OK Gang,
Tom got me going. The capacitor to bypass RF and "filter" the half wave
rectified DC to the meter can be 0.01 or 0.001, not really critical, as all
you are doing is having a reactance at least 0.1 the input Z of the meter.
Most digital meters are 10megohms, so most any cap will work as to value. Of
course, a disk ceramic is best for cheap RF bypass.
Now, what I did years ago that also works perfectly well for average QRO Field
Strength, is: took an old VOM I had, a WW2 version in all steel case, and on
its AC rectifier that was copper oxide bridge of two diodes, and burned out; I
substituted two 1N34 Germanium diodes. The AC cal was not affected enough to
bother because this was a handheld meter with 3 inch movement. The lowest AC
volts scale also works now for Field Strength when I stick a 2 foot wire (bus
wire or any solid wire), into the AC jack, and have it as a vertical whip.
The FS meter can be made of any junk box meter salvaged from the transistor
Short Wave radios of the 60's and 70's. You could even put all the components
on the back of the meter case and the bus wire whip and do away with need for
a case.
73, Stuart K5KVH
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