[Elecraft] K3 Roofing Filter Gain Setup

[Lyle Johnson]

RF Gain Calibration  measures the effect of the hardware AGC voltage on 
the K3's receive gain, in dB.

It uses a narrow filter setting to improve the S/N of the signal 
measured by the DSP as the gain decreases and the signal being measured 
is reduced in amplitude due to that decrease.

The hardware AGC voltage is applied after the 8.215 MHz roofing filters, 
so the accuracy of the filter gain compensation is of no practical 
consequence as long as the roofing filter selection is not changed 
during the calibration process.

Becasue the hardware AGC calibration may affect the reported S Meter 
values, S Meter calbration should be checked and adjusted if required, 
after RF Gain Calibration is completed.

73,

Lyle KK7P

> I wish somebody would explain excatly what the RF gain calibration does
> and how it works. This is typically done after the crystal filter gains
> are set.  The procedure asks one to set the filter width to 100 Hz.
> That of course would kick in the 200 Hz filter here.  But some have said
> this procedure sets the gain of the stage before the filters.  So why
> specify a filter width setting?  What is monitored during the RF gain
> adjustment process?