About 15 years ago, the Cable TV series "Mythbusters" took on the challenge of a radio that worked without a battery.CK-722 wrote: ↑Sat Jan 16, 2021 12:58 pmI measured the WJR field strength near where the 5 mV/m predicted contour approximately is in Flint. I measured it at about 3 mV/m.
In 48503, near where the CBD and Municipal Offices are located, V-Soft Zip Code shows 5.23 mV/m based on M-3.
In 48505, the North part of Flint, based on M-3 on V-Soft, WJR is 4.62 mV/m.
I'd say that WJR is more of a habit, but Cumulus no longer even subscribes to Neilsen there anyway. I'll tell you for a fact, that people inside the GM plants couldn't receive the 1968 World Series on WJR with most radios. With access to a window and a better transistor radio, it was still noisy. If a Flint AM like WFDF, WTRX, or WKMF had had the Tigers, it would have been easy. Better than 100 mV/m in the center of the 48503 area Days. WJR is easier in homes and in outlying areas.
I did an experiment probably 10 years ago with a radio inside a steel building in 48313. WUFL, with over 100 mV/m outside, predicted and measured with a real FI meter, was the only AM station that was listenable at all. WJR at about 22 mV/m outside was like struggling to hear DX. I was able to improve it slightly with about a 12" X 16" metal picture frame with much fiddling around, using it as a crude loop antenna. WWJ was next to impossible after the "upgrade", even with the loop.
It surprised me that they didn't know what a crystal radio was.
So, they ordered the product that was advertised and set to determine whether a radio that needed no battery, nor supplied power, could possibly work.
They firmly concluded: There's no way to make a radio that needs no power source!
They did the experiment at their site, inside a very large aircraft hangar, with the doors closed!
Made me suspicious of every other test they had done.