[ICOM] Icom rigs and atmospheric noise

[John Geiger]

Here is a question for the list about there
experiences with Icoms.  I recently picked up an Icom
740 based on its reputation for having a quiet
receiver and a great NB.  I am thinking that I have a
problem with power line noise, or something like that,
and so far the power company has done nothing really
to try and fix it.  I am now wondering if maybe my
expectations are too high.

According to the ARRL review of the 740, its MDS
(noise floor) is -133dbm with the preamp off, and
-141dbm with the preamp on.  They don't mention what
bad that is on.  On the higher bands, with the preamp
off, I am seeing a noise level around S1 or so.  Very
nice and quiet, and the notch filter will remove that
even more.  When I turn the preamp on, the noise level
will rise to S4 or S5 sometimes.  I noticed this
yesterday during the NAQP.  It pretty much sounds like
regular static, though.  No buzzing or anything like
that.  Given the MDS numbers from the ARRL review,
would S4 be an expected atmospheric noise level with
the preamp on?  I generally run it with the preamp off
on the lower bands, and it does seem fairly quiet
there, although I was seeing some S8 bursts on 75
meters last night.  

I guess I am starting to think that maybe I really
don't have much power line noise.  Maybe I just have a
sensitive rig with some good old mother nature static,
and a little bit of the crud you get from living in
the city with neighbors on every side.  I have been
driving myself half crazy trying to find a rig with a
S1 or lower noise level, and maybe I just have too
high of expectations.  I have a short memory and
cannot really remember what things were like in other
locations I lived in. Of course I probably had less
sensitive rigs also.

Any opinions?

73s John NE0P


		
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