[Radio Wrangler]

We're stuck with the speed of light, or so it seems, so all signal connections and cables introduce delay. So all lines are delay lines. The ones thus named are just the ones where the delay is the wanted function.

You can make pulses timed by resistor/capacitor or resistor/inductor, but using a length of cable as a delay element is rather elegant, and can be made very stable.

You can simulate the cable with a large array of inductors and capacitors (as in Les' marconi scope) but real cable can give better bandwidth and better phase linearity.

For FM tuners where cost is an issue, the ratio detector seems to be the demodulator of choice. A pulse count demodulator has a much higher parts count unless corners are cut and then the advantage over the ratio detector is lost.

For a matter of teaching the operation of a circuit, it's best to avoid cut-down versions where the boundaries between circuit functions have been made unclear as parts have been saved.

It may sound counter-intuitive, but the one with the most parts can be the clearest to understand.

David