Re: [Amps] Re: 10dB and propagation

[David Kirkby <david.kirkby@onetel.net>]

Steven Cook wrote:

> Team,
>
> I have seen this many times myself -- however, I don't care nearly 
> enough to try and convenience anyone.  If this phenomena is merely the 
> result of S-meter calibration/response/accuracy, it is curious that 
> the error being reported is seemingly always on the high side. 

If a ham has a 100W transmitter and a 1kW linear, and switches in the 
linear in and out, it should make a 10dB difference.

If the person receiving the signal says it makes a 13dB (20x) 
difference, he will be happy to tell everyone about how good his linear is.

If he is told it makes a 7dB difference, he is far more likely to 
attribute the error  to the other persons deaf receiver, or badly 
calibrated S-meter. He is not very likely to go telling all his mates 
down the local club that his expensive 1kW linear makes only 7dB 
difference, which is what you would expect from a 500W linear.

So human nature could distort that, which explains why these effects are 
more often seen in one direction than the other.

> For some, seeing is enough.  For other, nothing will do. 

There are plenty of optical illusions. The moon often looks bigger when 
it is close to the horizon, but it is not actually any bigger or closer. 
Measure it *properly* and you will find out that is true. The earth-moon 
distance does change a bit during the month and year, but nothing like 
as much as the moon would appear to be bigger when its near the horizon.

It is not a case of 'nothing will do' but wanting to be thorough about 
something. Thinking about it. That is why it is clear to me any such 
amplifier discrepancies are far more likely to be reported when the 
linears appear to work better than expected, than when they work worst 
than expected.

> If Rich said it, that's enough. 

Exactly the sort of thing I would never do. Perhaps that is why I make 
my living as a scientist.

--
Dr. David Kirkby, 
G8WRB

Please check out http://www.g8wrb.org/ 
of if you live in Essex http://www.southminster-branch-line.org.uk/



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