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Old 30-03-2014, 10:20   #1
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SSB grounding on a steel hull

Just committed to a SSB as we finish our steel hulled sailboat - went thru what I can find on grounding, and still have a couple questions. SSB is a Icom M802 with a AT140 tuner. Will use 3" wide copper foil to run to a convenient bolt to the hull.

BUT
- we have a common grounding point for every other DC item onboard - which includes the engine block - do I take the SSB ground there, or avoid it?
- if we do avoid - do the transmitter and tuner grounding point need to be common?
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Old 30-03-2014, 10:33   #2
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Re: SSB grounding on a steel hull

Its an arguable subject, but I would run copper foil from the tuner ground to a nearby bolt, but with blocking capacitor(s) in the circuit to block DC current. I would NOT connect the radio ground.

DC Blocking Capacitors

Steel Boat Ham Radio Antenna Installation
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Old 30-03-2014, 10:43   #3
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Re: SSB grounding on a steel hull

Quote:
Originally Posted by nofacey View Post
Just committed to a SSB as we finish our steel hulled sailboat - went thru what I can find on grounding, and still have a couple questions. SSB is a Icom M802 with a AT140 tuner. Will use 3" wide copper foil to run to a convenient bolt to the hull.

BUT
- we have a common grounding point for every other DC item onboard - which includes the engine block - do I take the SSB ground there, or avoid it?
- if we do avoid - do the transmitter and tuner grounding point need to be common?
The SSB tuner does not need to connect to DC ground. In fact it's a good idea to put a DC blocking capacitor in the SSB tuner ground foil if the tuner does not provide it (AT140 does not). That way no DC current can flow into/out of the hull via the tuner ground.

Ideally, the SSB transceiver unit should be connected directly to the batteries by way of a properly sized fuse or circuit breaker in the + lead. There is no need to connect the - lead to a "common ground". Best to connect the radio power leads to where the current comes from and must get back to which are the battery terminals. If you have a negative shunt for a battery monitor then connect the radio minus to the side of the shunt away from the battery negative.

SSB radios draw significant current (>20A) and if this current flows in a wire shared by other instruments it can cause strange problems. That's why I recommend dedicated wires of the right size direct to the battery bank.
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Old 30-03-2014, 10:57   #4
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Re: SSB grounding on a steel hull

Thx for the very clear response gentlemen! - one of your links included an excellent Practical Sailor grounding summary, which I've brought forward below.
Grounding
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Old 30-03-2014, 15:38   #5
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Re: SSB grounding on a steel hull

The Icom AT-140 tuner has blocking capacitor built-in. No need for another one. Connect it directly to the hull.

Do NOT connect the radio separately to any ground.

The advice about proper wiring is good: the 802 draws up to 30A on transmit. Wire the radio to the house batteries with AWG6 for one-way runs up to 20 feet, AWG4 for longer runs. Fuse BOTH the positive and negative cables as near to the batteries as possible, using ANL or MRBF fuses.

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Old 30-03-2014, 17:03   #6
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Re: SSB grounding on a steel hull

Bill,

I tried to get an answer about the AT140 some months back as to the DC block in the ground. I could not find definitive proof it has it. I know you are very experienced. Can you tell us which Icom tuners have the internal DC blocking in the RF ground terminal?
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Old 30-03-2014, 17:54   #7
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SSB grounding on a steel hull

Quote:
Originally Posted by transmitterdan View Post
Bill,

I tried to get an answer about the AT140 some months back as to the DC block in the ground. I could not find definitive proof it has it. I know you are very experienced. Can you tell us which Icom tuners have the internal DC blocking in the RF ground terminal?

Here's the schematic for the 130 E/140

http://www.ko4bb.com/Manuals/ICOM/AT...ice_Manual.pdf

I don't see blocking caps on the rf gnd connection ( mp 23 )


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Old 31-03-2014, 06:02   #8
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Re: SSB grounding on a steel hull

Single point ground everything including your SSB ground. DC current leakage on a steel hull is a non issue. If your electrodes are being eaten away, you have faulty equipment or other issues that need to be sorted out. Do not worry about grounding your tuner to your single point ground and dont waste your time and money with rubbish capacitors that have probably failed on most yachts where they have been installed. Besides its so easy to measure and check for these currents with a simple multimeter. Single point grounding or equipotential bonding is the best thing you can do on a yacht from a RF, safety, lighting and electrolysis point of view. The last thing you want to do is install a useless set of capacitors that achieves nothing in the real world and will only expose your boat and its electronics to more problems.
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Old 31-03-2014, 06:20   #9
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Re: SSB grounding on a steel hull

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Single point ground everything including your SSB ground
Your RF ground is a counterpoise, I would not connect it to DC anything.

