[Yaesu] Noise blanker recommendations

[Dr. Gerald N. Johnson]

Unfortunately that is the way a conventional noise blanker works. It 
shuts down the receiver for the duration of the noise pulse. If there is 
only one signal in the first IF bandpass (where it usually works with 
tens of kHz bandwidth) then you hear that signal decently without too 
much loss from the notches. If there are any strong signals in the first 
IF bandpass (and that has to be fairly wide for the noise blanker to 
have fast rising pulses to work on) they get chopped and turn into splatter.

I do use the noise reduction option of the DSP in my FT-857Ds expecially 
when trying to copy weak signals on 10 GHz but don't have to use the 
noise blanker on that band and it helps. I also use the DSP to set a 2.1 
kHz low pass filter on the post detection audio. Decades ago I created a 
switchable passive low pass filter for the speaker circuit and that 
helped too by removing the higher frequency components not needed for 
communications. I don't like that low pass filter on FM but its great on 
SSB and CW. http://geraldj.networkiowa.com/papers/speakerfilter.pdf
I do use the noise blanker on 6m sometimes but not with a wide open band.

There are noise canceling speakers even in a nearby truck stop for CBs. 
I haven't tried them. Advertised in the October 2017 QST by DX 
engineering. Made by BHI, http://www.bhi-ltd.com

There is RF cancellation that can work for a fixed antenna and a fixed 
location noise source. Basically it adjusts the phase and amplitude of 
the noise from a second antenna (good enough to hear the noise but poor 
for desired signals) and cancels the unwanted noise. MFJ makes a couple 
models MFJ-1025 and MFJ-1026 according to their advertisement in the 
October 2017 QST. Not automatic devices, takes manual adjustment.

73, Jerry, K0CQ


On 10/22/2017 9:27 PM, John Geiger wrote:
> I was making a rather serious (given my small antennas) effort today in the
> Illinois QSO Party and had to deal with this intermittent noise I have here
> for pretty much the entire contest.  It is a raspy, hash type noise that
> will be on for 2 or 3 seconds, then will end, but come back every 20 to 30
> seconds.  I  have figured out it is not in my house, and doesn't seem to be
> power line noise.  At one time I thought I had localized it to a house
> about 4 houses to the west of me, but the house is now unoccupied, but the
> noise is still there.
>
> Anyways, I was using the Kenwood TS950SD which I just picked up, and it is
> a great rig with lots of receiver tools.  The noise blanker pretty much
> knocked out the noise, but it also produced plenty of IMD products when the
> band got busy and put a raspy sound on many of the signals, so I was having
> to turn the NB off and on trying to make the signals as best as I could
> with this noise.  Even engaged the attenuator a few times on 40m which
> helped a little, but also weakened signals.
>
> I have had a slight windfall recently and can afford to get a newer, better
> rig if I want.  Are there any recent Yaesus that have noise blankers that
> take out many different types of noise, but don't mess with the receive
> signals and receiver dynamic range?  I wonder if the DSP based noise
> blankers are better?  An older rig would be ok also if it would meet those
> criteria.
>
> 73 John AF5CC
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