The AWA Distortion aand Noise meter F240 Type 1A94766 is suitable for the measurement of total harmonic distortion, noise or hum-plus-noise in
audio frequency circuits. In conjunction with a suitable station monitor it may be used for overall performance tests of the audio frequency
characteristics of braodcast type transmissions.
Measurements are possible down to 0.003% . A manually adjusted (7 controls) parrallel T rejection circuit rejects the fundamental, leaving only
harmonics, hum and noise. A 400 Hz hi pass and 15 khz low pass filter are included as well as a 'programme weighting" filter.
In case any one else has one, here is the doco I have on the beast.....
Manual
Schematic
Block Diag
Characterstic curves
Measurement of CMRR and Return Loss
