[Elecraft] KNB@ non-operation

[Richard Haendel]

It appears that my noise blanker doesn't operate at all. Receiver gain is fine with the KNB2 installed. It's that when I call for NB operation on impulse noise, there is no noise reduction at all.  I have checked the one-shot and it fires OK, the serial control IC seems to work OK, the control signals out of it correspond to on-off OK.   nb1 and nb2 operation changes the pulse width.  I also see that Q5, the transistor that shorts out the output filter tank, has no bias at all. There is no DC return for the base to ground.  Is this correct? Maybe  the base should not be floated?  Maybe Q5 is open?  Anyone's comments would be appreciated

Rich W3ACO