"Peter Bennett" wrote in message

are well into RF territory at 10 MHz, and will likely have to use
air-core coils in the tuned circuits.

Huh? Yes, he is well into RF and construction techniques will be different.
But while there are advantages to air-coil cores, their use in recievers
went out with hollow state detectors. Even in transmitters they tend to be
only used in the KW neighborhood anymore. I can't imagine that even in the
wilds of BC people are winding air coils and building on heavy steel
chassis.

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