[RFI] 20M Hash

w4lde w4lde at numail.org
Mon Dec 21 14:17:49 PST 2009


After reading your message below it brought back memories of exactly the same thing happening to me in the fall of 2008.

One morning in Step 08 I turned on the rig and bang there was hash all over 20M as high as S-9.  The only thing I could use that band for was JT65 and a few other digital modes.

What I started doing was logging the time and signal strength of the noise and also checking other bands, did it every day looking for a pattern, 80M was a S-4 to 5 40M was a S-5 to 7 and 15M and up wasn't to bad.  20M was the band most hurt by the noise.

At first I suspected the power company, I took my hand held and a 440 3 element and off I went, boy did I find noise all up and down the power lines and one pole in question produced lots of noise.

To my surprise the power co had three (3) trucks to my house within a day of my call.  My spirits went up since now the problem would be fixed.  Unfortunately there equipment to find the noise wasn't better than mine and at one time asked if they could use mine, they were really trying to find the problem.  They did go out and check about six (6) poles using their bucket trucks, and yes they indeed did go up and down checking the connections, but they indicated that they could not find anything wrong and threw their hands up at this one and wished me good luck.

Since there is no homes within 1000ft of me I started checking everything in my house one breaker at a time with no luck.  Then I started house hunting up to 1/2 mile away looking for a noise source, again no luck.

After about 3 months of this problem is when I started to log some intermittent noise activity.  One day it completely disappeared.  Then it was back, but still I saw intermittent activity like there was a lose connection somewhere.  I was still thinking power!

Thats when thing started to change after 3-months of this noise, it was gone.  The XYL on the way home said that there was a TV cable truck out on one of the poles I had suspected.  No I thought it can't be from a TV cable can it?  Well I am now convinced it was noise from the overhead cable (TV-internet) main lines.

One day I saw the cable guys out working on the lines and I ran to the rig and sure enough the hash was back, then gone, then back so I jumped into my car and off I went to were they were working.  Talked to the supervisor he did indicate that they had problems with line amplifiers and they were replacing them plus were going to run about a 1/2 mile of new cable hanging from the power poles.  Another Tech made the statement that the internet phone service operated a two different frequencies, 24Mz and a very high one which I can't remember.  Broadband amplifiers emmmm, were do they start to work?

Anyway after they did run the new cable and replaced some three line amplifier's the noise is gone and it now 12 months later.  My typical noise level on 20 is S-0, 80M S-2 to 4 evenings and on 40M its S-0 to 1 in the mornings and S-1 to 3 in the evenings.
Moral of this story is don't rule out anything.

Don't give up hope, start looking yourself using your AM car radio, then your FM and a VHF hand held tuned to 133Mhz and then 300Mhz, scan your neighbors homes, maybe a new plasma TV set for XMAS, battery charger, bad door bell transformer.  Also check you transformers supplied with your cable box converters and Internet router.  I had one transformer that produced S-6 noise when I connected it to the shack power, brand new N wireless router, had another transformer in the junk box and noise disappeared.  Check your home one breaker at a time.  If indeed you suspect the power system ask for help from the Service manager, when I did I pointed to the possibility of saving dollars on their end and that help get their attention.

I can only offer encouragement at this time but you will prevail.

Have a very happy holiday season and let us all know how things are going.

73 de


Message: 1
Date: Sun, 20 Dec 2009 23:05:10 -0600
From: "W9RPM" <john at w9rpm.com>
Subject: [RFI] 20M Hash

Hi, I was wondering if anyone could give me some insight into Noise/RFI 
across the whole 20M band. The other bands don't have it on. It started 
about 2 weeks ago. Holds pretty steady, but is a little stronger in one 
direction. It is S6 most all of the time, and S9 to one direction.  Trying 
to determine possible causes. It is a frying sound almost. Thanks- John 

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