The speakers used in the Pro-Micro are very sensitive and don’t require much AF gain from the transceiver. The frequency response is 20 Hz – 17 kHz with very low distortion. The ear pads are replaceable acoustic foam.
The Pro-Micro IC: contains the Heil IC electret microphone element. This element has been made to utilize bias power in ICOM radios which addresses low-gain issues that arise when using dynamic microphone elements. The -3 dB points are fixed at 80 Hz and 12.5 kHz. The IC element requires +5 volts DC bias power, which all ICOM rigs provide.
The use of the AD-1 series mic adapters allows simple interface with popular transceiver inputs. The adapter cable has a 1/8” female input jack for the boomset microphone and a 1/4” female that is for the PTT (push to talk) line for the Heil foot switch or hand switch. The 1/4” stereo plug goes into the headphone jack on the transceiver front panel.
To adjust the headset simply bend the stainless steel piece that is inside the black padded headband. All Heil Pro-Micro Boomsets are shipped with foam windscreen that fits over the microphone. The windscreen does not change the frequency response, just the breath blasts directly into the microphone.