[Elecraft] KX3 VFO tuning noise reduced or eliminated

[Rich Heineck]

Mike,

What you would be checking for is opposite sideband suppression and 
you'll need a very strong single tone signal source.  S9 + 20 or 
thereabouts is a good level, and this can be on or around 20m. There's a 
procedure to do the calibration in the KXFL3 installation instructions, 
but the following is a fairly quick approach if you have a handy signal 
to use.

- Turn AGC MD (menu) to OFF.  Set AF gain to 1 before tuning to a strong 
signal.  Set the PBT BW for 2 kHz, which should be FL1 setting.

- Set mode to CW and  check your PITCH setting.  Multiply the pitch by 2 
and set up RIT for minus this amount.  For example, if PITCH is 550 Hz, 
set RIT to -1.10 kHz.  Turn RIT OFF once it's set up.

- Tune to the signal and adjust the preamp setting if needed to try and 
get the level to S9+10 or more.

- Turn RIT on to hear the opposite sideband.  The signal should be very 
weak and likely close to the noise floor.  You'll also normally need to 
turn the AF gain way up to hear it.

- Turn the AF gain back down then reduce the PBT BW so you get a change 
to FL2 and then again to FL3.  The opposite sideband should be very weak 
for those settings as well.  If it jumps up considerably, or if it's 
just not very weak for any of the BW settings, a calibration would be 
helpful.  In that case, follow the procedure in the KXFL3 installation 
instructions.

- Don't forget to turn AGC back on when done :-)

73,
Rich  AC7MA




On 07/08/2013 10:12 AM, Mike WA8BXN wrote:
> The instructions suggest that realignment of the filter may be necessary if
> some of the capacitors are pressed on the board. Is there any simple way to
> tell if such realignment is necessary? Is it very likely that if those parts
> are not touched realignment is not needed?
>   
> 73 - Mike WA8BXN
>   
>   
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