You have to control the levels so that the transmitter doesn't get
driven into deviation limiting. Usually testing is done at 60% of system
deviation. I am assuming this is a land mobile transmitter? Connecting a
tone generator to the microphone terminals is best way to control the test.

chuck wrote:

In making FM transmitter distortion measurements, does anyone inject
the 1 kHz audio signal into an FM transmitter by holding the
microphone next to a speaker? It would seem that neither speaker nor
microphone would produce enough distortion of a single frequency to
affect the results, and in any case, the microphone is part of the
system being tested.

The idea would be to avoid having to fiddle with the variety of
microphone connectors out there.

I suppose I can and should compare the results of this technique with
applying the audio signal directly to the microphone input terminal.


Appreciate any thoughts. TIA.

Chuck
NT3G

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