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Old 31-03-2014, 06:40   #10
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Re: SSB grounding on a steel hull

You dont understand the subject matter, you are really badly informed about electronics and RF I am sorry to say.


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Your RF ground is a counterpoise, I would not connect it to DC anything.

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Old 31-03-2014, 07:29   #11
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Re: SSB grounding on a steel hull

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You dont understand the subject matter, you are really badly informed about electronics and RF I am sorry to say.
I understanding both DC grounding systems and RF grounding on steel vessels , much better then you do.

For best results , DC systems on a steel boat should be preferably floating, with NO AC earth connection if there is a shore power fitment ( and I don't care a hoot what ABYC thinks) a DC inert hull is best if it can be obtained. Because of that the concept of equipotential grounding is a further misnomer.

Furthermore ICOM particularly make it clear that RF ground and DC ground should not be connected


On fibreglass system, I prefer no bonding of underwater fitments, it causes more trouble then its worth and unbounded is common in European fibreglass boats.

RF ground should have DC blocking caps where those grounds are making use of an underwater fitting, purely capacitive contact of course will not require such fitment.

DC ground is of course a misnomer, as its a DC return path. A ground is a connection to earth ( even though in electronics the two are often used mistakenly )

and to boot I'm a Ham operator


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Old 31-03-2014, 07:48   #12
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Re: SSB grounding on a steel hull

Quote:
Originally Posted by transmitterdan View Post
Bill,

I tried to get an answer about the AT140 some months back as to the DC block in the ground. I could not find definitive proof it has it. I know you are very experienced. Can you tell us which Icom tuners have the internal DC blocking in the RF ground terminal?
transmitterdan and Dave:

Sorry guys....I may have erred in saying the AT-140 has built-in DC blocking capacitors. I thought I remembered that Icom was now installing blocking capacitors in their AT-130 and AT-140 tuners -- much as the SG-230 has had for years -- but maybe not.

Just tested a newish AT140 in my shop and find that there is a direct DC connection between the barrel of the SO-239 connector and the ground post on the tuner. So....no DC blocking capacitor there.

Perhaps Eric can fill us in on the latest news, as he works on these all the time.

BTW, I also tested two other tuners: one from SEA and one from Kenwood (MAT-100). Neither have DC blocking capacitors.

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Old 31-03-2014, 08:14   #13
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Re: SSB grounding on a steel hull

Quote:
Sorry guys....I may have erred in saying the AT-140 has built-in DC blocking capacitors. I thought I remembered that Icom was now installing blocking capacitors in their AT-130 and AT-140 tuners -- much as the SG-230 has had for years -- but maybe not.
Yes I had a look through the circuit diagram, which of course is not a reliable way of determining anything!, didn't seem to exist on them anyway.


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Old 31-03-2014, 18:04   #14
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Re: SSB grounding on a steel hull

Bill,

Thanks for checking for us. The SGC tuner has internal blocking C and I think that is a plus for that unit. But adding it to the Icom isn't difficult.

Thanks,
Dan
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Old 02-04-2014, 03:29   #15
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Re: SSB grounding on a steel hull

Only sailors think they have different grounds. AC, DC, RF there is only one ground reference. AC, DC or RF would not care about the special care you took to give your ground a "special" name. The reality is that its the same reference despite what you want to call it. DC return path, AC return path antenna current return path. Its one and the same. Floating works well for birds sitting on power lines. In the real world of RF, lighting and electricity you better bond your grounds. Now if you think hard, you will one day realize that you DC ground and RF ground are always connected despite all the special measures you take to isolate them. You thinking is flawed also when you talk about separating or floating grounds from a lighting protection point view. A guaranteed way of maximizing lighting damage is to practice what you preach. I am sorry to say your thinking is flawed and every electrical safety code says so before we even begin to talk about the RF ground. The main reason you do want to bond all your ground is to minimise common mode and differential mode noise. We will just have to disagree and leave it at that, good sailing and hamming.
Quote:
Originally Posted by goboatingnow View Post
I understanding both DC grounding systems and RF grounding on steel vessels , much better then you do.

For best results , DC systems on a steel boat should be preferably floating, with NO AC earth connection if there is a shore power fitment ( and I don't care a hoot what ABYC thinks) a DC inert hull is best if it can be obtained. Because of that the concept of equipotential grounding is a further misnomer.

Furthermore ICOM particularly make it clear that RF ground and DC ground should not be connected


On fibreglass system, I prefer no bonding of underwater fitments, it causes more trouble then its worth and unbounded is common in European fibreglass boats.

RF ground should have DC blocking caps where those grounds are making use of an underwater fitting, purely capacitive contact of course will not require such fitment.

DC ground is of course a misnomer, as its a DC return path. A ground is a connection to earth ( even though in electronics the two are often used mistakenly )

and to boot I'm a Ham operator


Dave
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