[Elecraft] S-Meter Calibration

[Don Wilhelm]

Tom,

Yes, the AGC does have a direct relationship with the S-meter.  In fact, the
the circuit to drive the S-meter is the same as the one that produces the
AGC voltage.  So really, the S-meter is nothing more than an indication of
the level of the AGC voltage.

In the newer K2's there are 3 things that will contribute to the
'stingyness' or livelihood of the S-meter.  The AGC Threshold pot on the
control board (R1), the S HI and the S LO settings in the menu.  Set the AGC
Threshold first.  The older models do not have the threshold adjustment, but
it may be added by manipulating the value of R1 on the control board, but it
is a fixed resistor instead of a pot.

When setting the AGC Threshold, the 3.8 volts mentioned in the manual is
correct for most K2s, but you can refine that adjustment if you prefer.
Listen to a quiet band and then turn the AGC off  (hold and release the
PRE/ATT and the AGC buttons at the same time).  If there is an increase in
the band noise level when the AGC is off, the AGC Threshold is not correct -
set the voltage to something a bit lower and listen to the AGC On/Off noise
levels again.  Check all bands this way - if the noise level increases when
switching the AGC Off, that indicates that the AGC circuit is holding the
receiver gain down even with no signals present, and it should not do that.
As the manual says, if one changes the AGC threshold adjustment, you must
re-do the S LO and S HI adjustments (adjust S LO first, the other way 'round
may cause incorrect readings too).

73,
Don W3FPR


----- Original Message -----
>
> The S-Meter on my K2 (s/n 1103) seems to not be very sensitive.  When I
> receive, what I perceive to be very strong signals, I am only getting
about
> two or three of the LED's lit.  I've calibrated the SLO and SHI (I think
> that is the setting on the menu) several times yet I'm still getting the
> same results.
>
> Perhaps I am not setting some  of the other setting properly...the only
> thing that I am doing is making sure the RF gain is full clockwise.
Should
> I also be concerned with some of the other setting (I usually don't have
the
> "atten" on) - how about the AGC, does that have any effect?
>