protected and you won't ever have to repair it.

Bill


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## olson34 (Oct 13, 2000)

*Replace It*

I replaced a 15 year old Metz-type antenna and the run of coax to it. The antenna came off in pieces and I knew from research that the old coax had been superseded in the market by better product.
In the whole scheme of things (a re-rig) it was cheap. We pulled new tinned wired thru and replaced the UV-damaged anchor, steaming and foredeck lights, too.

Far easier (and a lot less labor intensive - i.e. costly) to do this work all at once, with the spar horizontal.

Mind you, all this stuff worked to some extent before the replacement/upgrade.
It has a useful-life-span, like all the systems parts on a boat.


You may be pleasantly surprised at the increase in range when you then make and receive calls on your VHF.

Sidebar: You did not ask, but since it's winter and unsolicited advice is free on the internet, take your VHF radio in for a free check up in the off season... I would imagine that most reputable marine electronics shops will do a no-cost bench check for you.......
We have an excellent shop here that's been doing this for decades. They keep handing back my '88 Furuno radio and telling me to keep on using it - no freq. drift and up to rated power output).

(I asked if they were ever tempted to say it was "showing a diminished thermothrockle output" and then sell me a new one. They laugh and say they do not do business that way!  )

One of these days I will probably get a new fancy DSC radio, but for now, it's a "feature" that I do not need.

Best,

LB in PDX


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## MarkSF (Feb 21, 2011)

Definitely worth replacing it. Here's the one I just used :

Shakespeare Antenna Specifications: Shakespeare Squatty Body® 5215-AIS VHF Marine Band

About $60 online.

I spent a lot of time tracking down an interference / bad reception problem. In the end the fix was to replace the RG8X cable between the radio and the base of the mast. (there's a union at the mast base and the thick stuff goes up the mast). So if you're replacing the mast cable and the antenna, I'd go the whole way and fit new cable all the way to the radio, all with quality gold-plated solderable Shakespeare connectors. I trust the Shakespeare RG8X too.


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## smurphny (Feb 20, 2009)

Have had a lot of these on both power and sail and have never had one go bad except for plastic mount-type. Actually use an older one on mast because it's obviously made a lot better than the new one I keep for a spare.


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## follysurf (Mar 31, 2011)

Thanks for the responses. My original thought was to go ahead and replace so I will stick with that plan. I agree that it is an inexpensive piece in the grand scheme of things. I am also pulling tinned electrical wire and replacing the anchor, steeming and foredeck light. I would rather do everything right and know that all is good when I step the mast. 

As for the repaired coax... the connections between the mast base and deck entry had been repaired several times. My guess is that the wire got kicked around a bit by the previous owner.

I was planning on using RG-8X but will look into the others you mentioned.


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## neverknow (Feb 2, 2011)

I was a communication electronic tech in the navy yrs ago. Keeping the radios on the ship going was my job.

The antennas do not actually ever "go bad" however just like everything they are susceptible to water damage. If yours is sealed and has no signs of corrosion it will be fine. 

All that is inside of them is a wire of the proper wave length, keep it dry and it will last forever.


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## ccriders (Jul 8, 2006)

One last thing,
It is very important that the coax is attached to the masthead inside the mast with a hanger, that there is an "O" ring seal where the coax leaves the mast, that there is a drip loop in the coax before it attaches to the antenna base and that the attaching connector is weather proofed. I use shrink wrap for the weather proofing but left the bottom end of the shrink wrap "unshrunk" so as not to trap moisture in the connector but protect it from rain, spray and condensation.
With anything electronic, you will have more problems with mechanical parts than electronic. Hence the care taken in installation will pay dividends.
John


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## follysurf (Mar 31, 2011)

Olson34: From looking at the current VHF, I'm pretty sure it is original to the boat, 1972! It worked prior to the coax seperating so I am planning on continuing to use it although I know even the cheap ones are probably better. I am thinking of upgrading but it is not as pressing as other repairs ( I am running new coax from the deck entry to the radio). Maybe I will have it tested just for fun.


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## MarkSF (Feb 21, 2011)

Do a radio check when it's all done, reception and transmission.

I don't think analogue electronics have changed that much since 1972. It's the extra digital features that have moved on.

If you do ever upgrade I just installed the Standard Horizon GX2150 with DSC and AIS. It has a really good 80db receiver too. Quite impressed.


