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Another 2nd floor ground
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by VE3EQ on November 3, 2009
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Setting up on the second floor.
This is a modern house with grounded outlets and I am using a decent Triplitte power bar. However, all the equipment is older (TS940SAT/SM220/etc) and uses ungrounded 2 prong plugs. Thus, they are not electrically grounded by plugging them into the power bar.
Further I have a large Tuner that I think really should be grounded.
Is there a way to use the ground in the electrical outlets (as would be the case with modern equipment)?
Suggestions would be appreciated.
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RE: Another 2nd floor ground
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by K6LO on November 3, 2009
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My TS-940S has a three wire cable. For transformered equipment that does not, yes, you can ground it to the electrical panel ground via the center screw. Check first with a plug electrical socket tester to make sure your outlets are correctly wired.
RF ground is a different matter. If your antenna is located quite some distance from your shack you may not need one. This statement is near heresy to some, but it is true.
Should you find the need for an RF ground (fedback, rf bites, etc) you can try using some quarter wave wires from your equipment chassis or one of those MFJ "artificial" grounds.
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RE: Another 2nd floor ground
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by N3OX on November 3, 2009
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"RF ground is a different matter. If your antenna is located quite some distance from your shack you may not need one. This statement is near heresy to some, but it is true.
"
There is *no such thing* as an effective second floor RF ground. It's about as real as that unicorn currently operating from P5...
All there are are antennas of various forms, some of which are weird antennas that have lots of radiating "feedlines" and have parts lying around the shack floor or hanging down from the window (tuned radials).
If you have an "end fed" antenna and run a ground wire down from your shack station to earth, you're running an elevated feedpoint inverted L.
The fact of the matter is, and I would put it more strongly than K6LO, you NEVER need a station RF ground if you use the right antennas (self-contained ones like dipoles or ground plane verticals with good feedline chokes) or you use antennas that have their OWN RF ground.
Since you mention a tuner, you probably are going to use something like a ladder line fed antenna? If so, use a great balun on the back of the tuner and use a symmetrical antenna and you won't have any "RF in the second floor shack" trouble.
I personally use mostly coax fed antennas and would run all my coaxes downstairs and out near ground level where I had a ground panel with some ground rods (for lightning reasons) and out to the antennas, buried or on ground.
If I were running ladder line from an upstairs port, I would put a ground panel on the outside of the house with a heavy downconductor down to a bonded ground rod with something to ground the line when I wasn't using it and maybe some spark gaps. I'm not a big fan of protection by disconnect but I do recognize that people have different levels of acceptable risk, that lightning is rare, and also that running balanced line straight into the back of the tuner is easy and a nice way to build an antenna for a 2nd floor shack.
The shack RF ground is one of those things that hams swear by because by randomly changing things we may move a problematic common mode current maximum away from our radio desk and shove that standing wave peak down to another location. In the second floor shack case, fiddling with "RF grounding," radials on the floor, and "artificial grounds" will just increase the current somewhere on the system... and if you're real lucky it won't have a current maximum behind the TV downstairs on the other side of the wall :-)
If ALL you can run is an end fed wire fed against some mass of metal in your shack room, fine, do that. Better than being off the air.
But otherwise, just forget ENTIRELY about the impossible "Shack RF Ground" and use balanced or otherwise self-contained antennas and good chokes and baluns to *block* the currents that want to flow on the stuff in your shack.
73
Dan
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RE: Another 2nd floor ground
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by N3OX on November 3, 2009
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By the way, if you're concerned about your two-wire equipment for electrical safety ground reasons, the cleanest way to ground them is to replace their cords with three wire cords with the ground wire grounded to the chassis.
I'm a little confused in doing some research on your gear because the pictures of the TS-940 and SM-220 that I can find seem to use the very typical IEC power connector that's common on computers.
If this is true on your gear and the middle pin is connected to the chassis, just swapping cords to three wire computer type cords would do the trick for AC power grounding. Maybe the samples on line I'm looking at were destined for another market that more widely used grounded outlets when this gear was popular?
73
Dan
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RE: Another 2nd floor ground
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by WA3SKN on November 4, 2009
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OK, first reach for a voltmeter and verify the 3 wire outlet is indeed a correctly wired 3 wire outlet.
Then plug in the radio and measure for voltage between the chassis and ground. Then turn over the AC cord and again measure between chassis and ground. If you see a difference in potential, reach for the schematic to determine what is going on. If it is OK, you can then feel good about converting to a 3-wire connector.
And it is indeed a good idea to re-wire the eqpt.
For RF ground adding a simple radial to the tuner on each band planned should work OK.
73s.
-Mike.
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RE: Another 2nd floor ground
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by N3OX on November 4, 2009
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"http://www.w8ji.com/rfi_rf_grounding.htm "
I have an issue viewing this page in Firefox 3.5. Shutting off CSS by going to View -> Page Style and selecting No Style will work around this.
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RE: Another 2nd floor ground
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by AA4PB on November 4, 2009
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you can ground it to the electrical panel ground via the center screw
-------------------------------------------------------
Assuming that you are talking about the cover retaining screw, this used to be true but today many homes use plastic boxes with plastic covers and that screw is not connected to the grounding conductor.
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RE: Another 2nd floor ground
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by KJ4LCM on November 4, 2009
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Sorry to disagree, but that last answer is incorrect. ALL properly wired three wire recepticals have a grounded body. The box has no part in the safety grounding. The center screw is directly attached to the green ground screw on the receptical itself, and will go directly to the ground side of the panel. Of course, this is on a correctly wired system.
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