Geerling Engineering | This AM radio still costs thousands of dollars—why? @GeerlingEngineering | Uploaded June 2024 | Updated October 2024, 43 minutes ago.
My Dad put his Potomac FIM-21 Field Intensity Meter on the bench.

In 1986, this radio cost $1,950—which is nearly $6,000 today! (And this isn't even the most expensive AM radio today—there's a newer version for $15,000!)

It measures the field intensity of AM radio signals in volts, and a calibrated unit like this one can be used for official readings sent to the FCC for broadcast stations in the US.

A few other things we mentioned in this video (some links are affiliate links):

- Potomac FIM-21 Field Intensity Meter: pi-usa.com/legacy-products
- RTL-SDR v4 dongle: amzn.to/3KvDbku
- SaferCCTV AN-200 Indoor AM Loop Antenna: amzn.to/3KvDdZE
- Gqrx SDR software: https://www.gqrx.dk
- We made a hot dog talk... with RF: youtube.com/watch?v=GgDxXDV4_hc
- Workbench build video: youtube.com/watch?v=JV1Iv9bXkdI

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Merch: redshirtjeff.com
2nd Channel: youtube.com/@GeerlingEngineering
3rd Channel: youtube.com/@Level2Jeff

Contents:

00:00 - Field Intensity Meter 21
01:13 - Over 900!
02:22 - How to take a measurement
03:14 - Loop antennas, nulls, and SDR
05:56 - External antenna testing
08:16 - What about FM?
09:16 - Why it costs thousands of dollars
10:46 - Field Calibration
13:33 - Is it still useful?
14:46 - The importance of calibration
15:50 - Justifying the cost... with a hot dog?