My recommendations:
1. Make sure it is not your receiver. If your receiver has a passive
attenuator(resistor pad), go to a steady signal like WWV and switch it
in, and see how much attenuation it supplies. Then dial in your 1940 kHz
signal. Switch in the attenuation. If the signal drops the same level as
you saw in the WWV test, the signal is coming via your antenna. If for
example, your attenuation showed 10 DB attenuation at WWV, and you show
a 20-30 drop at 1940, your receiver is into overload.
2. Lets say it is not your receiver. Where is the signal coming from?
Possible choices:
-It is produced at the broadcast transmitter site. Plenty of things
to go wrong there. Been there.
-It could be produced by some thing some place else, including the
proverbial rusted fence.
-it could be produced by something electronic in your house or
neighborhood. These are always fun to trace down. Your receive location
is definitely in the very strong field of the radio stations.
My guess is your will have to DF this. Please be very careful to not
assume where the signal is coming from.
Of note, both AM stations are what is called a DA-2 directional.
Different patterns day and night. WKDM changes power at night (actually
goes up from 5 kw to 13 kw)
Does the level of the signal change at daylight or sunset? When it
changes, it will be a sudden change. For the most part, the stations
will go off the air for 1 second or so.
You have a bit of research to do. There is a lot of AM broadcast RF
within a 2mile radius there in the Meadowlands.
Those two AM's, should have a calibrated field intensity meter, which
could verify the level, and is also directional.
But asking for help is the key.
Tom Bosscher K8TB, retired from over 50 years of pushing the RF out on
the broadcast bands.
p.s. side note. The first AM I worked for full time was on 1300 kHz. We
had complaints of a S9 + signal on 3900 KHz (could have been kc/s back
then!). My boss and I read a very weak 3rd harmonic at our own driveway
at the transmitter site. In his driveway, we very much saw a very strong
signal. On a hunch, I looked at his downspouts. All aluminum. I rattled
them, and the signal went away. The fellow ham then asked about the S
0.12 signal left on 1300. My boss said, "use it to calibrate your rig!".
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