Howdy,
Could I build a little crystal set like I did as kid to use as a field strength meter?
Relative-reading field-strength meters using a 1N34A germanium diode and a microammeter have been used for many years. They don't actually measure field strength, and they are very nonlinear because of the nonlinear response of the crystal diode. A short whip acts as a pickup antenna. A small increase in field strength can cause a big increase in reading because the indication follows something like the "square law." They are useful for adjusting a transmitter for a peak radiated RF output from the antenna.
these meters would have to be brought close to the antenna when testing a Part 15 AM transmitter because they are not very sensitive.
I've used a standard CB field strength meter with a long piece of wire. It's not accurate but it's good for peaking both, the Rangemaster or the SSTran, or any Part-15 AM xmtr.
