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*How many ohms is a typical vacuum tube hi-Z microphone? *How many ohms is a typical hi-Z microphone for old tube transceivers? *How about those microphones with the old crystal element, are they not "really" high impedance? *How about those microphones with the old crystal element, are they "really - really" high impedance? Impedance is the resistance to a non-DC current. It is the equivalence to resistance which a DC current and both are measured in ohms. Impedance is the resistance to a non-DC current. It is the equivalence to resistance with a DC current and both are measured in ohms. In an AC current we speak in terms of impedance rather than resistance. Impedance is more involved than DC resistance because it is actually the combined effect of capacitance, inductance, and resistance on a signal. Astatic D-104 microphones from back in the tube radio days is considered a high impedance microphone. An old D-104 with a crystal voice element checks in at around _4000 ohms_* which is considered pretty high impedance. Audio microphones in general are divided rather loosely into three classes of impedance.*Low ... 600 ohms or less*Medium ... above 600 ohms to 10K ohms*High ... above 10K ohms Astatic D-104 microphones from back in the tube radio days is considered a high impedance microphone. An old D-104 with a crystal voice element checks in over '''[http://www.internetwork.com/radio/kb1nfs/D104Matcher.htm 1M ohms]''' which is considered pretty high impedance. Later the D-104 went to an updated ceramic microphone element which remained high impedance. Over time there were changes in the ceramic element used in manufacture. When the amplified D-104 was introduced the impedance changed. If you desire using an old hi-Z microphone on a modern solid state transceiver then amplification is necessary. One approach is the use of a Field Effect Transistor. Later Astatic D-104 microphones were rated at _50K ohms_* impedance, still hi-Z but not as high.Turner produced many different microphone types over the years and specifically produced microphones for ham radio earlier in the company history. The Turner 254HC was produced by Turner for ham radio and is high impedance, or hi-Z, at _????_ ohms using a ???? microphone element. Later Turner produced many models of Citizen Band microphones including the model ??? desktop microphone which had a 9v battery under the base. This is a powered microphone which is considered low-Z at _600_* ohms.Turner produced many different microphone types over the years and specifically produced microphones for ham radio earlier in the company history. The [[Turner 254HC Microphone]] was produced by Turner for ham radio and is high impedance, or hi-Z, at _????_ ohms using a high output ceramic microphone element. Later Turner produced many models of Citizen Band microphones including the model ??? desktop microphone which had a 9v battery under the base. This is a powered microphone which is considered low-Z at _600_* ohms.Ohms resistance can be measured with a meter if you know the correct connector pins to use. If it is a powered microphone, such as one with a battery, you need to remove the battery to avoid damage to the ohm meter. ...more...Microphone impedance cannot be determined with an ohmmeter because the ohmmeter uses a very low DC current, where as impedance is the opposition to the follow of an AC current. You can use the ohmmeter to help determine what some of the microphone pins are for, such as which pair are for PTT, however, you cannot use to tell what impedance the microphone is rated. An impedance measurement would involve the use of a tone generator and oscilloscope and would not be exactly precise.Older high impedance microphones can be adapted for use on modern solid state amateur radio transceivers. ..more...Older high impedance microphones can be adapted for use on modern solid state amateur radio transceivers. ...more...==Related==* [[Dynamic and Condenser Microphones]]* [[Microphone and Line Input]]