From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
Organization: Radio Society of Great Britain
To: rsgb_lf_group@blacksheep.org
Date: Thu, 1 Jul 1999 16:06:29 +0100
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Subject: Re: LF: field strength measurement again
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G3NYK wrote:
> To Mike yes I do use the steady signals of the 'beacons' for tests, but what
> does S9 mean?? Its a strong signal but is it 10uV/m or 1V/m. Most of the
> radios I have have S-meter sensitivity controls so you can set S9 at
> whatever you like!  I'd love to tell you by how much you have improved your
> system. 

OK, I agree this is very crude system, especially as some rigs, like 
my IC-706, have black squares representing each S-point or each 
'10dB' over 9. So there's no prospect of getting real numbers out of 
it - unless properly calibrated - but it can help as a very crude 
measure, especially as you know the signals you are checking are 
not only in the far field but have some sky-wave, too. There's no 
substitute for doing it right. Of course, a nice compromise is the 
Selective Level Measuring Set - when I think of the SLMSs and 
other test gear (capacitance bridge, 1Hz resolution VFOs, LF 
fundamental crystals) which I put in a skip when I worked for a 
telecom company a few years ago, it makes me cry!!

Thanks for the report on the main signal and the spacer.

> Just a thought as you are using a mixer source...have you tried keying one
> crystal oscillator? I find that quite clean and stable. It might be an easy
> mod.

Actually, I still use a straight Clapp VFO and a two-transistor 
Buffer/Keying stage. I like the two-crystal (XO +VXO) system but 
haven't got round to building one yet - have tended to concentrate 
on the size of the signal.


Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm