[K3] Unexpected AGC versus RF gain behavior

[Cady, Fred]

I'm not sure I understand the following AGC versus RF Gain position
behavior. It may be the way it should work but it seems strange to me.

In a nutshell, the change in output audio voltage level, as measured by
the AFV and dBV measurement capability, is not what I expected for
different RF gain positions.

When the RF Gain control is fully clockwise (maximum), audio voltages
measured when AGC-F is on and AGC off are shown in Figure 1.  (See
https://sites.google.com/a/ke7x.com/www/home/miscellaneous-k3-informatio
n/unexpected-agc-behavior for figures.) Turning the AGC off results in
higher (louder) audio signal levels. What I expected.

When the RF Gain is reduced to about the 1 o'clock position (first dot
after 12 o'clock), turning AGC off results in lower (weaker) audio
signal levels until you get to about -50 dBm input signal level as shown
in Figure 2. Not what I expected.

In addition to this behavior, when turning the RF Gain through the 9
o'clock position there is a definite 10 dB change in audio level.



Fred Cady
KE7X
"The Elecraft K3: Design, Configuration, and Operation."
www.ke7x.com

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