HFU HF Underground

General Category => General Radio Discussion => Topic started by: ChrisSmolinski on November 29, 2016, 1333 UTC

Title: Yet Another !&*%$! Noise Source
Post by: ChrisSmolinski on November 29, 2016, 1333 UTC

All the gory details here: http://www.radiohobbyist.org/blog/?p=1995

Here's the before / after waterfall:

(http://i.imgur.com/PMUv3BC.jpg)

Title: Re: Yet Another !&*%$! Noise Source
Post by: ChrisSmolinski on November 29, 2016, 1456 UTC

I updated the blog post with the results of some more changes, further reducing the noise floor.

Title: Re: Yet Another !&*%$! Noise Source
Post by: refmo on November 29, 2016, 2203 UTC

Nice work, Chris.
Noise is a constant battle, new sources are popping up in my neighborhood all the time.

While finding the noise source and eliminating it is the best solution, sometimes this is not possible (neighbors may not want to turn their Nintendo off, or they prefer to wear laundered clothing :)
If the noise is arriving via the antennas, this would be a great opportunity to test using phase control in the afedri to eliminate the noise.  This would only work best if both antennas are receiving the noise.
I'm also curious if this could eliminate the horrific noise from newer servo-motor washing machines.
If the noise if arriving via the power or usb port then this will not be much help.
Let us know the results if you try it.

I plan to purchase a dual-channel afedri in the near future.

Title: Re: Yet Another !&*%$! Noise Source
Post by: jFarley on November 29, 2016, 2259 UTC

Way to go!

Don't overlook the use of a common mode choke on the antenna;  many NDB DXers swear by them.  I use one out at any antenna which I will use for LF.  I use 40 T of RG174 on an FT140A-W core.  I ground the shield of the coax at the RX side of the choke to a ground rod located at the antenna, but some DXers say it works better in reverse.  YMMV.

Ain't LF fun?