[Elecraft] How can the KNB2 be tested?

[Karsten Eppert(DK4AS)]

I have the KNB2 built and installed. I can turn it on/off, set the 
theshold....everything.
On 40m , with low threshold, I get "ghost"-signals. The manual 
recommends to spend an additional capacitor. OK.
But what I expect - the blanking of noise - does not happen at all. As I 
have no Noise-source, I tried to switch workspace-lamps on and off. That 
gives me beautiful strong clicks in the receiver. Unfortunately I have 
the same strong clicks when the KNB2 is activated. Nothing is blanked.

Is there a way to test the KNB2? Anything that can be measured? Do I 
need a different noise-source?
73
Karsten
K2 #4764