Looking for a high impedance desk microphone for your vintage transceiver? Consider the Electro Voice 630 microphone. The EV 630 is a great sounding microphone for radio communications. The frequency response is 60Hz to 11000Hz. Output is a powerful 80 millivolts. Many high impedance microphone output about 50 millivolts. The frequency range has an approximate 2dB boost from 300Hz to 2kHz and another 2dB boost starting at 2.8kHz. This is great for clear & punchy audio with the low bass response. Some communications microphones have a frequency response from 300Hx to 6kHz that remove the bass. As for 6kHz, ham radios do not transmit higher than 6kHz AM and about 3kHz maximum on SSB. The Astatic D-104 is an example of a microphone with -2dB at 300Hz low response that removes the bass and a 10dB boost at 3kHz. Not a great sounding microphone for high quality transmitting frequency response. I find the EV 630 on eBay and with careful shopping are available for about $60. Look for the microphone large connector included as NOS costs about $35. For about $100 the desk stand with the microphone are available.