Radio mystery

[nimbusgb]

Bit of a strange problem.

icom- IC-M505 panel mounted DSC VHF. It appears not to be communicating on 'international' channels such ie 80. But certainly seems to be working on regular channels. Brighton marina and a handheld on ch80 don't even break squelch when the 505 is keyed but reception seems OK. Bit odd. Any ideas? Has the radio slipped into some weird mode or are 2 of us being complete numpties?

 

[rob2]

Sounds like a RTM moment! I don't know the 505 as such, but all Icoms can be set to European (International) or US channel specs. There are differences between the specs with some simplex channels becoming duplex, etc, so you won't receive anything if the set has accidentally been set to the US spec and several commonly used UK channels are actually "private" channels only included on UK sets.

Assuming it is a locally sourced (UK) set and has worked in the past, have a look at setting it to the International spec.

Rob.

 

[neilf39]

I thought this was to do with simplex and duplex channels. You cannot talk between two ship radios on 80 as it is duplex so the marina transmits on a different frequency to the ship VHF. Ship to ship channels are all simplex. So for example if you broadcast on the handheld on 80 your fixed radio won't receive it but the marina will. If the marina braodcasts you will hear it on both.

 

[VicMallows]

CH80 in the UK is a duplex channel (transmit and receive on different frequencies). This means you can hear the base station (marina) but not another boat transmitting on that channel. In the US, CH80 is a simplex channel, and on a US radio in the UK you would hear another boat, but not the marina!

Is it possible your VHF has become set in 'US' mode?

CH80 is also probably the only duplex channel you use, so a fault related to duplex/simplex is also a (less likely) possibility.

Edit: sorry ROB2 - slow typing! As an aside: using a duplex channel as the primary marina channel seems unfortunate, resulting in numerous 'clashes' at busy times since boats do not know another boat is transmitting - often to a different marina they can not hear. (It is of course a left-over from the duplex channels originally allocated for the now defunct ship-shore service).

 

[nimbusgb]

CH80 in the UK is a duplex channel (transmit and receive on different frequencies). This means you can hear the base station (marina) but not another boat transmitting on that channel. In the US, CH80 is a simplex channel, and on a US radio in the UK you would hear another boat, but not the marina!

Is it possible your VHF has become set in 'US' mode?

CH80 is also probably the only duplex channel you use, so a fault related to duplex/simplex is also a (less likely) possibility.

Edit: sorry ROB2 - slow typing! As an aside: using a duplex channel as the primary marina channel seems unfortunate, resulting in numerous 'clashes' at busy times since boats do not know another boat is transmitting - often to a different marina they can not hear. (It is of course a left-over from the duplex channels originally allocated for the now defunct ship-shore service).

I did check ( several times ) that we are in international not US mode but I'll do it again. The fact that we can receive fine on simplex channels leads me to think that perhaps it's just an antenna fault. I'll drag out my SWR meter and see if we get a decent reading.

 

[wooslehunter]

This may help to work it out.

In the UK, a ship radio when on Ch80 will transmit on 157.025MHz (the A frequency) & listen on 161.625MHz (the B frequency). A shore station is opposite. In the US, both stations transmit & receive on A.

Receive Transmit
UK Ship B A
UK Shore A B

US Ship A A
US Shore A A

So if your radio is in duplex UK mode, you should be able to hear & talk with a shore station but you will not hear a ship station. Handhelds are generally set as ship radios so you will not hear one on CH80.

If your radio has been set to the simplex US configuration, you will not be able to hear a shore station. However, you should be able to hear the handheld.

You're right to check the antenna. Can you communicate with distant stations on simplex channels?

 

[VicS]

If your radio has been set to the simplex US configuration, you will not be able to hear a shore station. However, you should be able to hear the handheld.

But the h/h will not hear the the fixed set.

Normally you should NOT be able to communicate between the fixed set and the H/H on Channel 80 if they are set to the International channels used in the UK because it is a ship to shore channel.
Communication will only be possible on the single frequency channels eg Ch 06 and the other inter-ship channels

There are about a dozen other channels that will be similarly affected if the radio has been set to the US channels

 

[laika]

I had had my IC-M33 HH for a few years before I used it in the UK to call a marina for the first time. It wasn't receiving on 80 (marina could hear me but I could only hear them reply through the speaker on the fixed VHF, not on the HH). I checked and re-checked that it was set to international, then talked to ICOM who told me to send it back to them. Turned out to be a fault which they fixed free of charge (even though it was outside warranty) and couriered it back to me a few days later. I've been searching old emails for the details but to no avail (sorry).

Bottom line: could be worth a chat with ICOM if you're positive it's not set to US and all other ideas prove fruitless

 

[Bilgediver]

Bit of a strange problem.

icom- IC-M505 panel mounted DSC VHF. It appears not to be communicating on 'international' channels such ie 80. But certainly seems to be working on regular channels. Brighton marina and a handheld on ch80 don't even break squelch when the 505 is keyed but reception seems OK. Bit odd. Any ideas? Has the radio slipped into some weird mode or are 2 of us being complete numpties?

Sounds like it has slipped to simplex mode IE transmitting and receiving on the same frequency. If you can put the HH on USA channels then try a test. If both radios hear each other then this will conform it has slipped to USa channels. Have you tried setting it to USA and then resetting it to International?