Crazy problem - VHF handset sets off Systems Monitor audio alarm

[ZZ13]

This is really strange. When I bought the boat in November the Ray220 VHF handset didn't do anything. Took the connector apart and found 3 wires broken off. Sent it to Raymarine for a $75 repair and it came back looking all brand new and working perfectly. Also, the Systems Monitor display was dead so I bit the bullet and forked out $740 for a new Systems Monitor display unit. It works perfectly now. The Systems Monitor display unit is mounted directly above the VHF radio. So here's the crazy part. Whenever I depress the handset PTT button for more than a few seconds, the audio alarm on the Systems Monitor sounds and keeps going until I push the button on it to turn off the alarm. Anyone have any ideas on this one?

 

[Alex F]

Bill, what's the message on the monitor say? This is a weird one. I don't think there's any connection between VHF wiring and the System Monitor.

 

[ZZ13]

No message at all Alex other than the all systems normal message. Just the audio alarm. I am thinking some kind of RF or EMI that happens to trigger the buzzer circuitry in the Systems Monitor. When Prince William Marina made the push to sell off their used parts a few months ago I picked up a spare Ray220 unit. Going to try swapping it in and see if the problem remains.

 

[sdarc]

I think you're correct in that it is RF or EMI. The wires in the VHF are most likely not shielded.

 

[my3sons]

Bill, I have no trouble believing that. When I replaced the DDU on the 360, the VHF would get static on some channels. Wouldn't do it If the nav or anchor light was on. Sea Ray sent me another DDU, but it was the same. apparently some of the new DDU's don't play well with others.
My frustrations with the systems monitors are never ending it seems, the one on the 400 is not 100% either. good luck

 

[ZZ13]

Bill, I have no trouble believing that. When I replaced the DDU on the 360, the VHF would get static on some channels. Wouldn't do it If the nav or anchor light was on. Sea Ray sent me another DDU, but it was the same. apparently some of the new DDU's don't play well with others.
My frustrations with the systems monitors are never ending it seems, the one on the 400 is not 100% either. good luck

I saw the exact same Systems Monitor DDU was on the brand new 650 Fly when I was on it. I was surprised to see its still around as a factory install item.

If I don't solve this, guess I gotta keep my transmissions short and sweet.

 

[JimFromMD]

It does sound like RF interference. My old neighbor in Annapolis was a ham radio operator and durring a hurricane he was blasting out some high power signal. Ended up setting off the smoke alarm system in a new house a few doors down.

Does it happen if you put your VHF on low power for transmitting... or if you put your VHF handheld on high/low near it?

 

[ZZ13]

It does sound like RF interference. My old neighbor in Annapolis was a ham radio operator and durring a hurricane he was blasting out some high power signal. Ended up setting off the smoke alarm system in a new house a few doors down.

Does it happen if you put your VHF on low power for transmitting... or if you put your VHF handheld on high/low near it?

I had no idea I could configure it that way James. I will give it a try. If that doesn't work you'll have to take a road trip and check it out for me.

 

[JimFromMD]

I had no idea I could configure it that way James. I will give it a try. If that doesn't work you'll have to take a road trip and check it out for me.

There's usually a high/low button that drops you from 25 watts to 1 or 5 on base units... and on handhelds its usually from 5-6 watts to 1 watt. Theory being that if you are in a harbor, you aren't blasting the input side of everyone's receivers, and also leaving the communication channel more open for others who aren't nearby. High power for longer distance communications or out in more open water when you need the power to reach. Or another analogy, everyone in a room shouting stepping on each other vs quiet side conversations. Reality is most of us (including me) forget to drop to a lower power setting when it makes sense to do so.

If it ends up being a RF interference issue, you may be able to put some shielding around your radio or on the back of the monitor unit to attenuate the signal/signal bleed some.

Road trip? Sounds good to me!

 

[ZZ13]

There's usually a high/low button that drops you from 25 watts to 1 or 5 on base units... and on handhelds its usually from 5-6 watts to 1 watt. Theory being that if you are in a harbor, you aren't blasting the input side of everyone's receivers, and also leaving the communication channel more open for others who aren't nearby. High power for longer distance communications or out in more open water when you need the power to reach. Or another analogy, everyone in a room shouting stepping on each other vs quiet side conversations. Reality is most of us (including me) forget to drop to a lower power setting when it makes sense to do so.

If it ends up being a RF interference issue, you may be able to put some shielding around your radio or on the back of the monitor unit to attenuate the signal/signal bleed some.

Road trip? Sounds good to me!

I'd like to try shielding the antenna connector at the back of the VHF. What would I wrap it with to best try to do that?

 

[ZZ13]

Went back to the boat and did some more debug. It was set at 25W, so I tested it again as is. Alarmed the DDU just like before but this time also the two lines filled up with a bunch of "e", "w", "u" characters and maybe a few more. Seemed to get the DDU into a non-recoverable state. I had to cycle power to it reset it. The interesting thing is since I cycled power, I can't get it to fail anymore either at 25W or 1W of power.

James, my unit seems to have only a 1W or 25W selection. Nothing inbetween.

 

[JimFromMD]

Went back to the boat and did some more debug. It was set at 25W, so I tested it again as is. Alarmed the DDU just like before but this time also the two lines filled up with a bunch of "e", "w", "u" characters and maybe a few more. Seemed to get the DDU into a non-recoverable state. I had to cycle power to it reset it. The interesting thing is since I cycled power, I can't get it to fail anymore either at 25W or 1W of power.

James, my unit seems to have only a 1W or 25W selection. Nothing in between.

I think that's standard Bill. I couldn't remember off hand if base units drop to 1 or 5 watts from 25. I know the handhelds go from 5 or 6 watts (depending on the units peak power output) to 1 watt for low power. Sounds like the "reboot" may have been it then? Keeping my fingers crossed for ya, though still not ruling out a road trip later this year!

 

[ZZ13]

I think that's standard Bill. I couldn't remember off hand if base units drop to 1 or 5 watts from 25. I know the handhelds go from 5 or 6 watts (depending on the units peak power output) to 1 watt for low power. Sounds like the "reboot" may have been it then? Keeping my fingers crossed for ya, though still not ruling out a road trip later this year!

Do the road trip. Something else will break sooner or later that I will need you for.