Home / Radio / Fredbox: 2m AM Transceiver / Microphone Testing
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Loud whistle, about 10cm from microphone. Vertical scale is 1V/division, so the display shows 0 - 8V, measurement made at emitter of TR6. Supply voltage was about 8.3V.
Quiet whistle, about 10cm from microphone. Vertical scale is 1V/division, so the display shows 0 - 8V, measurement made at emitter of TR6. Supply voltage was about 8.3V.
Ordinary speech, about 10cm from microphone. Vertical scale is 1V/division, so the display shows 0 - 8V, measurement made at emitter of TR6. Supply voltage was about 8.3V.
Strange effect at the collector of TR4. After a loud whistle then silence, there is a slow and decaying oscillation of the voltage. Resting voltage is 1.0V when there is no sound. Width of this display is 2 seconds.