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Old 06-01-2011, 12:39   #1
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SSB Turns On My Inverter !

Not sure whether to post this here or in the Communications section....

I have a Xantrex Freedom 20 Inverter charger and also an SSB (ICOM 802, but that's probably irrelevant).

Whenever I use the radio, especially for packet, the inverter turns on creating enough RF noise to break the link.

I have grounded the tuner and the radio to the keel and put (substantial)ferrites on the control link between the inverter, but still no joy. In fact it still happens even if I disconnect the control link. I initially thought that it must be RF getting into the control lines, but it seems to be getting directly to the control PCB in the inverter.

I've tried earthing the Radio to the AC ground, but that doesn't help either.

Anyoine else seen this ?

Duncan
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Old 06-01-2011, 12:41   #2
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How are you powering your 802? Direct from the house batteries (as it should be), or is it connected thru a panel?

Bill
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Old 06-01-2011, 13:04   #3
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A slight amount of oxidation on an electrical connection can form a diode that detects any RF making it a problem. I would isolate both radio and inverter wiring as much as I can, also be alert for parallel runs of wire that can induce RF. Did you try ferrite coils on the power leads??
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Old 06-01-2011, 13:11   #4
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Yep, that happens. Remove the ground between the radio and the tuner (it's totally unnecessary). Make sure there is NO DC ground connection to the tuner. IE, The tuner should NOT be grounded via foil or other means to the ships dive plate or bonding. The radio's ground plane must be isolated from the DC ground or you'll get all kinds of issues. Buy yourself a copy of the "Icom 802 Manual for Idi-Yachts". Here is a solution that works the best:About Us
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Old 08-01-2011, 10:20   #5
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Hi all.

Bill, the main DC leads from the battery come to a panel as big 4/0 cables then get distributed. that's where I tied in.

Seahunter, from what I can see the outer coax braid carries a DC ground path to the tuner whether you like it or not. Am I wrong here ? I have NO direct DC path from the tuner to the keel bolts as I have a home made DC block in the foil. I DO currently have the radio grounded also to the keel bolts, but when it wasn't it didn't seem to make any difference.

Duncan
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Old 08-01-2011, 10:44   #6
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Duncan,

Big 4/0 cables to the panel? That's very unusual. Is the inverter also powered from the panel? That would be the only reason I can think of in using such heavy cables to the distribution panel, unless the batteries are 50' away!

Still, it's a good idea to power the radio directly from the house batteries, using AWG6 cable up to 20' one-way runs, or AWG4 cable if longer. There should be a 30 amp fuse in both the positive and the negative cables, located close to the batteries.

One important reason for going direct to the house batteries is that they act as giant capacitors, helping to filter out conducted RFI in both directions (from the transmitter to other instruments, and from other equipment onboard back to the radio).

The note about not grounding your radio directly is a good one, despite the instructions you'll find in many manuals. This can cause ground loops of RF (which is AC) and be troublesome. Better not to ground the radio.

Try to keep the coax between the radio and the tuner away from other wiring if possible. Also, I've found that using RG-214 double-shielded coax is helpful in reducing RFI. You might also try some heavy ferrites and, possibly, an isolator such as the one made by Radio Works installed in the coax near the tuner.

Finally, it's best not to connect the tuner ground to your boat's DC ground system, or bonding system, or lightning protection system. A short run from the tuner ground to the nearest bronze thru-hull -- which is not otherwise connected to any grounding system -- would be sufficient.

Also, some have found that the use of the KISS-SSB radial grounding system works wonders for eliminating RFI in instrumentation. The Nordhaven folks have adopted this system, and I've found it works well.

Bill
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Old 08-01-2011, 11:59   #7
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Quote:
Originally Posted by duncan_ellison View Post
Hi all.

from what I can see the outer coax braid carries a DC ground path to the tuner whether you like it or not. Am I wrong here ? I have NO direct DC path from the tuner to the keel bolts as I have a home made DC block in the foil. I DO currently have the radio grounded also to the keel bolts, but when it wasn't it didn't seem to make any difference.

Duncan
My guess is that the inverter is picking up stray DC- and wants to do a self test. Make sure all the grounds are good on the inverter. The issue is with the ground. There are three components to the radio. The head, the transceiver and the tuner. The + side should be direct from a battery source to a breaker beside the radio head and power the transceiver. The - should be directly from a battery source. This is the only ground required for the radio. The ground between the transceiver and the tuner should NOT be connected. At NO time must the ground plane and the radio ground or the ship's ground be connected. The ship's ground is connected to the radio -. The - on the tuner is NOT connected internally to the ground plane terminal so the ground plane terminal MUST be connected to a counterpoise or a separate ground plane plate isolated from the ship's electrical system (DC-) ground as per the tuner manual.
The solution:
A counterpoise ground plane. About Us
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Old 10-01-2011, 05:29   #8
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The - on the tuner is NOT connected internally to the ground plane terminal
If this is an Icom tuner, yes, the negative power feed is connected internally to the ground plane terminal. There are no DC blocking capacitors like you would find in an SGC tuner.

