Trying to teach myself electronics, I've been reading a few textbooks I
inherited on the subject. Tough going, as my math is in serious need of
repair.

Anyhow, found a couple of interesting things in these older books:

1. TRF:

In the section on modulation, demodulation and other radio-related stuff
one book brings up "the tuned radio-frequency receiver" before
discussing superhet, as one would expect. But they say;

During the evolution of radio, the tuned-radio-frequency (TRF)
receiver was used to receive AM signals. Today, a few special
applications still use TRF receivers.

Now, they go on to explain why TRF is inferior to superheterodyne. But
I'm curious: are there still any radios that use TRF? and why? (Keep in
mind this book was written in 1979).

2. Thermionic converters & magneto-hydrodynamic generators:

Another book (which I frankly don't like as much since it's so
math-heavy: wouldn't electronics be so easy to learn if all that goddamn
math didn't get in the way?) covers these somewhat fantastic devices in
its chapter on "Energy Conversion Phenomena". The thermionic converter
is especially intriguing, as it seems a fairly efficient (20%) direct
conversion from heat to electricity. I seem to remember seeing a program
on PBS about something like magnetohydrodynamics being developed for
deep-space exploration propulsion.

Are either of these devices being seriously researched or used nowadays?
Keep in mind that *this* book was written in 1966.


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.