Re: Microphone appears dead


Arv Evans
 

Several ways to test your electret microphone capsule.

1)  make up a simple adapter so you can connect its output 
to the audio  input of the receive side of your transceiver.

2)  Wire up an LM386 as a simple audio amplifier and connect 
the microphone output to this amplifier input.

3)  Wire up a microphone bias circuit and measure the mike 
output with an oscilloscope.  Level should be around 45 to 50 
millivolts.

4) try your microphone on some other rig.

5) Wire up a microphone bias circuit and connect the microphone 
output to a pair of sensitive headphones.

6)  Use an external audio amplifier with input capacitive coupling 
and listen to audio from the microphone amplifier in your BITX.
This may be distorted due to mixer effects.

7)  Wire up a microphone bias circuit and use it to connect your 
microphone to a record player input.

8)  Wire up a microphone bias circuit and use it to connect your 
microphone to the audio input of a VCR or TV.

9)  Wire up a microphone bias circuit and use it to connect your 
microphone to an amplified computer speaker.

When building the microphone bias circuit it could be helpful to 
include connection to the PTT switch through an LED and current 
limiting resistor so you can test PTT operation at the same time.

Arv
_._

On Sat, Jun 27, 2020 at 9:58 AM thomas.adair <thomas.adair@...> wrote:
How can I test my microphone to see if it is working? The radio receives well, but I not connect to anyone. With my digital voltmeter I unscrewed the jack, place the negative lead to the negative side of the jack and probed the center with the positive lead and actuated the PTT. 0 mV was the result.  

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