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PPM3 Page 21
TESTING YOUR PPM3
Now it’s time to see all your hard work pay off. Here’s what you’ll need to
test and use your PPM3
• An 8 to 15 volt DC power supply, positive tip
• CD player or other device to provide a line level audio input to the PPM3
• A stereo or other device that has line level inputs
• A microphone
• A telephone with phone line attached
• A length of standard phone line cable
• An RCA cable to connect your line level audio source to the PPM3
• An RCA cable to connect the output of the PPM3 to your stereo or other
line level device for testing and eventually for connecting to your
transmitter.
We assume that you’ve carefully checked over your construction before
connecting power and energizing the circuit. Yes, we warned you! If you run
into problems at any point, move straight to the troubleshooting section.
1. Turn all volume pots (R12, R2, and R15) to minimum
(counterclockwise)
2. Connect your 8 to 15 volt DC power source to J4
3. Turn on your PPM3; the green power LED should light
4. Connect your RCA cable from the line level source to the dual RCA
jack labeled “Input” on the back of the PPM3
5. Connect your RCA cable from the dual RCA labeled “Output” on the
PPM3 to your stereo or other audio device with a line level input. This will
be used to test the audio section of the PPM3. Later you’ll disconnect the
stereo and use the output from the PPM3 as the line level stereo audio
source for your transmitter.
6. Make sure your line level audio source is operating and you have a
suitable level of audio going to the PPM3. With the PPM3 turned on and
the volume on the stereo at a comfortable listening level, slowly turn R2
clockwise to increase the volume on the PPM3 until you can hear the
audio coming through. You should be able to vary the audio level with R2
and also see the “Clip” LED light with peaks in the music.
7. Next connect your microphone to the “Microphone Input” on the
PPM3. Now push the “Mic” button; the red LED should light. Speak into
the microphone and vary the volume using the “Mic Volume” knob.