Just a quick follow up on my Case #2 which was broadband interference on
160 meters which was visible as wide repeating bands of interference on 160
meters. As previously mentioned I tracked this interference down to my
neighbors home, but had difficulty finding the guilty device using DF gear
in the house.
This evening I finally resorted to shutting off one breaker at a time to
help identify what part of the house was the likely source, and it turned
out to be the Master Bedroom (turning off the Master Bedroom circuit
breaker was the only breaker that had an impact, and it totally killed the
interference). We then went to the bedroom with my DF gear and detected
strong interference from the area of the TV, cable box, and Amazon "MXQ
Smart TV Box Mini PC Streaming Media Player" that were located in the
Master Bedroom.
Unplugging the MXQ Smart TV Box power supply killed the interference. I
tried a Delta 20DRGG5 input line filter between the MXQ Smart TV Box power
supply and the wall outlet, but this had very little impact on reducing the
interference. I then wound 11 turns of the 2 conductor extension cord that
fed power to the MXQ wall wart power supply (SMPS) through a 2.4" OD
Fair-Rite #31 mix toroid core, and this immediately killed the interference
(wanted to wind 14 turns but that was not possible with the existing plug
on the extension cord). My neighbor was amazed at how simple the solution
was for eliminating the RFI, and I have to admit I was surprised how
quickly we solved the problem.
Note : The power supply feeding the MXQ Smart TV Box is a Model: BM-118A
with a rated output of 5 Vdc, 2amps.
When time permits I will create a simple website to document this case
similar to some other cases I have solved. It will include a radio
spectrum plot showing the interference, a picture of the guilty equipment,
as well as pictures of the simple toroid core filter we wound that
eliminated the interference (ugly but very effective).
Stay tuned for details on the website URL I create for this case.
Don Kirk (wd8dsb)
On Fri, Aug 5, 2016 at 9:32 AM, Don Kirk <wd8dsb@gmail.com> wrote:
> Two new cases of RFI this week.
>
> *Case #1*
> Within the last year I tracked down and eliminated 160 meters RFI that was
> being generated by an injection molding machine located about 0.5 miles
> from my house (generated by the AC servo drive controller). This week I
> noticed an identical interference pattern on 160 meters coming from the
> same direction as before (using my 3 fixed pennants that provide amazingly
> accurate signal direction). Then I confirmed the interference was coming
> from the injection molding facility using my portable DF gear.
>
> I called the injection molding facility yesterday, and after a little
> prodding, I was told a new injection molding machine was installed two
> weeks ago (I was pretty sure this was the case as I knew they were going to
> purchase 3 new machines this year based on my previous contact I had with
> this facility). I'm sure they will have to install a 3 phase in inline
> power filter on this new machine similar to what we did on the first
> machine, and will soon follow up with the owner of this facility.
>
> *Case #2*
> This week I also noticed a new interference pattern on 160 meters coming
> from the S.E. (heading of 140 deg) and using my portable direction finding
> equipment I tracked it down to my neighbors house and the suspect source
> inside their house is located about 140 feet from my RX antennas. I was
> able to isolate the problem to the equipment inside their house associated
> with their TV/internet service and/or wireless router (all located within
> feet of each other), and our next step is to start unplugging these devices
> until we find the guilty party (ran out of time last night to do this, and
> will tackle this when we both have free time). Turns out that some of this
> equipment was relocated within the last two weeks which probably explains
> why I just recently noticed it.
>
> P.S. it really is nice having 3 identical point fed pennants on 160 meters
> each pointing approximately 120 deg different than the other, as it
> provides almost instantaneous signal direction (just takes one signal
> strength reading on each antenna to determine the heading, and this can be
> done within a couple of seconds).
>
> Just FYI,
>
> Don (wd8dsb)
>
>
>
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|