40 meter noise question

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  • Updated 2 years ago
What could all this awful noise be? It is very broad banded and sounds like static. All other bands seem good. It does get slightly better and slightly worse at times... could this be station grounding? I am pretty well grounded right next to service entrance. Are others seeing this noise on 40?
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Tony C kc2dis

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Posted 2 years ago

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Mike Hoing

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I have had that on 40 lately and I am believe it Is a strong AM station above 7300.

Mike
N9DFD
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Tony C kc2dis

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ok I thought something was going on.. terrible...
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Paul Burton

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That is lightning static crash.  A frequent summertime evening occurrence on the lower bands. 
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John Leonard

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I'm seeing it too... intermittently. Sometimes I find it on 80 and 160 as well. It has been just "turn the radio off" bad some of the time. I have heard discussion about over the horizon radar causing wide interference at times???
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Tony C kc2dis

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Hello there John! We had a great qso about a week ago. Hope your back is doing better and you resolved that problem you were having with the iphone/ipad disconnecting! - Tony
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John Leonard

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Hi Tony I remember the QSO. Thanks for the well wishes. Ham radio helps to make the World seem like a smaller and friendlier place.
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Varistor

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For one thing, you have way too much RF gain. How can I tell- there is a lot of color noise in the waterfall. Dial down the RF gain until the color noise disappears. The static crashes will become a lot more tolerable.

Summer static crashes are pretty normal in the summer on 40.
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Andy - KU7T

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I did not know that you had to adjust the gain on a Flex, especially down.  I thought that was the reason for the non-existing ATT button?
Andy
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Varistor

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You can control the RF gain via the AGC control panel. See https://youtu.be/Hwm6rszuMis

This is not set it and forget it setting- you have to manage it actively as bands, band conditions, and solar activity/noise change.
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Tim - W4TME, Customer Experience Manager

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That is incorrect.  You adjust the AGC threshold via the AGC-T, which is a feature that operates on the recovered audio.  RF gain is controlled by the RF preamp.  However, adjusting the AGC-T produces a similar effect as setting the RF gain in a traditional radio.
(Edited)
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Tony C kc2dis

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such helpful comments.
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Tony C kc2dis

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Before anyone slams me that I have to much gain... this is set at the Normal (of the three positions available) gain setting. I have followed all AGC adjustments recommended....
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Walt

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I noticed you have the WNB - Wideband Noise Blanker on.  I have had problems with this feature falsing on high-level signals on the band just like what you see on your display.  Try just turning it off and on a few times with about 10 seconds in between and see if the noise crashes change.   You can then play with the WNB levels or just leave it off on busy bands if it turns out that is the cause.

Good Luck and Cheers
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k3Tim

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"rough crowd, no respect" - Rodney D.   :-)   


The pana-display  reminds me of one time when I was operating 'fixed mobile' in the desert and a distant thunderstorm was causing the same display. Off in the distance (15 miles) the lightning bolts could be seen.  Can you hear static crashes in sync with the horizontal lines. 

You're grounding sounds proper - tied to service ground. Assume an RF ground is setup also.

Is the noise mainly 40m only or is 80m effected?

_..--
Tim
   k3Tim / 6
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Tony C kc2dis

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I am just going to chalk it up to environmental conditions as I noticed that last night it seemed quiet.. I noticed that as the sun rises it gets nosier... thanks to all for the suggestions... but the noise really seems excessive only on 40....
(Edited)
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Varistor

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Consider the following variables:

1) Band noise- 40 is indeed noisy during the day in the summer
2) Antenna polarization- a vertical is often going to be noisier than a horizontally polarized antenna. Thus the importance of antenna diversity
3) Common mode noise- buy Fair Rite's Big Clamp-on and wind 9 turns of your coax around it. Read K9YC's cookbook on chokes. Arrow Electronics has the best price on the clamp-ons, part number 0431177081. I buy them by the box and have them on both ends of each and every feedline.
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Tim - W4TME, Customer Experience Manager

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And WNB will not mitigate lightning crashes; only well-correlated noise of which lightning is definitely not.