Update on the apartment complex noise that I tracked down to a new
apartment complex in late October.
Finally was able to meet with the maintenance manager for this facility
this past Thursday, and we were able to track the source of the
interference to an HVAC air handler unit located on the roof of the
complex. Once again used my portable HF receiver (without my external
preamp) with 14" diameter tuned loop, and had to back the gain way down on
the receiver to locate the source. We were able to turn on and off the
unit and observe the RFI turn on and off as we turned the unit on and off.
I then drove back to my house, and we ran the tests again and sure enough
the interference at my house was on when we turned the air handler on, and
RFI went away when the air handler was turned off.
Now going back to the contractor that installed the equipment in an attempt
to better understand the hardware in the unit (hope to get some prints,
etc.) before having them actually attempt to tackle the problem.
Fortunately I have a couple of years of HVAC experience from an electrical
controls standpoint (had to revamp a faulty design for our manufacturing
plant), and suspect this past experience will come in handy during our
Don Kirk (wd8dsb)
On Fri, Oct 24, 2014 at 2:40 PM, Don Kirk <firstname.lastname@example.org> wrote:
> Recently noticed an increase in my noise level on 160 meters (in the
> direction of my 300 degree pointed pennant), and about 3 weeks ago I
> tracked it down to a new apartment complex which is located 0.41 miles
> away. Today I noticed that the signal had a repeating pattern of
> approximately 30 minutes on and 5 minutes off when listening at my house,
> so I jumped in the car and drove over to the apartment complex to make sure
> the signal at the apartment complex had the same repeating pattern and was
> in time sync with the noise at my house. Thankfully it was, and I made
> recordings at the apartment complex today showing I could predict when the
> signal would go off and come back on based on the time pattern I was
> following at my house.
> I have created a website documenting my direction finding activities for
> this broadband RFI case, and uploaded my prediction recording today. Here
> is the link to my simple website that documents this case :
> I contacted the apartment complex today notifying them that I was now 100%
> confident that the broadband noise was originating from their building, and
> will now work with their management to locate the exact source so they can
> follow up with the manufacturer of the equipment for resolution. Based on
> what I have heard so far it sounds like a motor (probably a variable speed
> motor controller), but that's just a guess at this time (sounds like it's
> winding up in speed when it first comes on and you can hear this on the
> recording I made at the apartment complex today).
> Just FYI, and another very interesting one to track down.
> Don Kirk (wd8dsb)
> Topband Reflector Archives - http://www.contesting.com/_topband
Topband Reflector Archives - http://www.contesting.com/_topband