[Elecraft] [K1] [KNB1] Noise blanker not detected (three dashes ---)

[Don Wilhelm]

Bogdan,

I just returned from Thanksgiving holiday/vacation and saw your post.

The indication of "---" in the menu entry indicates that the 6R/AUX 
signal line is not allowing the KNB1 firmware to communicate with the K1 
main MCU.

I would suggest you check the soldering of RF Board J1 pin 2 and also 
pin 2 of the mating connector on the KNB1 board.

Also check to be certain KNB1 R1 is 180 ohms and is inserted into the 
correct lead holes and well soldered.

You could try a continuity check between Front Panel J1 pin 8 and the 
KNB1 U1 pins 3 and 4 - the resistance should be 180 ohms if all is well.

Double check the orientation of KNB1 U1 - the label used often covers 
the device notch on those 8 pin firmware packages making it easy to 
insert backwards.

The trimmer on the KNB1 board will work whether or not the KNB1 firmware 
is working.

73,
Don W3FPR

On 11/26/2016 5:53 PM, Bogdan - Constantin Lazanu wrote:
> Hello,
>
> This is my first message to this mailing list, so please be gentle!
>
> During the summer and autumn I built my first ever kit: the K1-2 (#3449) + KAT1. Everything worked surprisingly well (being a first-timer and all), I never had any problems. Until now. It seems that I failed in my “build-without-help” venture :)
>
> A few days ago I completed building the KNB1 option and when I got to the “Initial Test” phase I noticed that in the menu, instead of HI/LO/OFF I can only see three dashes (---). The instructions say that the K1 firmware has not detected the noise blanker module and that a possible cause may be that the U3 was soldered in backwards. I assume that’s a mistake - there is no U3. Just a U1, and it’s soldered properly.
>
> Some details:
>
> - The K1 firmware is revision 109
> - The KNB1 PCB is revision Cr
> - U1 on KNB1 has a small paper label with “NB 1.02” written on it
> - Turning the trimmer C2 on KNB1 does vary the band noise and received signal strength
> - There is continuity from KNB1 U1 pins 3/4 to the front panel U1 pin 8 (6R/AUX) - around 182 ohms
> - The voltage between KNB1 U1 pin 1 (VDD) and GND is 6.03V
> - The voltage between KNB1 U1 pin 5 and GND is 5.59V (this is the 6V switch for the noise blanker)
>