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Re: [TowerTalk] Shack wiring

To: "Tom Rauch" <>,
Subject: Re: [TowerTalk] Shack wiring
From: Pete Smith <>
Date: Mon, 24 Jan 2005 11:28:03 -0500
List-post: <>
At 11:07 AM 1/24/2005, W8JI wrote:
So you need two meters need to measure the true
peak and you need to measure the true RMS. Capacitor input
supplies run off the peak, and are more sensitive to line
ESR at a  given power load than resistive loads like choke
input supplies or filaments.

Thanks to Tom and everyone else who wrote. Yes, Tom's right about 110 vs 120 -- somewhere 50 years or so ago I formed the mental habit of calling it "110." That was appropriate at the time, I think. I'm told the current ANSI spec is 120/240 +/- 5 percent.

Not having either a true RMS and true peak meter, I intend to follow the advice of some others and verify that the two legs of the service are within a volt or two of each other at the panel, and let the power company put a recording voltmeter on the service to see if the problem is there. Frankly, I'm betting on that, because our power company is in Chapter 11 and the county's population is growing fast. I'm only a couple of miles from the substation, but it's one that serves a lot of the population growth. The extreme lows I've noticed are all relatively early in the morning, which suggests a peak load for heat pumps, lighting, etc.

I just measured a 110 outlet close to the panel and the voltage was 111.1 Upstairs, about 60 feet of wire away, with the two radios on receive, I measured 110.1. Turning off all the "radio" side (radios, rotator and stack controllers, etc.) it went up to 110.8. Just now it hit 111.7 in the shack for a moment -- now 110.2. Lots of fluctuation. I don't know if these are either RMS or peak voltages (most likely some fudged version, because it's not a Fluke).

Assuming the wiring is #14, my Handbook says the resistance is .252 ohms per 100 feet. Measuring at an outlet in the shack, equipment in the shack is drawing through ~120 feet of that wire, right? That doesn't sound wildly off to me.

Or have I misunderstood something fundamental? Wouldn't be the first time.

73, Pete


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