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Re: Topband: Poor Conditions

To: topband@contesting.com
Subject: Re: Topband: Poor Conditions
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Fri, 27 Oct 2023 16:12:51 -0700
List-post: <mailto:topband@contesting.com>
On 10/27/2023 3:09 PM, Roger Kennedy wrote:
But when I talk about Propagation being poor compared to over 20 years ago,
I'm talking about how much weaker signals have generally been on 160m.
Actual signal strength on a calibrated S Meter.

Hi Roger,

S-meters are calibrated to voltage at the antenna terminal of a receiver. Some have far better linearity than others. They do not measure signal strength, simply because their relationship to received field strength depends strongly on the efficiency of the receive antenna and it's directivity.

From where I sit, signals have not gotten weaker over 20 years, but noise has gotten 20 dB stronger. That trend is largely due to the proliferation of all sorts of electronics that are non-compliant with EMC regulations, including, but not limited to, switch-mode power supplies (SMPS), variable-speed motor controllers, battery charge regulators, DC-AC inverters for solar power systems. This trend is in addition to the periodicity of the solar cycle.

I don't know what it's like in the UK, but here in North America, the average home has several dozen such noise sources, mostly in the form of an SMPS for almost everything that plugs into the mains. And enforcement of EMC regulations is close to non-existent.

73, Jim K9YC


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