Connunications update following Polls:

[Paul]

Most any superhet receivers transmit RF signal on receive but only a tiny tiny bit.

They have a little circuit in called a local oscillator.
In my old CB it ran 10.7 Mhz lower than the channel I was listening to. (or was it higher?)

Gives you an idea of what I'm talking about.

That signal is detectable and was what the old TV detector vans zeroed in on in Busby days (when naughty CBers were tracked down shot and stuffed as trophy's.)

Typical single DF accuracy of 30 feet over 100 yards.

It's also what some "RF bug sniffers" on scanners happily latch onto today.

Again close range unless you are using a really good handheld directional antenna but typically a maximum of 200 yards if there is absolutely nothing else on in the neighborhood.

My modern microprocessor based CB set is terrible at transmitting spurious RF signals though as does my PC.

It seems that the more modern the gear, the worse "noise" it generates.

That's modernization for you.

Gawd I love valves!