[Patrick Turner]

Eeyore wrote:

Bret Ludwig wrote:

Eeyore wrote:
Bret Ludwig wrote:
Stuart Krivis wrote:
On 25 Sep 2006 12:51:12 -0700, "Bret Ludwig"
wrote:

Triodes are cheaper to build than beam power tubes of a given size,
simpler, and can be used for amplifiers of any size. Most 50 kW AM
broadcast transmitters had two triodes in their modulators giving 30 kW
audio power in Class B.

AM transmitters are a bit orthogonal to the topic at hand. :-)

Don't MAKE me get Allison on you! Every one had a BIG AUDIO AMP. Else
you would have had nothing but Morse code.

And since when was AM 'hi-fi' ?

That would be before VHF FM became dominant. On days with little
electrical storm activity in the hemisphere and in the right locations
very fine broadcast fidelity was possible. Even today, at a place I
visited in north central Missouri I heard KXTR from Kansas City through
a passive Millen tuner (essentially a crystal radio) in astonishing
fidelity at an elderly hi-fi buff's house. Shame everything they play
is by the appalling Sir Neville Marriner at the Academy of
St-Martin-in-the-Fields. Vintage Toscanini and other classic
conductors' recordings would be so much better, but instead they play
that LOAD continually.

They say LF transmissions in England and Germany were even more
impressive.

The problem with AM AUIU was always one of bandwidth for one part and of course
that any interference was directly demodulated.

Those old valve sets did sound rather good though ( I had one myself - an EKCO !
) but that for the most part was mainly due to the excellent design of the RF
circuitry.

Graham

Most AM tube radios were built down to a price rather than up to a quality.

Most are just examples of poor performing junk.

Worse are 95% of SS radios.

But AM could have been wonderful but having many stations spaced at
9kHz apart thus limiting the AF bw due to side band interference was more
important than ****ing fidelity.

One would require 40kHz of RF bw for 20kHz of AF bw, so there would be much fewer
AM stations on the band if this had been used for the standard.

With FM, the problems were reduced, but even then they settled for second rate specs
of only 15kHz of bw for audio, pilot at 19kHz and a subcarrier F for stereo at 38kHz
when it should
have been at 100kHz, thus allowing the pilot tone to be at say 25kHz.

Now we are supposed to be getting better when digital broadcasting gets started
but I never see exactly what the specs are for that...

Patrick Turner.