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Setting Up My New VHF.

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My new VHF + AIS transceiver is being fitted today so by end of day I should be seeing AIS data on my plotter and gps position on my vhf. Also getting second station mic & controller installed in cockpit so I can easily listen to & use vhf from helm.

 

This was all triggered a month ago when I tried to do a routine radio check. My transmission was weak & broken from Gulf Harbour and inaudible from Kawau or Barrier.

 

Assumed problem most likely in antenna / cable / connectors so when we found a connection under the mast that was corroded we felt onto the problem. And when we cut the coax at base of mast to check condition and found it was literally dripping with water we assumed we had found the culprit so replaced the entire cable & antenna from top of mast to back of set with no connector.

 

But radio check yielded same result!

 

Which gave me flashback to a time many years ago when I foolishly pressed the PTT button on my vhf before I had connected the antenna cable. The lack of correct impedance into the back of the vhf blew the transmission output circuit. Had to buy a new unit.

 

Checking with manufacturer they confirmed same thing likely to have happened here ie if you have a poor quality antenna / cable / connector / splitter then you are risking damage to your vhf set every time you use PTT button.

 

Last weekend I asked a couple of friends out on the water when they had last done a proper long range radio check - answer never.

 

I wonder how many sub-standard vhf installations are floating around the gulf?

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The answer to that is "a lot". Maybe more than half.

 

Low quality antenna cable and crappy, poorly installed connections, no drip loops etc is very common. Absolutely you should never try to transmit with no antenna - the output power must go somewhere, and will often break the radio. Really bad antennas are virtually disconnected as well, so they can break the radio as well, as Aleana says above.

 

However in this case Changed said it worked OK without the splitter, so its likely to be a cable, connector, or splitter issue.

 

It's pretty easy to test an antenna install, using a SWR meter. I can do that for anyone around the Gulf Harbour area who would like to know...

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I  bought a Pacific aerials unit with cable & plug which screws on back of SH vhf.

Is that not sufficient?

https://www.burnsco.co.nz/shop/rv/electronics/antennas-other-electronic-accessories/pacific-vhf-mast-aerial-seamaster-p6001

+ 100$ cable

Drip loop?

 

Reception is not has good as my 50yo phillips.

Haven't done a radio check yet, will get the mmsi first.

 

Squirreling it up the mast took two years of procrastination after the debacle with the wind sensor.

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Yes our SWR test predictably showed old antenna & cable as terrible but new setup as great.

 

But to add to the confusion the SWR showed the vhf transmission to also be fine - hence our confusion about poor radio test result.

 

Our verdict was that vhf set was transmitting some kind of carrier signal (as seen by SWR) but the voice part was not making it onto carrier signal correctly. This is the bit that I think was broken by me using PTT with a deteriorated antenna & cable.

 

A proper radio check needs to be done at real distance eg in Auckland that means the outer gulf or Barrier - not from Waiheke!

 

I once had to issue a pan-pan from mid English Channel 30nm from land and nobody could hear me. I’d be talking happily to Solent CG and marinas at 2-3nm range for years so assumed all was well. But after my Channel scare I had the set tested and found a combination of factors had caused a 50% signal attenuation meaning I couldn’t be heard when I needed it most.

 

Like you IT, based on NZ’s older fleet of vessels, I suspect the majority of boaties are sitting on dangerously poor quality vhf setups without realising it.

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SWR does not confirm transmission. It checks the Standing Wave Ratio - The standing wave ratio is exactly what its name depicts. It's a ratio based on how much power can be delivered to your antenna VS the amount of power that is reflected by your antenna back down the coax to your radio.

It does NOT and cannot, check that the radio is actually transmitting anything useful. It DOES test the coax and antenna. You need a decent , functioning radio as well, as Aleana found out.

Any decent tech should be able to check this for you. If they don't seem to know about it, move on.

Just in case some of you haven't realized it, marine electronics is my job.

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I just called CC on 16 announcing test call. They then direct you to a new frequency. Remember LP in the marina. Previous VHF worked all the way around the north island bar the Tasman once we got out a bit.

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