EMS helicopter, XPR 6550 installed and tied into our audio systems so we can use it as a radio with our helmets. Has worked for years however the audio quality has always been poor, my guess is the portable radio's built in microphone or a lapel mic/speaker setup is not matched well with our helmets microphones. They came with PMMN4024A mic/speakers and I tried to take one apart and try to either measure or find a part number for the microphone to gather info, got nothing.
Helmets are Gentex SPH-5 with 5060-4 microphones. Here are the specs on it.
SENSITIVITY @1 KHZ: -28 dBV/Pa +/- 3 dB
Frequency response: 100 Hz to 10 KHz
Distortion: Less than 3% THD @ 120 dB SPL across
specified frequency response
Impedance: Less than 50 Ohms
Rated load resistance: RL : 100 to 1800 Ohms
Rated supply voltage: 8 to 30 VDC (not polarity sensitive)
Rated Current drain: 40 mA max, Ta = 25oC
Any thoughts on how to match or what the problem would be?
Helmets are Gentex SPH-5 with 5060-4 microphones. Here are the specs on it.
SENSITIVITY @1 KHZ: -28 dBV/Pa +/- 3 dB
Frequency response: 100 Hz to 10 KHz
Distortion: Less than 3% THD @ 120 dB SPL across
specified frequency response
Impedance: Less than 50 Ohms
Rated load resistance: RL : 100 to 1800 Ohms
Rated supply voltage: 8 to 30 VDC (not polarity sensitive)
Rated Current drain: 40 mA max, Ta = 25oC
Any thoughts on how to match or what the problem would be?