[ICOM] Icom 7000 noise blanker

[John Geiger]

Thanks for the information Frank.  It might be line noise that I am dealing 
with as it did seem to quite down briefly when we had a little bit of rain 
last week.  I thought line noise was usually more broadbanded. Have you seen 
it where it would be limited to 6m and not affect the HF bands at all? 
Guess I need to get out an HT and do some more checking.

73s John AA5JG

----- Original Message ----- 
From: "Frank N. Haas KB4T" <kb4t at arrl.net>
To: <Icom at mailman.qth.net>
Sent: Sunday, July 17, 2011 4:58 PM
Subject: Re: [ICOM] Icom 7000 noise blanker


>
> I use an Icom IC-7000 as the principal RFI location tool in my company
> truck. The Noise Blanker (NB) will reduce but not usually eliminate strong
> power line noise.
>
> I work for a large electric utility as a power line interference
> investigator. In most cases, I can locate an offending pole by driving
> around while listening to the interference on the 7000 (7K) in AM mode at
> the same frequency at which the customer reports hearing the interference. 
> I
> usually leave the NB ON, yes, ON while listening for RFI at lower
> frequencies. The NB does a good job of reducing (not eliminating) the
> ignition noise of the truck engine while allowing me to clearly hear the
> power line interference signal.
>
> I'm not sure why the NB is more effective on the engine ignition noise 
> than
> the power line noise. Perhaps the ignition noise is more periodic than the
> power line noise and the NB is able to more easily lock on the engine 
> noise
> as a result.
>
> As I get closer to the source, I increase the frequency at which I'm
> listening, often going to 144 MHz in AM mode. If I can hear the RFI at 144
> MHz, I turn the NB OFF because it is no longer needed and I can more 
> clearly
> hear the RFI. With VHF copy, I can usually drive right up to the source, 
> be
> it a pole, house, barn, office building...whatever.
>
> If I can't hear the RFI at VHF frequencies, the 7K is still a great tool 
> to
> get very close to the source. I have other handheld tools to effectively
> pinpoint the source on foot.
>
> When not tracking down RFI sources, the 7K serves me well for Mobile CW &
> SSB contacts, Shortwave Listening and getting "Smokey" reports on the 
> super
> slab. The extraordinary frequency range and infinitely variable 
> selectivity
> are a huge benefit on the road in my business.
>
> The only thing I don't like about the NB, and this is true of any recent
> Icom HF rig, the level setting is critical to avoiding the spurious junk
> that can be produced by the NB. The NB Level setting has to be set to a
> point where you get decent NB action but a minimum of spurious junk in the
> passband.
>
> The junk to which I refer is the thumping hash one hear's in the receiver
> caused by the noise blanker's action in the presence of strong adjacent
> frequency signals. The Icom noise blanker will produce this hash even with
> narrow selectivity settings where the adjacent strong signal isn't even in
> the passband to which one is listening.
>
> Generally speaking, I try NOT to use the NB if I can avoid doing so. The
> hash produced by the NB can be worse than the interference it's trying to
> reduce (not eliminate.) I wonder how expensive the next generation of Icom
> HF rig will be when they finally figure out how to make a noise blanker 
> that
> doesn't add to the problem and only solves it.
>
> I would say that the artifiacts produced by the Icom NB in nearly all HF 
> rig
> models is Icom's Dirty Little Secret. Fortunately, there are so many pro's
> to outweigh this con, that I still like all of the Icom rigs I own. And I
> couldn't do my job as efficiently each day without the 7K, flawed NB and
> all.
>
> 73,
>
> Frank N. Haas KB4T
> Utility Interference Investigator
> Florida
>
> =======================================
> Original message:
>
> Date: Fri, 15 Jul 2011 22:14:42 -0000
> From: "John Geiger" <aa5jg at fidmail.com>
> Subject: [ICOM] Icom 7000 noise blanker
> To: "ICOM Reflector" <icom at mailman.qth.net>
>
> How does the Icom 7000 noise blanker do on taking out line noise?
>
> 73s John AA5JG
>
>
>