Topband
[Top] [All Lists]

Re: Topband: Input Impedance of the FT1000/S-Meter Calibration issues

To: "Richard Karlquist" <richard@karlquist.com>,"Tod - ID" <tao@skypoint.com>
Subject: Re: Topband: Input Impedance of the FT1000/S-Meter Calibration issues
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Wed, 11 Feb 2004 11:12:32 -0500
List-post: <mailto:topband@contesting.com>
> In fact, it can be shown that optimum noise figure NEVER
> coincides with a matched condition for bipolar transistors.

Not that I want to prolong this thread, but since we don't know what is
inside the receiver between the input amplifier and antenna jack none of
this means anything. Optimum noise figure might be with a near-perfect
match. It might also occur with significant mismatch to 50 ohms.

Everyone probably understands we have an essentially useless voltmeter (the
receiver) connected to antennas of varying sensitivity, I don't understand
why anyone cares if S9 is 30uV or 300uV.

The only important thing is knowing the rate of change over the scale range
so we can correct for scale errors.

We almost always want to know relative changes or differences, not absolute
values.

73 Tom


_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband

<Prev in Thread] Current Thread [Next in Thread>