In article 0,
says...


"Steven P. McNicoll"
It's referring to "whistle stop tuning", introduced by NARCO, I
believe, in the late forties or early fifties. Back then you'd
transmit on one of four(?) crystal-selected frequencies but select the
receiver frequency on a tuner that covered both nav and voice bands.
Activating "whistle-stop tuning" turned the transmitter on at very low
power, when the tuner reached the transmitter frequency you heard a
whistle and knew you were on the right frequency.

Steven, I thought that the heterodyne whistle "stopped" when tuned to
the exact frequency. Been a long time ago though.

Bob Moore



Great! Thanks for that piece of information. With that I was able to look
it up and find a wealth of information on the subject.

Sounds right to me that the whistle would "start" and not stop at the
right frequency, because that's where you'd get the feedback tone. Not to
be confused, of course, with the four-course range approach, where the
tone would become steady on the correct course.

The Motorola, by the way, unit does boast 180 transmit and 280 receive
channels at 100MHz (double those for the upcoming 50MHz), though they
indicate 122.1 is the "primary" enroute communications channel. Not
exactly 8.33 spacing, but now that we've bettered the "whistle-stop" the
path is direct to what we know today.

The unit featured "all-transistor power supply" and partially
transistorized transceiver, with only the power supply requiring remote
mounting... 9 pounds total.