& Mark V







Elektret Condenser Mike Connections by DD9ZO

Problem: You cannot connect this microphone to the radio due to low-impedance (600 - 1200) input-terminal.

Solution: Here is a small addition-device to connect nearly all type of elektret-condenser-microphones to the rig. You do not need to open the FT1000MP. All you need is a resistor of 1200 Ohms, a electrolyt-condenser of 33 microfarad with about 10V Voltage and a 8-pin-microphon-plug. If you use small components you can put it inside the microphone-plug. It is easy to built because the FT1000MP has a positive-voltage-pin (+ 5V) already inside his microphone-socket.

Lets start it:

To pin 2 of the plug (+ 5V) solder a 1K2 resistor. The other end of this resistor solder to the positive terminal of a 33 Microfarad Electrolyte-capacitor. The negative side of this capacitor solder to pin 8 (Mike-In) of the plug. The connection between the resistor an the capacitor is now your new hot MIKE-IN-Point feeding the positive Voltage to the microphone-unit. Connect the electret-mike via a shielded-cable with this point and solder the shield to pin 7 of the plug an to the negative side of the microphone-unit. Also connect the PTT-switch to pin 6 and 5 of the plug.

To prevent of ground-loops never connect pin 5 an 7 together!

That is the whole work. You can use all types of electret-microphones, even a amplified electred-mike like a SM2 from ICOM can be used. Cheap headsets from the computer-industries works also with this connection.
Here on my side I am using a SM2 Desk mike and alternately a small elektret-mike from a wireless-telephone built in a HEIL-Headset. The original HC4 Microphone from HEIL works on a FT1000MP like Mickey-Mouse in a can due to wrong microphone-impedance (about 3K) of the HC4.

The FT1000MP Menue-point 4.4 (TX-AUDIO-EDSP) is switched to off. I often get a ...excellent-audio... report from other stations. Even with the ...German-legal-power... from a pa-stage and the dipole-antenna only 10 meter away from the shack, I never had RF-feedback in the mike-line.

With the monitor-function on the rig, a headphone on your ears, and a dummy load on the output you can easily test all kinds of microphones also using the menu-settings 4.4, 5.9, 7.7, and 8.9 to create a good audio signal for your transmission.


I am not responsible for malfunction of your equipment after doing this modification. No warranty of function for this addition-device. Guenter DD9ZO





This site was last updated 08/27/07