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Author Topic: Grounding on the second floor  (Read 204 times)
KB5QPN
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Posts: 9




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« on: February 23, 2003, 08:19:49 AM »

I recently moved my TS-830S to a second story location and do not have access to ground.  Is there a way that I can construct an "artificial ground" that will work?
Thanks,
Don KB5QPN
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AC5E
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Posts: 3585




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« Reply #1 on: February 23, 2003, 08:40:49 AM »

HI Don: There are several sorts of ground. The first is the "safety ground," which SHOULD be taken care of by the grounded "pin" connnection on your wall sockets. But it's been my experience that relatively few of those things are actually grounded. And it's also been my experience that a safety ground is not absolutely necessary for second story ham shacks because there's no way you can contact your rig and something that's grounded. So you can't become part of the ground circuit.

On the other hand, RF in the shack can be a serious problem. If your mike is biting your nose when you transmit or your audio is distorted you have an RF problem. The usual cause is a mismatch at the antenna feedpoint. The outside of the coax makes a better match to the coax than the antenna so most of the RF comes back down the outside of the shield. And what's not radiated causes trouble in the shack.

A "counterpoise," essentially a quarter wave antenna attached to the rig may radiate enough RF to reduce or eliminate the problem. That's the theory behind the "artificial grounds," avilable from MFJ and others. But that's also a bandaid solution.

The most effective cure for RF in the shack starts at the antenna. A better match where you operate is a start. Adding enough coax to make your feedline an even number of half waves long where you operate will make your coax shield "high impedance" and reduce the amount of RF on the outside of the shield. A "current balun" (see www.radioworks.com for more info) at the antenna feedpoint can choke off unwanted RF and improve your antenna's efficency.

Running the coax through a lightning arrestor mounted on a ground rod, at ground level, with a current balun on the shack side of the arrestor will often cut RF in the shack to an unmeasurable level. A few ground radials on the ground rod will help. Another current balun between the rig/tuner and the coax will further reduce the amount of RF in the shack.

Other solutions are possible, but these should give you a start.

73  Pete Allen  AC5E
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N8PZD
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Posts: 42




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« Reply #2 on: February 24, 2003, 08:25:32 AM »

Working as an electrician I see this problem often, using an electrical tester to determine the electrical ground was secure where the electrical power outlet is located. This has little if anything to do with RF grounding and should not be used as a RF ground, for power supplies yes, radio no. What happens is you are using the internal house wiring as your counterpoise, in the absence of a RF ground the stray RF travels along the internal wiring back to the electrical load center and may well continue out where ever if decides to go, dishwasher controls, clock radio, television set. I am mostly called into these scenarios when the home security system goes wacko and sends false alarms, fire or CO signal out to the station.
How to fix - get a RF ground to the coax switch, transmitter or antenna base, this will be a 8 ft 5/8 ground rod driven below grade or the soil line, most installations of this rod are 24 inches away from the foundation to prevent rupturing the foundation drain pipes, connect green covered or bare wire at least 12awg to your station components, this can be buried till you reach the cement wall and looks nice if secured with grommets - seal the insects out where you go into the house. This wire should be continuous to the station area, no splices - none are permitted per NEC - however obstacles arise and variances are determined on a case by case study by the authority having jurisdiction in your area. Some home improvement stores that stock electrical panels also have the grounding bars that can be fitted into the older 14 inch wide panels that weren't originally equipped for grounding, these make nice station connect points if you mount this underneath your operating table you can run short wires to your components easily. If the RFI persists once you have your station ground secure then you are flooding something with near field radiation and will have to solve that one device at a time with ferrite beads or covering the openings on appliances with grounded tin foil and probably then follow with aluminum window screen segments as a more permanent solution.

 Hailing from NOARS Country,
 73...Clark Beckman N8PZD
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N8EKT
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Posts: 371




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« Reply #3 on: February 26, 2003, 03:11:23 PM »

Being an engineer, I won't advise you eliminate any electrical safety grounds for any reason!
This may get you killed!
R.F. grounding however needs to be as low impedance as
possible.
you should have as short and straight as possible a heavy ground conductor run from your equipment to a ground rod "system" consisting of multiple rods.
Grounds are not to be taken likely!
Should the transformer in your rig or a bypass capacitor short, 120volts may be present on the case of the equipment!
If you isolate or remove this third prong you or a loved one may be killed!
Consult the National Electrical Code for further.
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