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I think there is a more sinister explanation. A more urgent one. You may need to have the power company ground and/or neutral repaired. A relative in Raleigh lived in a house that had that condition, and there were ~10 volts between the power ground and the shield of the coax going out to the coax dish. There was a spark when you hooked up the coax to the receiver which was plugged in and had a 3 wire power cord to it. I was over helping him hook up DirecTV. I told him that was dangerous and we chased it down. To make a long story short, the neutral lead to the house was bad, and the imbalance between the two 115v current draws was looking for any possible path back to the pole transformer neutral. The dish coax was grounded at the grass level to a new 8' ground rod where it went outside the building and thence up to the dish. That ground was the best ground in the house. Ultimately it was a fair expense to replace the power ground and ALL the neutral wiring from the main box to the pole pig. From what we could tell, the main path for satisfying the house neutral was via a green wire ground from the furnace to the gas pipeline. When the owner told the power company about the outside ground sparking to the outlet ground, they came out in a hurry. In your case, the tower ground may be playing the part of the best ground in the house. Be sure you don't have the problem above. 73, and hope that's NOT your problem. Guy. ----- Original Message ----- From: "Pete Smith" <n4zr@contesting.com> To: "Force 12 Reflector" <Force12Talk@qth.com> Sent: Sunday, July 28, 2002 9:12 PM Subject: Re: [Force 12 Talk] AC Voltage from Antenna > At 01:50 PM 7/28/02 -0700, Jim Smith wrote: > >between the shield and centre conductor, connect a low value resistor (100 > >ohms? 1 kohm? pretty arbitrary) between the shield and centre conductor > >and remeasure the voltage. I think you'll find that the measured voltage > >will now be very low, indicating that the impedance of the AC source is > >very high. If it were me and I found this to be the case I would go ahead > >and connect the radio, having removed the test resistor of course. > > > >Comments anyone? > > > >If you try this, let us know what you found. > > > Another approach would be to use a series capacitor in the center conductor > before your radio. My Heathkit remote antenna switch uses a pair of > paralleled .02 disc capacitors -- I'd guess 1 kv rating) to isolate the > relay switching voltage, which can be as high as 22 VAC, from the radios > and antennas being switched. > > > 73, Pete N4ZR > > Check out the World HF > Contest Station Database at > www.pvrc.org > > > > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > Force12 Web Site: http://www.force12inc.com > > To Submit Message to the List: Force12Talk@qth.com > To unsubscribe and view the Message Archive: see http://qth.com/force12/list > For problems with the list: contact n4zr@qth.com > > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact n4zr@qth.com |