[Elecraft] K3 Main RF Gain problem

[Jim Byers]

On 09-12-23 0:59 , Wes Stewart wrote:

Wes

RF Gain calibration completed as per manual no problems seen in the 
calibration procedure.

If in Config menu >>Smeter OF or other Smeters menus and I move the RF 
Gain the Smeter will respond as you would expect.(this is just a curious 
sidebar that is probably not useful info)

In normal operation AGC OFF or ON S or F , PRE ON or OFF, ATT IN or OUT, 
ALL MODES ALL FITERS   I get a gain increase in the main rcvr at the 
9:30 position of the the main rf gain.

Since the RF Gain calibration works for the sub reciever and the RF gain 
and S meter on the Sub rcvr  work correctly I am beginning to suspect 
the JFET  IF Amp and associated circuits of the main rcvr.

Jim

> Jim,
>
> You say that when you do the S-meter calibration the gain control 
> operates as you expect, but is somehow different otherwise.
>
> First, I hope you mean the rf gain calibration, which isn't 
> calibrating the S-meter but trying to compensate the ill-defined gain 
> v. volts curve of the JFET i-f amplifier.
>
> Nevertheless, after doing this, what are you changing that makes the 
> difference?  Is the AGC is the same state, i.e. on or off both ways?
>
> Wes
>
>
>
>     Hi
>
>     Looking for some insight.
>
>     K3 #  1189
>     FW revs 3.68
>     KAT3
>     KBPF3 main reciever
>     KDVR3
>     KIO3
>     KPA3
>     KRX3
>     KXV3
>     S-Meter in relative mode.
>
>     The problem is with the main  RF gain. If I turn down the Main RF
>     gain S
>     meter goes up as expected, the gain is  heard to decrease and seen to
>     decrease by Spectrogram. So far so good.
>
>     When I keep turning the gain down the  S meter will increase to S
>     30 (Rf
>     knob position 10 o'clock) When the knob position reaches 9:30 the
>     S meter
>     drops to S6 and the gain comes back up both heard and seen by
>     spectrogram.
>     Further movement will decrease the gain to zero as heard and seen
>     but the S
>     meter stays at S6. Increasing the gain the reverse happens. This
>     is true in
>     all modes.
>
>     The sub acts normally as heard and seen by spectrogram and the
>     S-meter acts
>     as it should.
>
>     I suspected the main encoder? I set both the sub and main to the
>     main RF
>     gain encoder. The main acts the same as before. I expected the sub
>     to act
>     like the main indicating an encoder problem but the Sub worked
>     exactly as it
>     should.
>
>     During  the Smeter calibration the main RF gain acted as it
>     should. Turning
>     down the gain the s meter goes up, gain goes down as expected with
>     smooth
>     movement no jumps or lags.
>
>     What I have done twice so far without any improvement is
>     Fresh reload of firmware
>     Reset to Factory norms
>     RF Gain Calibration both main and Sub redone
>     S Meter reset using XG2 main and sub
>
>
>     What should I look at next I really thought it would be the encoder.
>
>     Jim
>     VE3AJ
>
>