Grant Youngman wrote:
> Take a look at what happens to THD at a passband shift of 2000 Hz or over
Part Four - THD & IM with PBT offset
====================================
Sub RX, V2.056, 900 kHz, AM
BW 6000 Hz, PBT = 2000 Hz
HANG 0.3 seconds, 5 dB/s
measured at speaker output with external 4 Ohm speaker connected
Total Harmonic Distortion
modulation frequency = 1100 Hz
mod. depth THD
------------------
10 % 7.5 %
20 % 4.7 %
30 % 4.9 %
40 % 6.0 %
50 % 7.2 %
60 % 8.6 %
70 % 10.1 %
80 % 11.5 %
90 % 13.0 %
100 % 14.5 %
Intermodulation
modulation frequencies 1400 and 1500 Hz
peak modulation depth 80 %
The level of 100 Hz intermodulation product
is -18.8 dB below single tone, i.e. 11.5 %.
73,
Sinisa YT1NT, VE3EA
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