OK.....what is a "BB service"??73,Gary K9GS
-------- Original message --------From: Gedas <w8bya@mchsi.com> Date: 12/23/20
12:57 PM (GMT-06:00) To: rfi@contesting.com Subject: Re: [RFI] QUESTION I
would also disconnect the 75-ohm coax that connects up to the modem if you have
BB service as that line is hot with all kinds of RF.Gedas, W8BYA EN70JTGallery
at http://w8bya.comLight travels faster than sound....This is why some people
appear bright until you hear them speak.On 12/23/2020 1:28 PM, Eddie Edwards
wrote:> As Jamie, WW3S pointed out with the Telephone/cable-modem UPS as RFI
Sources even when AC power is turned off at the main breaker panel, some other
home UPS units for computers or any smart appliances are also possible sources
as they have back-up batteries converting DC to AC power. Just killing AC
power may no longer eliminate our homes as a possible RFI source.>> 73, de ed
-K0iL>> -----Original Message-----> From: RFI
<rfi-bounces+eddieedwards=centurylink.net@contesting.com> On Behalf Of WW3S>
Sent: Tuesday, December 22, 2020 17:00> To: donovanf@erols.com> Cc:
rfi@contesting.com> Subject: Re: [RFI] QUESTION>> One caveat to kill all the
breakers....if you have phone service along with cable tv, you probably have a
battery backup in your modem to provide phone service in the event of a power
outage....that may be one of your sources of local rfi, and you may spend weeks
trying to track it down outside your home, when it really is just sitting on a
desk in the home office .....cable company changed out old modem for new
one....at least for now, the rfi from my home is gone, but the other 110+ homes
in the subdivision, that’s a different story....>> Sent from my iPad>>> On Dec
22, 2020, at 4:53 PM, donovanf@erols.com wrote:>>>> Hi Gary,>>>>>> The process
for identifying this type of RFI is the same as for any>> other RFI, except you
need to use your transmitter to excite the RFI generating source.>>>>>>>> First
verify that the RFI is not coming from your own home>>>>>> - kill all of the
circuit breakers in your home and power up ONLY your>> transmitter. All
accessories should be DISCONNECTED from AC power. You>> may need to use your
amplifier to produce enough RF to trigger raspy>> harmonics from RFI generating
source.>>>>>> - Put your transmitter on the air, keying it from a memory keyer
is a>> good approach>>>> - if the raspy harmonics have gone away, start turning
on the circuit>> breakers in your home, one by one, until the raspy harmonics
reappear.>>>>>> If you determine that the RFI is not being generated in your
own home,>> turn your directive antenna in the direction that produces the>>
strongest raspy harmonics. A sensitive spectrum display such as the>> Elecraft
P3 helps immensely.>>>>>> Then use a portable receiver to hunt for the RFI
source along the line>> of bearing identified by the previous step.>>>>>> Good
luck>>>>>> 73>> Frank>> W3LPL>>>> ----- Original Message ----->>>> From: "Gary
Johnson" <gwj@wb9jps.com>>> To: rfi@contesting.com>> Sent: Tuesday, December
22, 2020 12:48:16 AM>> Subject: [RFI] QUESTION>>>> That’s easy. RF is picked up
on the AC lines then enters any nonlinear device plugged into those lines, such
as a walk wart. There, RF is rectified, harmonics are generated, and that’s
mixed with all the garbage on the power line, then re-radiated via conducted
emissions. Many harmonics are normally expected. This is the classic problem
for any SO2R or M/M station.>>>> Case study: At 8P5A, Tom has very little
ancillary stuff plugged in and yet he had your problem. He traced it to a
single LED light. Once removed, the harmonic garbage disappeared.>>>> Gary
Johnson NA6O>> gwj@wb9jps.com>>>>> On Dec 21, 2020, at 4:06 PM,
rfi-request@contesting.com wrote:>>>>>> From: David Eckhardt
<davearea51a@gmail.com>>>> Subject: [RFI] QUESTION>>>>>> I'm out of ideas on
this one! Where does the raspy modulation come>>> from on the harmonics which
changes with position in my radio room on>>> a battery operated receiver?>>>>>>
Situation:>>>>>> transmit on 7.010 MHz>>> receive on second harmonic,
14.020>>>>>> transmitter: IC-7300>>> receiver: IC-7610>>> and reversed>>>
Demod: CW or SSB (or AM, for that matter)>>>>>> Fundamental sounds clean.
Second harmonic sounds modulated by 120-Hz>>> (and a few harmonics of the line)
and quite raspy - pretty awful.>>>>>> Receiver: portable battery operated
receiver (Grundig G3) with same>>> transmitters: I can walk around the room
tuned to the second harmonic>>> and find places in the room where things are
clean and other>>> positions where the second harmonic (and third) sound awful
with 120>>> Hz raspy 'modulation'. Any idea how I can account for this
localized>>> behavior? I'm out of theories.>>>>>> Dave - W?LEV>>
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