Does the noise appear on one band or several bands? Is it tune-able
thus limited to one broad frequency or just total broadband noise?
You will need to know the frequency of both transmitters and then
perform an IM study. The sum of those two frequencies is doubtful but
the difference could be fall in the ham band(s). You can contact the FM
station and the TV station engineering department and inquire as to when
they have transmitter maintenance scheduled. What ever day or hour of
the night that might be, you need to be listening. If it doesn't go
away, it isn't them. If it does, that doesn't assure they are at
fault. I've seen chain link fences make a nice diode junction and it
radiates like crazy.
Here is a link that will simplify the calculations.
http://radiomobile.pe1mew.nl/?RF_Aids:On-Line_calculators:Intermodulation
73
Bob, K4TAX
On 2/18/2020 6:38 PM, Andreas Wachter via Elecraft wrote:
Yes, I did run the K3 off of a battery and pulled the main AC breaker. Didn’t
make any difference. Thus my suspicion that the RFI is related to the 208 kW
ERP TV station (and/or 63 kW EPR FM station) which are within 1.6 miles and in
direct line of sight.
73, Andreas K6AKW
On Feb 18, 2020, at 10:00 AM, Hank <[email protected]> wrote:
Have you tried pulling your main AC breaker and running your K3 on a car
battery? That way, you are sure that nothing in your house (switching power
supplies, poor mechanical joints, etc.) is creating the noise.
I was able to convince my nearest neighbors to shut down their AC panels also after my
house seemed "clean".
I finally found 2 bad crimped power line connections down the street from my
and a home made fence charge at a goat farm about 300yds behind my house
through the woods. Another ham and the local power company came and helped.
The power company did their work and it cleared up several S units, but
something was still there. Riding around with a scanner tuned to 1800kHz (AM
mode) with no antenna connected yielded the goat fence. The power company came
out with a listening device to verify my findings. I offered to buy the farmer
a fence charger from the hardware store, but he went ahead and did it on his
own - it really helped having the power company there!!
I still have a neighbor with a noisy plasma TV - an MFJ-1026 with a longwire
out the window nulls it out quite well when the TV in on. Eventually the TV
will die (I'm hoping).
Good luck!
Hank
K4HYJ
----- Original Message -----
From: Andreas Wachter via Elecraft ([email protected])
Date: 02/18/20 12:39
To: [email protected]
Subject: [Elecraft] RFI issues
I live about 1.6 miles from some tall antenna towers broadcasting digital TV
(KBCB) at 208 kW ERP on channel 19 (500 - 506 MHz) and on FM (KWPZ-FM) at 63 kW
ERP on 106.5MHz - according to FCC info on KBCB and KWPZ-FM. Ever since I moved
to this QTH a few months ago, I am unable to use my K3: solid S9+ noise on all
bands using a makeshift dipole strung up on some trees outside my house. I’ve
tried to locate the source of the RFI within my home but so far have been
unable to locate any RFI emanating from within my home. Could it be that the
TV/FM stations antenna towers, which are within direct line of sight from my
house, might be responsible for the RFI?
73, Andreas
K6AKW
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