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R: Re: SNR measurements



Hi Ron W8GUS,

Your suggestion to use the output transformer in the audio
circuit loaded as you describes is exactly what i do even using an old
DRAKE R-4C HF tube receiver with an additional  144-146 to
28-30 MHz additional conversion to take the advantages of
the AGC switching ON and OFF facility.

73" de i8CVS Domenico

----- Original Message -----
From: Ronald Long <rlong3@columbus.rr.com>
To: <amsat-bb@AMSAT.Org>
Sent: Wednesday, February 19, 2003 9:17 PM
Subject: [amsat-bb] Re: SNR measurements


> NX7U wrote:
> Once again, Domenico is right on the money--the key is a constant
bandwidth
> measurement that includes the noise in the bandwidth.
> ------------------------------------------
> One other possible source of error is the fact that the output impedance
of
> modern receivers is not constant or accurately known. An article I read
> suggested connecting an output transformer in reverse to the speaker
> terminals, say 8 ohms to a known value, R. Connect a 1W resistor of value
R
> across the R winding and connect the audio voltmeter across R.
>
> ron w8gus.
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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