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## olson34 (Oct 13, 2000)

follysurf said:


> Olson34: From looking at the current VHF, I'm pretty sure it is original to the boat, 1972! It worked prior to the coax seperating so I am planning on continuing to use it although I know even the cheap ones are probably better. I am thinking of upgrading but it is not as pressing as other repairs ( I am running new coax from the deck entry to the radio). Maybe I will have it tested just for fun.


Wow. I wonder if it's old enough to be a crystal radio? Additionally, does it have all of the nowadays standard channels you see listed for the new radios?
Given the age, and the low prices for new radios, I would be tempted to replace it. Of course if it works you could wait... it's not like you would have to climb the mast to replace it! 

Ours has the full range of regular channels and a bunch of weather channels as well, so it's still just "modern enough."


Regards,
L


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## gus_452000 (Mar 11, 2012)

I have been an amateur radio "nut" for years and just getting back in to sailing now with my children, but and I find this a little disturbing, that I have been on a few boats that have asked if I would take a look at there radio as it dosen't work as well as it did.

It would be advisable to change coax every 5 years at the very most, more so at sea, coax has the ability to wick moisture to its insides, almost like capillary acation. One boat I went on hadnt had his coax changed since he bought the boat 12 years before and the coax was as good as wet string, it was also we later discovered why he had a leak in the boat! The coax was so full of water that it was slowly dripping from the back of the PL259 at the back of his radio, and although he had used massive amounts of sealent around were the coax entered the cabin, thinking it was leaking there in actual truth the water was coming in from the inside of the coax.

Now VHF or SSB radios maybe the one life line we have left when all goes wrong, if its not working because the coax is old and full of water, what price a life?

Not having a go at anyone here, but what I have seen many people think coax is good for 30 years, its not and at sea, its lifespan has been reduced even more, no matter how well made the leads are and who made them, water, condensation will get in. Always better to check them, and relace when you need to not after they fail.

Just my 2 cents worth.


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## stevensuf (Feb 26, 2012)

+1 for the standard horizon , great unit!


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## Capt Len (Oct 9, 2011)

Once a year the DOT checks all my radios for output, frequency ,reflective signal as well as wiring, battery condition ,manuals ,fuses. DSC and looks at my radio log for daily record of calls. If this was for the safety of my family I could see the value but just because I carry passengers ???


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## dacap06 (Feb 2, 2008)

It's a little late to answer for the original poster but maybe someone else can use this info.

Yes, the simplistic way to say it is that antennae do "go bad" as they age, and so does coax exposed to the elements if it is foam-filled. Antenna characteristics change as they deteriorate. Dielectric material deteriorates, metal corrodes, and so on. It all causes signal attentuation. As the antenna changes, it can also cause impedance mismatches, which causes reflectance. That is probably more than you need to know. Pragmatically, the question should be how do you know when to replace it?

The way to tell whether to replace your setup is to measure the Standing wave ratio of the signal. That can be done by putting an SWR meter between the radio and the antenna and then measuring during transmission. Ideally, the SWR should be 1.0. That ratio means that all the RF energy the radio is putting out ends up as electromagnetic energy in the air. An SWR ratio of 1.5 means 2/3 of your energy ends up in the air and the other third is absorbed by attenuation or is reflected back into the radio and turned into heat in the final stage of the RF amplifier, so this setup would have to put out half again as much power as an ideal setup to get the same amount of power into the air. Heat is the great enemy of semiconductors, so you might guess that reflected energy is not at all good for your unit.

Measuring SWR is simple, but you might want to find someone who is a ham radio operator and trade them a case of beer for their help on this one. They are quite likely to have an SWR meter already so you may not even have to buy one.

You can learn more about the SWR concept at 



.


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## hellosailor (Apr 11, 2006)

If the antenna was properly made and properly sealed, hermetically, it will never go bad. Of course water and heat and UV are persistent, they break down mountains so how long does an antenna stand a chance?

The coax is a bigger problem because even if it is sealed, even if the insulator is solid and can't absorb water, the cable cannot support its own weight and "proper" installation uses tie-offs to something else to support it. Tie it too tightly and you eventually compress the insulation. Don't tie it, and the pull of gravity strecthes the cable and compresses the insulation. So the coax IS going to degrade, odds are before a well-made antenna does.

An SWR meter will tell the best story, but without one, with a typical coax installation, you can figure maybe 5 years for the coax to start degrading, and then "while you're up there" a new antenna can be good preventive maintenance.


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