Eric
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Old 10-01-2011, 09:23   #9
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If this is an Icom tuner, yes, the negative power feed is connected internally to the ground plane terminal. There are no DC blocking capacitors like you would find in an SGC tuner.
Please refer to page (i) of the Icom AT-140 manual:
"DANGER HIGH VOLTAGE! NEVER touch
the antenna terminal, ground terminal, antenna or
counterpoise while transmitting. Place the AT-140, antenna
and counterpoise in positions where no one can
touch them.
NEVER use without a ground connection.
NEVER transmit during internal adjustment. This may
cause an electric shock.
USE the ground terminal for ground connection.
The mounting plate is not connected internally.
"

Page (2)
IMPORTANT! The mounting plate is NOT connected
to the AT-140’s internal ground.
Undesirable ground points
AVOID the following points, if possible. These connections
may cause noise or electrolysis:
Engine block
– Ship’s DC battery ground

Quoted from "ICOM802 for IDA-Yachts" the manual ICOM refers to as the best source of information on their product; Page (16):
Ignore the diagram (from the Icom manual Fig. 2.10) connecting a copper strap between the transceiver and the tuner can cause a problem called a "ground loop". Leave it off!"

Please read or re-read the manual before commenting. Thanks
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Old 10-01-2011, 10:12   #10
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Please read or re-read the manual before commenting. Thanks
Read it many times, read the service manual many times, have repaired many of these tuners. The negative DC feed (black wire in the 4-conductor transceiver to tuner cable) is connected internally to the RF ground stud via the circuit board ground plane. There is also a DC path through the coax shield. The only way to isolate the external RF ground plane is to use an external capacitor block.

Eric
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Old 10-01-2011, 10:35   #11
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My quotes were and are a direct copy-paste from the manual. Are they lying? And if they are connected, why tell you on the next page NOT to connect it to the DC battery ground? Answer: because the tuner draws its DC- from shielded ICOM OPC-1147 connector cable from the transceiver. It does not need to be grounded in any other way. The shielded cable must not be connected to the counterpoise or the radio ground or it induces a ground loop.
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Old 10-01-2011, 10:50   #12
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All I'm saying, is that the black wire in the control cable is the negative DC feed to the tuner and that it is connected internally to the RF ground stud, as is the shield of the coax feed. You previously stated, "The - on the tuner is NOT connected internally to the ground plane terminal ". That is incorrect, assuming that by "The - on the tuner" is refering to the negative DC feed. Either way, you cannot avoid possible ground loops in the coax shield and negative power feed as they are both connected internally to the RF ground stud.

Eric
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Old 10-01-2011, 11:05   #13
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Well if they are connected, then you have a problem. The manual clearly states that the RF ground should NOT be connected to the DC-. They are 2 distinct circuits. AVOID the following points, as these connections may cause noise or electrolysis:
Engine block
Ship’s DC battery ground
You will have a connection to the these DC- points if your radio RF ground is foiled, coppered, or connected any way to your ship's dive plate. You can avoid the ground loop by leaving the coax ground connected to the transceiver, but leaving it OFF the tuner as the tuner is grounded through the DC- feed through the OPC-1147.
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Old 10-01-2011, 11:49   #14
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Well if they are connected, then you have a problem. The manual clearly states that the RF ground should NOT be connected to the DC-.
The RF ground should not be connected externally to your DC ground, however it is connected internally in the tuner. That is not my "problem", that is the way Icom tuner's are built. The DC negative wire goes to the circuit board connection point. There are then two solid jumper wires in series that connect that point to the ground plane which is the same point electrically as where the RF ground stud connects to. Each of those jumpers has a small ferrite bead over them for RF suppression but there is still a direct DC path.

Quote:
. You can avoid the ground loop by leaving the coax ground connected to the transceiver, but leaving it OFF the tuner as the tuner is grounded through the DC- feed through the OPC-1147.
I have never heard of such a thing in all my 35 years as a service technician and installer.

Eric
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Old 10-01-2011, 12:53   #15
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Is the inverter and the tuner within 2 feet of each other?
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