Topband: Measuring field strength

[Dan Zimmerman N3OX]

> I'm afraid if we want to know the field strength change we
> just have to measure the field strength change. Nothing else
> works.
>
> It's all a gigantic waste of time and bandwidth if we don't
> measure what we actually want to know.

This is what I'm planning on doing when I return next week. I'm
thinking of doing the following, and I'm interested in comments.

I have a small CW transmitter (about 110mW)  that I can set up 1
wavelength away transmitting into, I suppose, a small loop antenna.
I'll terminate my RX in 50 ohms and could use a step attenuator to
measure changes in field strength.

I wonder though, if I'd get reasonable results with some fixed
attenuation and the AGC off on the RX, and just measure the audio
output with a soundcard audio voltmeter.

At any rate, it seems like I can do faster A/B testing of added
radials with a reciprocal method rather than having to key the station
transmitter and run out to the field strength meter each time.  Are
there any caveats to this method other than making sure that the RX is
terminated properly?

Dan