moamps
Well-known member
ruffrecords said:I have often wondered just how much distortion is introduced by the modulator itself in a 10,000W AM transmitter. FM is much less of a problem becuase it can be done at low level but an 10KW AM modulator is a whole different ball game.
The modulation in FM is done at few milliwats (at oscillator), the PLL is a most problematic part, but linearity of followed stages is also important. The overall THD can be below 0,2% (I measured it), but it also depends of receiver's quality and signal strength at receiving side.
THD on AM is not important at all . In early days for modulators are often used the same tubes as in transmitter part. The THD was about 10% IIRC at max modulation. A modern digital AM transmitters are better.