Re: [Amel Yacht Owners] Re: Icom M802 and AT140 tuner grounding


Herbert Lackner
 

Good Morning to all,

Alans 2nd option was what I wanted to explain :-)

On our SN we do not have a separate HF ground (I think this was an option that the first owner did not order from amel), the copper foil is connected to the yellow green line and therefore to the rudder.... Maybe all SMs have the the separate HF ground?

So to prevent any grounding problems I choose the solution to put the capacitors in between the tuner ground and the copper foil (in serial, that means that there is no DC connection between the tuner ground and the copper foil, the capacitors will block any DC currents but will let HF through).

The SSB itself will not be grounded in a normal installation. Sometimes it has to be grounded, when problems (like HF burn when touching the SSB during transmitting, you will find out if you have these problems ;-) ) occur, and then you should also use the capacitors (serial) when connection the ssb ground.  Before you do that you should check your ssb installation to eliminate other reasons for these ssb problems before you ground the ssb (this is in my opinion only the last option).

In some SSB installation manuals you can read that the ground has to be connected but this is normally not true on a sailboat, It is true on a standard land based installation in the shack at home.

in my Kennwood the -12V that goes to the SSB (from the battery, we have a 12v system) is directly connected to the Coax antenna shield that goes to the tuner, therefore blocking DC current at the tuner ground is absolute necessary to avoid to have a dorect connection from the battery to the Amel grounding system.

The capacitors are solded together in parallel so that it is like one big capacitor with two legs, it is installed as a blocking element in serial (cut the old cable and put the element in between).

Hope that makes it more clear what I tried to say

Herbert
KALI MERA, SN 120
Kusadasi

Am 07.06.2014 um 03:54 schrieb "divanz620@... [amelyachtowners]" <amelyachtowners@...>:

 

I think Herbert means that you can use the ships earth to make your SSB ground even better, as long as you isolate any DC current from it and you can do that by wiring 10 3900pf capacitors in parallel between the SSB ground and the ships earth - you actually have 20 connection points, 2 for each capacitor ! - the capacitors will conduct Hi frequency AC (your radio signal) but block any DC component.

But you still don't connect your 802 ground connection to ships ground.

And you still need an isolated power supply, or use the relay system I posted to keep the DC off the SSB ground...other wise that will come back through the seawater to your ships ground.

OR

Capacitors can also be used in the SSB ground with the same effect, to keep DC current from entering the seawater.....break the SSB ground connection after the tuner...between the tuner and the SSB ground plates.....best place is the copper foil....cut it across so there is no connection, and then solder 10 of those caps across the gap, side by side (ie in parallel)


Cheers

Alan

SV Elyse SM 437, Papeete

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