I really enjoyed episode 171 and I wanted to share a few thoughts.
As a reminder, the way that radio communications work is that a traveling electromagnetic field passing through an antenna induces a small voltage in the antenna that is detected by the receiver.
In the case of an EMP, the traveling electromagnetic field is so powerful, and has such a wide bandwidth (being an impulse), that it induces a large voltage in all electronic devices and components that it passes through. If these induced voltages are weak enough, they might just disrupt the device enough that you need to reset it, but if they are strong enough, they can damage components within the device.
Another reason why we are more vulnerable to this now than we were 50 years ago is that our electronics have become more delicate. MOSFET transistors are more susceptible to damage than bi junction transistors are, and bi junction transistors are more susceptible to damage than vacuum tubes are. Relays, such as those used in telegraph lines, are the least susceptible to damage from a sudden brief voltage spike.
Therefore, your brand new radio with a computer inside is the most susceptible to an EMP, while your older solid state radio is a little bit less susceptible, your 70-year-old tube radio is much less susceptible (but may prove more difficult to power if the grid is down), and your hundred-year-old landline telegraph set is pretty much immune. Your spark gap transmitter and your cat whisker crystal receiver are also likely to still work after an EMP, though you may need to adjust the cat whisker.
Another Faraday cage that many people can use in a pinch if we happen to receive a warning about an impending event is their washing machine or dryer. Also, remember to protect all important electronics, including things like the charging controller for your solar cells and an extra battery charger and set of batteries.
I would also like to point out that there are some other low tech communication options that could prove very useful in a SHTF situation.
People who know Morse code can communicate up to a few miles using whistles, and whistles are essentially immune to damage from an EMP.
There are also visual signaling methods, such as the heliograph or the movement of flags or lanterns, combined with a set of binoculars, that could prove useful in such a situation. Many interesting details can be found in the 1910 “Manual of Visual Signaling of the US Signal Corps.” at https://archive.org/details/manualvisualsig01corpgoog
The curious reader may find the table of abbreviations on page 46 somewhat amusing, proving that “text speak,” including the use of the letter u for the word you, the letter r for the word are, and the letters ur for the word your, is not new.
Between the usefulness of whistles and visual signaling, I would submit that learning Morse code is an excellent investment for preppers.
Thank you again for your wonderful show,
PS I still think you should do a show on itinerant business band frequencies. See my email from Oct 14, 2021.