VHF Antenna Cable Length?

[Chrusty 1]

Sorry if this is a bit of a numpty question, but for me it has just never cropped up before. Can anybody tell me if it's ok to shorten the cable between the antenna and the transceiver? My boat has never had a fixed VHF before, and I have to fit a new antenna. There does seem to be a lot of cable with it that I don't need...........or do I?

Somebody at one time told me that the cable length was cut to match the wave length of the antenna. So I am wondering will I do any harm by shortening it?

Thanking you in anticipation.

 

[ProDave]

It shouldn't matter.

If the aerial is correctly tuned and matched then the cable length will not alter anything, so go ahead and shorten it.

What you are refering to us almost an urban myth from the days of CB radio. If the aerial is not matched to the cable, then altering the cable length can aparantly alter the VSWR because the missmatched cable is in effect working as a matching transformer. That was common practice by untrained folk with poor aerials back then.

 

[Salty John]

Yes, you can shorten the cable.
You shouldn't make it less than 1m long and the antenna should be no less than 1m from the radio. Otherwise, chop away.

 

[Barry Jones]

Its fine to shorten it - it is 50 Ohm impedance coax.

Make sure you put the coaxial plug on properly at the shortened end.

 

[maby]

If you are not experienced in soldering, the PL259 plugs used on most radios are quite difficult to fit correctly. They contain a lot of metal and you need a high powered soldering iron to get them up to temperature quickly. Perhaps counterintuitively, trying to solder one with a low power iron is more likely to damage the cable since you will be keeping the temperature high for a long time and there will be a serious risk of melting the insulation.

If you do intend to shorten tha cable and are not experienced with making up radio frequency connectors, do some internet research first and make sure you understand how to do it. There is a real risk of not making a good connection and you could be putting your life at risk if the connection is intermittent.

 

[Chrusty 1]

Thank you all for your replies, I was dreading having to have umpteen metres of cable stowed in a locker somewhere I am experienced in soldering, and have a large 60 watt iron that will do the trick.

Very many thanks!

Chrusty.