Frequency response for SSB is easy to measure too. You will need a audio
generator capable of being adjusted to the proper output level, a meter to
read audio level in dB, a watt meter and a dummy load.
Feed a sine wave into the input. Be sure there is no clipping or overdrive
of the input or ALC or compression taking place. Use a watt meter and a
dummy load. Start at 400 Hz as a reference. Set the power to say 10 watts
by adjusting the audio level and note the audio level in dB. Change to 100
Hz and adjust the audio generator output level until you attain 10 watts
again. Note the level in dB. Do the same for as many frequencies as you
wish and note the level in dB as compared to 400 Hz level. Plot that curve
and invert it. Now you have the frequency response of the SSB system.
In the event you can't get 100 Hz through the system, and I doubt that you
can, then just move the audio frequency up until you see some output.
Works every time. You'll see the ripple across the top of the SSB filter
and the filter shape too. Most likely you will only be able to measure
response to a value of +/- 6 dB without getting into compression of an audio
stage within the radio.
73
Bob, K4TAX
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