[ICOM] RE: Good effective noise blankers

[mel martin]

Difficult question to answer... Especially since most "reviews" I've read
are from people trying to eliminate types of noise they are really not
designed for. I've found the blankers in all Icom's I've used good with real
pulse noise such as ignition noise or my neighbors fencer.

For example, with the 746Pro, the NB works perfectly for the fencer...
Taking it from S8 to zilch with the NB level set to *zero*. Same with the
781... I normally set it for narrowest width and lowest level... Though the
lowest level isn't low enough... It will cause IM in some extreme
circumstances... Though I generally leave it on. Previous rigs such as the
765 and 751 as well as some older ones also worked well.

Increasing the level on the 746Pro causes it to have some effect on less
well defined spikes, such as some power-line noise.. But intermod becomes a
problem.

An illustrative story: When Yaesu first introduced the FT-One... It had an
amazingly good blanker... It took out ignition noise, motor bush noise,
fencers and some types of power-line noise... And I never heard it cause any
IM...

However Yaesu got a lot of complaints that the NB "didn't do anything"... So
they "improved it" by lenghtening the time constant of the differentiator
and blanking stage. It now did "something" on more kinds of noise... But you
could longer leave it on due to IM.

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