[Elecraft] K3 / RF gain - S meter issue - Similar issue

[Don Wilhelm]

Al,

My understanding of the hardware AGC is that it is fixed and is not 
dependent on the menu AGC parameters.  The AGC THR and SLP are strictly 
DSP parameters.

The Hardware AGC is there only to protect the ADC from overload due to 
strong signals.

There may some variation in the exact level that the Hardware AGC kicks 
in form K3 to K3 due to component tolerances.

The fact that the manual RF gain operates at the Hardware AGC point may 
be sufficient explanation that the RF Gain Control when at full 
counterclockwise position does not drive the S-meter to full scale 
(again due to component tolerances).

The real question in my mind is whether the K3 S-meter responds properly 
at its calibration points of S-9 and S-9+30.  And those points are 
correct with the RF Gain at full clockwise rotation.  Those calibration 
points are determined in the DSP section, and not in the hardware part 
of the K3.

73,
Don W3FPR

On 12/14/2017 6:40 PM, Al Lorona wrote:
> This would be easy to test. Normally, 'hardware AGC' kicks in at an input signal level of -46 dBm or so. This point is essentially independent of the AGC THR and SLP settings. See if your K3 varies from this data point anomalously.