[ADXA] noise chasing

Sun Dec 29 19:16:17 EST 2024

Showing a picture from your scope to Engineering, got them going on my first problem.  They didn't like seeing a picture of the problem that was beyond a doubt powerline interference.

Thanks for your help Mark and suggestions many years ago.  I wish you live near me, hi.

73 de jay..

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From: Mark Graves <mgraves at avecc.com>
Sent: Sunday, December 29, 2024 6:08 PM
To: Dennis Schaefer <dennisw5rz at gmail.com>; Jay Bromley <jayw5jay at outlook.com>
Cc: ADXA <ADXA at mailman.qth.net>
Subject: Re: [ADXA] noise chasing

Usually….finding and fixing the noise that is detectable up high (300,50,30 MHz) will solve what you hear on the low bands. Sometimes, but very very rarely, you can have a higher frequency noise generator on the line equipment that is frequency selective. Almost always it’s audio signature is coming from a 120 Hz or 8.3 mS fundamental that can be seen after demodulating and viewing on your radio audio scope or oscilloscope for verification of power line vs harmonics interferences.

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________________________________
From: adxa-bounces at mailman.qth.net <adxa-bounces at mailman.qth.net> on behalf of Dennis Schaefer <dennisw5rz at gmail.com>
Sent: Sunday, December 29, 2024 5:56:37 PM
To: Jay Bromley <jayw5jay at outlook.com>
Cc: ADXA <ADXA at mailman.qth.net>
Subject: Re: [ADXA] noise chasing

Thanks, Jay - I can easily try that.  It does 432 and I can even use a small yagi to narrow things down.  The only problem is that the source is some unknown distance beyond the back fence, but if I can pick it up well enough to use the yagi to get a fix, that would be great.  I might be able to drive around to the other side and get a couple more fixes for triangulation even if I can't drive right up to the transformer and pole.  I need to look at Google Earth and see just where the lines run over there.

73,
Dennis

On Sun, Dec 29, 2024 at 4:44 PM Jay Bromley <jayw5jay at outlook.com<mailto:jayw5jay at outlook.com>> wrote:
Hi Dennis,
Try the 817 on the highest band, I think it has 70 cm?  Anyway, many of the test gear these power companies use are 350 MHz receivers with built in attenuators.

Stan K5VR loaned me his HT that has AM receive on 70cm and we found the problem just walking up and down the road.  Need to borrow it again.  Stan and I found problems up to ¼ to 1/2 mile away.  However, since Ozark has upgraded many of the power poles it never stays foxed for more than a few weeks!  They replaced every other pole or several in a roll.  The old poles have old hardware that was stressed during the upgrade.  Then you add all those new surge suppressors that are arching and you have a real mess.  They say they need the protectors to keep the equipment from so much damage, but if they are bad and arching that isn't going to protect anything!  I like the idea or protection, but only if they are being maintained!

My power company doesn't have the training or the expertise to really maintain the system.  I hate calling them, now on a first name basis with many of the employees and have their numbers in my contact list, hi.  Only once when I interfaced with one of their engineers did I feel like the problem was being addressed!

Sadly, it is a fact of life we now live in.  Some of the better power companies are now using drones find broken hardware and that seems to be a game changer!

73 de jay/w5jay..

________________________________
From: adxa-bounces at mailman.qth.net<mailto:adxa-bounces at mailman.qth.net> <adxa-bounces at mailman.qth.net<mailto:adxa-bounces at mailman.qth.net>> on behalf of Dennis Schaefer <dennisw5rz at gmail.com<mailto:dennisw5rz at gmail.com>>
Sent: Sunday, December 29, 2024 2:36 PM
To: ADXA <ADXA at mailman.qth.net<mailto:ADXA at mailman.qth.net>>
Subject: [ADXA] noise chasing

Randy, W5ZJ, has given me some good advice about Pennant antennas and even sent me some ferrite binocular cores for matching transformers.  I'm in the process of figuring out how to orient the trial Pennant.  I thought my noise sources were mainly from N to E but weather kept me from getting out and doing much snooping.

I rotated the yagis and then went out today with an FT-817 (handheld HF rig) and a 20M antenna.  I walked all around listening on 20 with good sensitivity and 80 with poor sensitivity because of the 20M antenna.  I verified what I was seeing on my yagis - the main noise source is to the South.  There is a house back there, about 700 feet away.   The poles and transformers to the N and E are quiet.  I didn't walk right up to the houses they are associated with, but those seem quiet also.

The noise to the S has that raspy, pulsing noise I usually associate with power line noise or some kind of arc.  I know the noise is strong on HF and 6M but I'm limited on checking on 80 and 160.  I could attach something to the FT-817 that would be better on 80 but I think the source to the South is a broadband noise signal.

The other hot spot is my electric meter, but I only detect noise when the 817's antenna is within a few inches.

I also have a TinySA spectrum analyzer, which is a truly remarkable instrument for the size and price, but it doesn't seem to be sensitive enough for outside checking.  I can hold it up to a computer or router or wall wart and see the spurious emissions clearly but this is with the little antenna just inches away.  I haven't begun to analyze things associated with my house yet, but I will get to that.  I have a lot of FT-240-31's and I'm sure some will be needed.

My inclination now is to put the Pennant with its null to the South.  It should cover EU and AS that way and I could get an idea how it works.  I may try to make it reversible but I want to keep it simple for now.

73,
Dennis/RZ

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