Cruisers Forum

  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
Thread Tools Search this Thread Rate Thread Display Modes
Old 02-08-2022, 16:38   #1
Registered User

Join Date: Oct 2019
Location: Seattle
Boat: Beneteau 461
Posts: 125
Send a message via Skype™ to suiramor
ICOM m803 - difference between antennas?

ICOM m803 has two outputs for antenna connection: one goes to the AT-140 and the other is described as 'HF Antenna for DSC comms'. What's the difference in use and deployment? I have the first one connected through the AT-140 to my isolated backstay. What kind of antenna do I use for the 2nd? What does it give me if it is connected? Could I connect it to the VHF antenna used by my other VHF radio (without blowing both and/or the boat up)?
suiramor is offline   Reply With Quote
Old 02-08-2022, 16:58   #2
Moderator and Certifiable Refitter
Wotname's Avatar

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 18,295
Re: ICOM m803 - difference between antennas?

The second antenna is a receive only antenna. It only functions for some DSC HF operations. It allows the receiver to continue receiving while the transmitter is transmitting.

Most times recreational sail boats do not use the HF DSC functions and most do not worry about the second antenna. The second only needs to be a long length of wire.

Do not connect it to the VHF antenna.
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 02-08-2022, 17:00   #3
Jammer's Avatar

Join Date: Jan 2010
Location: Minnesota
Boat: Tartan 3800
Posts: 4,016
Re: ICOM m803 - difference between antennas?

The second antenna is a receive-only antenna that the radio uses to monitor the frequencies used for DSC in each band. If it is not connected, the radio will not receive DSC. My understanding isn't clear on whether it will receive DSC acknowledgements for DSC messages that are sent -- the transmit goes on the main antenna, not sure about the response.

Usually people connect it to a 5' to 10' whip antenna. The antennas sold for Weatherfax use are ideal and are about 5'. CB antennas will work OK. VHF antennas are generally too short to be effective. As Wotname writes, you can also make a wire antenna.

A fact to consider is that a really good DSC antenna will receive mayday calls from a great distance, far beyond that where your vessel would be a plausible candidate for providing aid. The DSC mayday calls that you could then receive may become a distraction from other important responsibilities. In that light it is important to select an antenna that has sufficient but not excessive performance.
The difference between plans and dreams is that plans acknowledge the existence of inconvenient facts
Jammer is offline   Reply With Quote

antenna, enc, icom

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
New Icom M803 SSB gjorgensen Marine Electronics 57 29-08-2022 05:40
ICOM M803 and RigPi station server Kube Marine Electronics 2 02-12-2021 10:47
ICOM M803 maregan Marine Electronics 8 16-04-2021 11:27
ICOM IC-M803 SSB-Radio Hermia II Marine Electronics 10 11-11-2020 00:48

Advertise Here

All times are GMT -7. The time now is 15:07.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.