[RDXA] skype and HF noise (interesting use + query)

[Doug Stewart]

Hi Mike,
Good job identifying the source, and an awesome use of technology to get there. Is the noise on the whole time the neighbors furnace is running, or just when it starts?  If it is a typical forced hot air it will have a hi voltage starter that will generate a huge amount of wide band RF but only until the burner ignites.  Then the blower motor will kick in which is what I expect you are hearing.  It may be the motor itself or a bad ground somewhere, or maybe a design issue as those are out there also.  It may be in your best interest to politely inquire about the furnace and the installation and what you are seeing and offer to help fix it. (it may be causing interference in their house as well)  This is a very delicate situation as you have pointed out and if handled or introduced the wrong way could be bad for long term relations! I'm sure you will get to the bottom of it.

There is a lot of articles and references on this online.  This one was top of the list:

 http://www.eham.net/ehamforum/smf/index.php?topic=56473.0

Good luck,
Doug
N2BEG



-----Original Message-----
From: RDXA [mailto:rdxa-bounces at rdxa.com] On Behalf Of n2ujn at rochester.rr.com
Sent: Wednesday, November 27, 2013 7:34 AM
To: rdxa at rdxa.com
Subject: [RDXA] skype and HF noise (interesting use + query)


All,

last Feb 24, on 28.4 MHz and 21.3 MHz, I suddenly began experience intermitten S1->S8 noise.  The noise was almost like the sudden onset of a quiet carrier.  

Initially, I was completely puzzed (a month or so).  Then, as it warmed up, the intermittent noise began subsiding, then, gone completely all summer.

But, over the last week it is back.  Very bad and more on than off, but, still on and off.

So, this morning I turned on my iPad logged into skype and pointed it at my transceiver while tuned to 28.4 Mhz.   

Then, I awakened my daughter had her log into skype and call me on video call so I could see my transceiver from outside the house.

Then, I stood next to my neighbors heater exhaust which is located on the side of his house next to my garage.

While watching my transciever S meter via skype, I managed to completely correlate the onset of noise with the onset of my neighbors heating system via the sound from the exhaust.  Perfect correlation with noise onset at the transceiver with the onset of the heater exhaust from my neighbors home.

So, good news, the puzzle: where is the noise coming from is solved.

Bad news:  I expect heating systems are pretty complex, and, when they emit RFI could be a lot of places.   I had sent this information off to Paul who has a lot of experience in electrical engineering but thought I would ping the reflector.

Has anyone experienced RFI steady onset noise from a furnace system, I am guessing a new one since it just began last Feb 24th?

Any ideas for resolution would be great before I stop by my (fortunately extremely nice) neighbors home?

Thanks in advance everyone. 

Mike

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