VHF Duplex

[siencyn]

Hullo, I wonder if anyone can tell me why my handheld has suddenly decided not to hear the shorestation I call on channel 18 whilst I can still hear other vessels calling that shorestation? I could hear both until recently. Also, my fixed dsc vhf does the opposite to the same station!! I can hear the station but not the vessels. Have I inadvertently pressed the wrong buttons somewhere? Many thanks

 

[[3889]]

Not sura about 18 but some channels, such as 80, are simplex in US and duplex on international settings. Have you switched between US and international or vica versa?

 

[VicS]

Channel 18 is a "duplex" channel. The shore station transmits on 161.500 MHz and the ship station transmits on 156.900.

Normally then you will hear the shore station but not the ship station as you do on your fixed set. It may be possible for the shore station to re-transmit the ship's transmissions on 161.5 then you will hear both. The old coast radio stations used to do that.

You should check the instructions for your portable to see if it can be switched to reverse the frequencies.

 

[Rowana]

According to the blurb that I have, Channel 18 is a duplex channel on the international frequencies. Tx is on 156.9Mhz and Rx is 161.5Mhz.

If your radio is set to USA channels, both Tx and Rx are 156.9Mhz.

Someone more up to speed with VHF frequencies than I am may wish to comment on this. I'm only reading from what I have to hand.

I suggest you check your radios are both set to international frequencies, and use a different channel.

 

[Rowana]

I've been Lakesailored!

You must have been replying as I was typing.

It's nice to know I was correct anyway !

 

[VicS]

[ QUOTE ]
I've been Lakesailored

[/ QUOTE ] But I did not know about the US frequencies. I reckon you have got the answer there. The radio has been switched to the US frequencies!

 

[Rowana]

[ QUOTE ]
But I did not know about the US frequencies. I reckon you have got the answer there. The radio has been switched to the US frequencies!

[/ QUOTE ]

That's what it sounds like to me as well.

I have a list of the International, USA & Canadian frequencies that came in the back of my vhf manual, and I was quoting from that.

 

[siencyn]

Many thanks everybody. That sounds like the answer. I can't think how but the channels much have switched. I'll check it out. Thanks again guys.