[Elecraft] eHam.net forum message

[Duncan Carter]

Regarding key clicks.  I suspect this may vary considerably with the 
specific circumstances including the likelihood of considerable 
variations in the individual transmitter rise and fall times and and the 
roofing filter bandwidths.

Last November, I think, I read a suggestion about blanking key clicks 
suggesting mainly the more extreme dsp settings, especially 3-7.

In the following 160 contest, one of the local contesters who uses Yaesu 
equipment was kind enough to furnish loud key clicks that I was able to 
test with,  At the time, I had the nominal 250 Hz filter and the 2.8 KHz 
filter with the 2.8 KHz filter being ineffective.  Since I didn't have 
an antenna set up for transmitting at the time, I was free to 
experiment.  The best blanking effect was with the 3-7 dsp setting and, 
at roughly 130 Hz spacing from center on the high side of the 250 Hz 
filter which has asymmetrical slopes, the click and other spur level was 
reduced by  four S-units on the K3 meter, allowing me to  copy weak 
signals at that separation.  The  analog blanker may have some effect on 
the blanking of clicks but it wasn't nearly as obvious as the dsp 
blanker.  Since then, I've acquire a 500 Hz filter but I haven't had the 
chance to test it in the same combat conditions. I don't know if the NR 
would help with the 500 Hz filter; it does on other impulse noise 
whereas the NR is fairly useless at 250 Hz.

Dunc, W5DC