[ARC5] Quick sensistivity comparison

[Kenneth G. Gordon]

RF gain max. AF gain low. Radio Shack CB speaker with 500:8 ohm transformer. Audio 
impedances are not properly matched, but there is still ample audio.

12SH7: AM 0.3 microvolt modulated 400 Hz at 30% clearly heard.
             CW 0.1 microvolt clearly heard.


12SK7: AM 1 microvolt, same conditions as above, heard mixed with noise
             CW 0.3 microvolt, heard, mixed with noise

Signal generator: HP-8640B fed to receiver through a 50 ohm terminator.

I must admit to being surprised.

Ken W7EKB