Triatic, and use for SSB (DSC receive only)


David Vogel
 

Hi Bill,

 

Thanks for the extra info about the release timing of the M802, viz SM#396 (built late 2002, commissioned Feb’03).  That the HF is likely an after-sale install makes sense.

 

Subsequent research reveals that the IC-M802 has 2 receivers - this is, apparently, so that the unit can receive DSC emergency calls while the main receiver is in use (for voice or digital, such as via a PACTOR or other data modem).

 

Accordingly, the M802 has two jacks for coax cables: the first jack is for the coaxial cable to the antenna tuner; the second jack is for the DSC antennae, which is used only to receive DSC calls.

 

Sending DSC messages uses the transmitter, which uses the main (first) jack to the antennae tuner (and beyond).  The DSC jack, coax, and RX-only antenna is not used for transmitting – so, the triatic (in my case) need not be capable of accepting the transmitted power.

 

Whether anyone actually uses DSC on their HF set, probably not in recreational use.  I have tried to set up a DSC HF net once or twice, but it quickly gets pretty messy, and the good old regular time-based voice SKEDs on agreed frequencies seem to work fine, without all the complication – the power consumption in DSC mode is quite low, apparently.  BTW, I have received a few DSC emergency and urgency calls whilst out in the wild blue yonder – I just happened to have the HF set on, albeit with the volume down, and the alarm at 3am was quite startling.

 

I hope this provides further clarity to the discussion.

 

With best regards,

 

David

SM#396, Perigee

NZ

 

 

From: <main@AmelYachtOwners.groups.io> on behalf of Bill Kinney <cruisingconsulting@...>
Reply to: <main@AmelYachtOwners.groups.io>
Date: Monday, 8 August 2022 at 12:21 pm
To: <main@AmelYachtOwners.groups.io>
Subject: Re: [AmelYachtOwners] Bonding and Grounding Checks [Re: Triatic , and use for SSB.]

 

David,

I am pretty sure the  802 was not yet on the market when your boat was built, so its wiring is aftermarket. Amel's original purpose for rigging the triatic as an antenna was for feeding a signal to the weatherfax receiver that was an optional feature on the Super Maramu.  With standalone weatherfaxes now pretty much obsolete, its use as a DSC signal receiver for the 802 is a good one. 

But does anybody actually uses SSB DSC?

The triatic's location and configuration would make a poor choice for a primary high power send and receive antenna for an SSB.

As a VHF antennea, I'd be skeptical.  Its length would probably make it a very high gain antenna, unfortunately not focused in a useful plane.  It would broadcast and receive in a plane perpendicular to the length of the wire... pretty much straight up and down. Maybe good for communicating with satellites, but not other boats.

Bill Kinney
SM160, Harmonie
Port Louis, Grenada
http://www.cruisingconsulting.com