[TenTec] Headphones for ORION I?

[Jim Brown K9YC]

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