Here's one question I've been unable to figure out myself:
When was the first dual conversion shortwave receiver made, and which
model was that? The earliest model I could find so far via Google was a
1935 Tandberg Huldra 1B with a 2 MHz + 137 kHz config - not too bad for
a start (I hadn't expected to find something that old), but was there
anything yet earlier?

Stephan
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Meine Andere Seite: http://stephan.win31.de/
PC#6: i440BX, 2xP3-500E, 704 MiB, 18+80 GB, R9k AGP 64 MiB, 110W
This is a SCSI-inside, Legacy-plus, TCPA-free computer