Topband: Poor Conditions

[Jim Brown]

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