Vhf / Fm..

[Adam F]

Will a VHF ariel pick up an FM/AM radio signal?

[reg]

Yes it will. But don't transmit on your vhf as It will blow your vhf/am radio up. You can buy a splitter which should have a blocking gismo in it which should keep your vhf/am protected

 

Reg

[Adam F]

What if they are on seperate ariels?

 

VHF on one vhf ariel, an FM/AM radio on another vhf ariel? Logic being I can have a radio onboard, plus a spare VHF ariel should the need arise.

[reg]

if you transmit on your vhf. with the two antenna's being in close proxcimatry your vhf will overload the back end of your radio and damage it. so would be wise to switch your radio off whilst transmittig on your vhf hope this makes sense if not will phone you

 

Reg

[Paul D]

Adam,

 

Sound reasonable to me.

 

Prodigy has a twin aerial setup, so suggest you take a look at how they are rigged.

 

I can't see it being a problem as the transmitter and receiver are on different frequencies provided the separation is sufficient. ( A long time ago I could have calculated it all ).

 

However, I have just read Reg's note and he has a point, although I suspect that this will not damage the radio as the distance is sufficient ( along with diff freqs ).

 

Otherwise you would be destroying your GPS every time you transmit.

 

I would checkout Prodigy.

 

[Paul D]

Was interested by this post, so have done some studying.

 

The antennae need to be at least 1/4 wavelength apart ( which in the case of VHF is 1/2 metre or around 19 inches ) and then spaced at odd number of 1/4 wavelengths ( for max attenuation between them ).

 

eg. 19 inches apart good

38 inches apart ( 1/2 wavelength ) bad

57 inches apart better

 

I would recommend against having 2 marine VHF sets connected ( ie. one to each antenna ) - but that was not your plan.

 

Actually, on Neo I have two aerials - one "rubber duck" style one and the VHF one.

 

[Sam]

yeah but knowing gary he just has to of everything for the sake of it because he can

 

sam

[Brian]

I've got 2 VHF aerials approx 14" apart, both connected to VHF radios (an ICOM and a Huson).

Both sets are usually switched on, I've never had any trouble regardless of which set I transmit on, even on 25w (although the sets are not usually on the same frequency). I've also got a car radio connected to a CB aerial, which doesn't mind me transmitting on the VHF.

The front end of a VHF radio should be designed to handle it without overloading.

Edited March 17, 2007 by Brian