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[quote:172f57020d=”Clara-Listensprechen”]As far as “squeezing blood out of a turnip” for 114-odd miles, just below the 21 meter band isn’t a bad choice for QRP ops, really. Propagates best during the day and/or during summer for well over 114-odd miles, but in winter at night, not so much, but it may nonetheless do 114-odd miles handily, maybe. During daylight hours you can expect your signal to bounce off the ionosphere from here to timbucktoo and back. It’s a utility band, not a ham band, so it sounds do-able.[/quote:172f57020d]
That’s kind-of what I was thinking about its usability, based on the field strength levels (15848uV/m @ 30 meters, as opposed to 10000uV/m at 3 meters for 27 MHz and lower for some other bands (except 900MHz & above)) permitted.
And, based on Ramsey’s thing in their FM transmitter manual that field strength voltage drops off proportionately to distance, I calculated that if I had 15848uV/m at 30 meters, I’d have approx 2.6uV/m at 114 miles, which is probably a weak, but usable (for my purposes) signal.
How far would a usable 4.5kHz SSB AM signal go if its upper sideband went up to 9kHz, power output was 5kW, and the antenna was 1/16384 wavelength long? Also, at that low frequency, is that power level safe for near-field (within a few inches) human exposure?
And, about the 13.5MHz – where can I learn more about equipment used on that band?