How do I use SWR meters?

Nos4r2 · 16 October 2006, 23:07

How do I use one on a marine VHF? I can't see any way of adjusting the ariel like I could on my CB.

My ariel is one of these :-

jwalker · 16 October 2006, 23:37

Nos, if the manufacturer has done their homework, you shouldn't need to. The SWR of the antenna will be known and is often quoted in the antenna literature. Knowing the SWR, it's good to check your system to confirm it is close to the manufacturer's specs.

If you're going to start fiddling, maybe add a wee bit before you get out the wire cutters. It'll give you a clue before you make the first cut.

Nos4r2 · 16 October 2006, 23:44

Yeah I didn't think I'd need to (swr quoted as 1.2) but I'm tempted to get a meter and check it.

CB gear was always supplied for you to set up yourself. I guess it's not really realistic to do that on a marine ariel anyway.

jwalker · 16 October 2006, 23:51

Quote:

Originally Posted by Nos4r2

swr quoted as 1.2

Fek, that's good.

Quote:

...but I'm tempted to get a meter and check it.

If you've still got your CB one, you may be surprised how accurate it is although the frequency is entirely wrong.

Nos4r2 · 17 October 2006, 02:25

I was looking on ebay-there's SWR meters for 1.5-200mhz on there. Most CB ones only go to 30mhz-which is all my CB one does. It's not rated for more than 4w either.

jwalker · 17 October 2006, 09:32

Quote:

Originally Posted by Nos4r2

Most CB ones only go to 30mhz-which is all my CB one does. It's not rated for more than 4w either.

I know but try it just the same. I have an Altai one (well I did have, it's on loan at the moment - hint

) and it's surprisingly accurate. If you're looking at pucka meters, you'll need the appropriate xtals. 4watt is fine. Just set the radio to 1watt.

Jon Brooks · 17 October 2006, 12:49

There is nothing to adjust on a marine antrenna.
Most these days are set up to work spot on the marine channels.

Having a VSWR meter is always hady to check if you are having troubles.

It can tell you if there is a fault on your set up.
Only trouble is that the trouble could be with the Plug, the co-ax, antenna or a combination of all.

Regards

Biggles · 17 October 2006, 13:08

Matt,

I used to have an antenna like that. It was older and more worn. Main problem with it was that the antenna (springy/whippy aerial bit) came away from the base, its only held in with a little grub screw which in my case had become worn over time. It was lost at sea. Try as I might I could not get a replacement without buying the whole thing. Might be worth taking the antenna out and making a little groove where the grub screw sits. This should be less likely to let it fall out then. As always hindsight is a great thing.
Just a word of warning on a little design fault.

Nick.

Nos4r2 · 17 October 2006, 14:04

Cheers guys.

The whip seems to be bonded in so it's not coming out but I'll heed your warning there Nick and keep an eye on it-cheers.