I read the story that told us "1 diode crystal radio can transmit AM RF signal if we talk to crystal earphone."
I tried to simulate to check if the story is correct or not.
The simulation outcome is in the negative.
See the following figures of outcome of LTspice simulation.
(1) When we talk to crystal earphone, RF/AM wave is not transmitted to antenna.
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Look at the "ANT" voltage. There is AF (audio frequency) that derived from crystal earphone but there is no RF wave on "ANT" terminal side.
(2) When we use RF signal of carrier 600KHz from outside (antenna)
We cannot modulate AM on the carrier 600KHz comes from outside (antenna).
Voice from crystal earphone as audio frequency does not ride on 600KHz.
Crystal earphone has very high sensitive performance.
It can sound audio signal even though it is very weak or very low voltage sound.
It also can be used as high sensitive performance microphone.
( But tone / audio characteristics is not always good.)
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