LF: Field Strength Meter

[CHRISTOPHER OSBORN <c.cjo@btinternet.com>]

This bank holiday I finished PA0SE's field strength meter (LF Experimenter's Handbook) duly modified for 500 kc/s.

I knocked up Helmholtz coils of almost identical proportions to those in Dick's published design and with these calibrated the F/S meter.
Initial results look very promising and the meter seems quite linear up to my calibrated maximum of  6 mV/m.

This evening I trudged around the fields in Biggleswade making sundry readings, while my PC/TX  put out a test signal every 3 minutes.
If (?) my calculations are correct then I have an ERP of 40 mW averaged over 3 (1 km distant) readings.
I know this is not much of a sample but initial results are satisfactory and fairly consistent.

Apparently I am told that field strength measurement uncertainties are notoriously high - one RadCom informed letter suggests by as much as 6 dB.
If I wanted to be pedantic then presumably we should ensure that we measure no more than 25 mW ERP to
 allow for the worst case uncertainty (tongue in cheek!)

73 Chris G3XIZ

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