[Elecraft] K4HD question

[Jim Brown]

On 5/29/2019 6:57 PM, Fred Jensen wrote:
> Noise blankers were designed for repetitive impulse noise, the largest 
> former example of which was ignition noise from vehicles.  They have 
> not ever been very effective against power line hash which tends to be 
> non-impulsive and highly random. 

Huh?

The ARRL book on power line noise specifically states that virtually all 
power line noise is impulse noise, the result of arcing at positive and 
negative peaks of the 60 Hz line voltage. It is NOT random noise. It IS 
quite broadband. Arcing can also occur in big motors, or in any system 
where an arc occurs.

BEFORE the days of microprocessors, switch-mode power supplies, and 
other power control systems that use square waves, nearly all man-made 
noise was impulse noise. NOW, most of the noise that surrounds us is 
from those microprocessors, switch-mode supplies, and other power 
control equipment. That noise is NOT impulse noise, and noise blankers 
cannot act on it.

73, Jim K9YC