K=D8HB wrote:
wrote

No because the project emphasizes AM, an old spectrum-hog
mode which ought to have been retired about 1965.

Why? AM is a legal mode, with advantages and disadvantages.

AM is a relic, inefficient in it's use of spectrum, and
inefficient in it's use
of power (only half of the transmitted power contains
intelligence and half of
that half is discarded at the receiver!).

Actually, in an AM signal (full carrier modulated 100%) only 1/3 of the
power is in the sidebands. The other 2/3 is in the carrier.

In an AM receiver designed for the mode, all of the received sideband
power is used - none of it is discarded.

OTOH, the PEP of an AM signal is four times the carrier power.

By comparison, two SSB signals can easily fit in the spectrum used by
one AM signal. With no carrier heterodyne squealing.

OTOH, ten PSK31 or Morse Code signals can easily fit in the spectrum
used by one SSB signal. So who is the spectrum hog?

One of the key elements of the spirit of experimentation in
something "different" is not being constrained by what is
considered electropolitically correct.

I don't know WTF the phrase "electropolitically correct"
is even supposed to mean.

It's a term I invented. It's political correctness applied to
technology.

Here's an example:

"AM is a relic, inefficient in its use of spectrum, and
inefficient in its use of power"

Besides, the Class E technology can be adapted to
a variety of modes.

Yes, it certainly can. Which makes it all the more
puzzling that they'd
showcase it with a doddering old mode like AM.

Does old mean bad?

PROFESSIONALS still use AM, btw. To some people, if something is used
by PROFESSIONALS, it's electropolitically correct.

Class E is technologically
interesting, and kind of "electro-sexy".

Why? For me, one of the attractions is that you can't just run out and
buy it.

Showcasing it in an "AM suit" is
equivalent to showcasing Jessica Simpson in a fully secured
HAZMAT suit.

Class E can't do SSB - it's not linear. Nor can it do PSK31 for the
same reason, although it might be adaptable with a modulator.

Incidentally, the technology is a little older than Jessica.

I prefer classier types.

See "Class-E, A
New Class of High-Efficiency Tuned, Single-Ended Switching
Power Amplifiers",
IEEE Journal of Solid State Circuits, Vol SC-10, June 1975, pp. 168-=
175.

Yup. But a theoretical paper is one thing, and a practical project
that's on-the-air is something else.

And there's a reason for the AM emphasis.

One of the advantages of AM is its extreme simplicity. Remember rigs
with simple screen modulators, or the classic "Simplest Modulator" that
plugged into the key jack of a cathode-keyed Morse Code transmitter?

One of the disadvantages of AM is the difficulty and expense of high
power. Remember 500 watt modulation transformers and all the trimmings
needed to run legal-limit AM back in the days of "1000 watts plate
input"?

High power AM for hams was so expensive that only a few legal-limit AM
rigs were ever built for hams. I know of only two - the Collins KW-1
and the EF Johnson Desk Kilowatt. Both were in the "if you have to ask
you can't afford them" price range. There was also the size and weight
situation. 6 foot rack weighing hundreds of pounds was 'compact'.

So it was a natural for hams to homebrew AM rigs and keep looking for
that magic idea which would make high power AM more affordable and
compact.

With SSB, the complexity is all in the small lowlevel stuff. How many
hams would homebrew an SSB transceiver?

But high power SSB could be done in a desktop box like the SB-220. At
first enterprising hams built their own, but that became increasingly
rare.

The SSB transceiver and the grounded-grid Class B linear amplifier did
as much to kill off homebrewing and tinkering
as any other factor.

73 de Jim, N2EY