FCC Exam Question: 6A220
What microphones have a high impedance output?
Explanation: While some microphone types are inherently high impedance, others are not. However, in amateur radio, any microphone type can be made to present a high impedance output. Crystal microphones naturally have a very high output impedance. Dynamic microphones, on the other hand, typically have a low output impedance. However, a common practice in amateur radio, especially when interfacing modern low-impedance microphones with older equipment designed for high-impedance inputs (like many tube-type transceivers), is to use an impedance matching transformer or a preamplifier. These devices convert the microphone's native impedance to the desired high impedance, effectively allowing *any* microphone to "have" a high impedance output as presented to the radio.
6A612
6A374
6A362
6A300
6A175
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Includes Elements 1, 3, 6, 7R, 8, and 9.