[Elecraft] KNB2 trouble...

[Don Wilhelm]

Hans,

The Not Inst message means only one thing - the KNB2 is not communicating
with the K2 MCU.  That comunication occurs over the Auxbus line.  That
signal is present at pin 7 of the KNB2 connector.

I suggest that you check for continuity (and shorts) from the K2 Control
board MCU pin 40 to the KNB2 U3 pins 3 and 4 - you should find about 570
ohms (100 on the control board plus 470 on the KNB2).  If you find anything
different than that, check the path against the schematics to find the
source of the problem.

73,
Don W3FPR

> -----Original Message-----

> I´ve just finished installation of the KNB2 into my K2. When tapping
> the "NB-button" on the K2, the display shows "Not Inst". I have
> re-examined the KNB2 board. U3 is installed/soldered correctly and as
> far as I can see no other components are installed incorrectly or
> backwards. I have also made a few measurements on P12 on the KNB2
> board and on U3, where pin 1 measures 6.1 volts and pin 8 measures 0
> Ohm´s so everything seems to be correct.
>
> The modifications on the K2 RF board in order to install the KNB2
> module are made according to the instructons in the KNB2 manual.
> While examining the board, everything seems to be correctly done
> without any solder bridges.
>
> Still the display shows "Not Inst" while tapping the NB-button.
>