Radio reception problems

[PhillM]

Last year I fitted a new MTEC MT500 DSC radio and a new ariel. I tested it on install and it was working in July.

On Saturday, I noticed that I could receive fine on CH 16 but when I switched to 23 for the Weather on the Ventnor Ariel, it had a lot of background noise.

When I arrived at Berthon (where I had a very nice stay, thank you), I called in on CH80 and seemed to be received fine, but when they called me back, my reception was muffled and broken up. I then berthed in the wrong place (opps sorry ). When the boat that should have been where I was arrived, they called in to reception to ask for advice. They seemed to talk to Berthon fine, but on my radio both they and Berthon were so broken up I could not understand the words (even though I could actually see and hear the skipper of the other boat as he made his call).

To summarise:

The radio was new last year. The ariel was new this year. Both were working just fine in July / August.

I seem to transmit OK - noboady has asked me to repeat, nor have I been ignored.

I can receive on CH 16 fine

I seem to have a reception problem on CH 23 and 80 and I suspect others

Any suggestions?

 

[maby]

It's very unlikely to be a channel specific thing - the frequency range between the lowest and highest frequency channels is pretty small so, if the antenna is working on one channel, it will be reasonably well tuned on all the others. In fact, with modern receiver design, there is little scope for any fault that will affect some channels more than others. I think you need to do some more experiments to try to pin it down. Do remember that different power levels are used by default on different channels - marinas on 80, for example, are normally transmitting on low power while traffic on 16 will usually be on high power. I can often hear Oostende coastguard at (I guess) a range of close to 100 miles quite well while having difficulty copying the local marina at a range of less than 10 miles.

 

[Leighb]

Something sounds strange about your experience of Ch80. This is a duplex channel, so you should ever only hear the marina calling you, or other yachts, and never the other yachts calling the marina. If you could hear both sides of the exchange then that is not right. Unless your set is on US rather than International, when you will be able to hear other yachts on Ch80 but not , AFAIK, the marina.

CG channels for weather can be very variable, you can get clear reception on 23 (say) in one place and a mile or two away it may be very poor, sometimes you can receive one of the alternative channels better than the one you should get at that location. This is true on the East Coast at least.

 

[maby]

...

CG channels for weather can be very variable, you can get clear reception on 23 (say) in one place and a mile or two away it may be very poor, sometimes you can receive one of the alternative channels better than the one you should get at that location. This is true on the East Coast at least.

It is certainly true - and sometimes not very intuitive - I have struggled to hear the MSI broadcast on the supposedly local antenna while getting good reception on more remote antennae.

 

[DipperToo]

I had a similar issue several years ago with just 2 channels 'misbehaving' - turned out to be a fault with a Navtex receiver interfering somehow with the radio. Nasa never did say exactly what component was replaced.

 

[PhillM]

I had a similar issue several years ago with just 2 channels 'misbehaving' - turned out to be a fault with a Navtex receiver interfering somehow with the radio. Nasa never did say exactly what component was replaced.

That is interesting. I have recently wired up a FM/CD player that was disconnected when I did the rewire. Its not on the same power supply and does not have any sort of connection / splitter to the VHF. I don't think it was on at the time but I cannot be 100% sure. However, the VHF Ariel wire does pass close by, so it might be some sort of electrical interference.

The only other new electrical items are 2 cabin lights (on the same fuse as the fm/cd) and an autopilot that is wired into battery 2. Non of these were in use at the time.

 

[PhillM]

Posting this update in case anyone else gets the same problem.

Feb I radio checked with Solent CG on 16, all fine. April and yesterday I radio checked with SCG on 67, again OK.

A couple of weeks ago I called into Gins on CH68 and that worked fine.

Yesterday could not hear on ch80 or the CG weather on 23.

I changed to my emergency antenna and had the same problem - thus ruling the mast antenna and cabling out.

Spoke to the distributors today and apparently the most likely issue is the receiving crystal. CH23 and CH80 are duplex and receive on a very similar frequencies.

If the unit is under warranty then I need to send it back. If its more then 2 years old, then its beyond economical repair.

I should add that Barry at SM Group was very knowledgeable and helpful.

I will now go and dig out the log book and see when it was installed.

 

[Bilgediver]

does the screen show INT above the channel number on 23 and 80 or does it show USA? The radio could have been programmed with these channels configured as simplex.

 

[KAL]

If you're really stuck, get in touch with John at JGtechnologies - there aren't many people who would know more than him.

 

[PhillM]

does the screen show INT above the channel number on 23 and 80 or does it show USA? The radio could have been programmed with these channels configured as simplex.

Thanks for the suggestion. I checked at the weekend and it shows INT above both.