[ARC5] Quick sensistivity comparison

[Richard Hankins]

Ken,

you don't say what you were surprised by?   I am surprised that /any 
/valve HF receiver gives apparent sensitivities this low (either set), 
and would suspect leakage from your signal generator.

Either way, both sets of figures (if accurate) are academic. Aerial 
noise on the HF bands will swamp these figures by some 10 - 20 dB.


Richard G7RVI

On 13/06/2013 08:04, Kenneth G. Gordon wrote:
> 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
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