On Wed, 11 Aug 2010 18:42:08 -0500, Stuart Rohre wrote:
You may
need to transform the audio to a higher voltage to improve your reception
Almost everything in this email is wrong.
See my tutorial on headphones in http://audiosystemsgroup.com/RFI-Ham.pdf
It's in an Appendix.
Most modern radios are designed to drive almost anything from 8 ohms up,
and are optimized for about 8 ohms to about 200 ohms. No matching required,
no matter how hight or how low the Z. With modern phones, the higher the
impedance, the less loudness you're likely to get from a modern output
stage.
On the other hand, the very old crystal headphones are very high impedance,
and also very sensitive -- 40 years ago I used them to do field service
troubleshooting on audio systems, and I could even hear (barely) mic level
with them! Fidelity was not great, comfort was even worse.
73, Jim Brown K9YC
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