[Patrick Turner]

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' ?

Graham

The best transmissions here have 9kHz of audio modulation.

In 1999 I built a tubed AM radio with a flat AF bw of 10Hz to 10kHz, which meant
the
IFT had to be carefully contructed for a wide pass band of about 17kHz,
and some treble boosting compensates for the sideband cutting.

So although 10khz is missing from the 20kHz of AF bw needed for true hi-fi, my
AM
radio is unsurpassable compared to all other AM radios I have ever worked on.
All brand name AM tuners and radios have less AF bw than my set because they
were
designed to give about 7kHz max of IF bw so AF is restricted to 3.5kHz if one is
very lucky
and with many SS AM sets the AF is about 2kHz, and the distortion is much
higher.

The audio amp in the radio is an EL34 in triode with 12AX7 driver and with 12 dB
of NFB.
There is a full range two way speaker in a floor standing reflex box under the
radio set.
The radio provides truly wonderful, musical, undistorted and non tiring
listening.

Patrick Turner.