Travis,
The S-meter should not indicate anything with the antenna disconnected.
You should be searching for the reason the AGC is being activated on
receiver noise - or it could be S-meter calibration. The XG3 can allow
you to properly calibrate the S-meter - the Utility program will guide you.
73,
Don W3FPR
On 3/19/2013 8:34 PM, Travis Brown wrote:
Hi Don,
I agree 100%! The S-Meter isn't as big of a concern to me as the fact that
the noise floor seems to be so much more prevalent on the K3 than the KX3. I do
understand that the more sensitive receiver will dip deeper into the noise
floor and you will hear more of it. If I always have to turn down the RF gain
though, and the S-Meter shows something even when their is no antenna attached,
I think it is worth it to calibrate things. It's not like me to read manual,
but so far, I have a pretty good track record of reading everything Elecraft
sends me from cover to cover :)
73,
Travis K2NP
On Mar 19, 2013, at 8:12 PM, Don Wilhelm <[email protected]> wrote:
Travis,
The real measure of any receiver in the ability to hear weak signals is not in
the S-meter deflection. Within limits both the K3 and KX3 S-meters can be
calibrated to read most anything you want to see.
The measurement of actual sensitivity is in the MDS measurement. That indicates
how weak a signal can be heard at 3 dB above the receiver noise floor.
When you get your XG3, I encourage you to follow the instructions in the XG3
manual for determining the MDS of a receiver. With the XG3, that is a number
inferred by the response at -107 dBm rather than a measurement using a well
shielded signal generator and switching in attenuation, but the approximation
should be within 1 dB of the actual MDS if you do the procedure (and math) as
instructed.
73,
Don W3FPR
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