"Auteur" wrote in message
...

You speak of "splatter" from a local Am station, particularly around 5
MHz, from
a nearby location.


I probably used the wrong term here.

If it's a broadcast station harmonic being *truly* transmitted and
*accurately*
received, up at 5 MHz, it would be somewhat unusual. As a broadcast
engineer my
experience is that above the weak third harmonic of the carrier signal
there is
rarely much being transmitted; if so, the power levels would be
exceptionally
low (maybe tiny fractions of a watt at the fifth or sixth harmonic, at
worst.)

I do get the station at exactly three times,but I also receive the
station at other spots not harmonically related.

But my guess is that you probably are experiencing crossmodulation effects
in an
overloaded radio front-end.
The odd thing is I used to live 15 miles from the station and
would receive the station on a old tube communication receiver (Collins)
with only a five foot antenna!

If it is normal to get cross modulation only 15 miles from a AM radio
transmitter, that would imply nobody near a major urban area (Chicago,
Los Angelos,New York,etc) could use a shortwave radio below
7 MHZ. Is that true?

You should probably also use a shielded coax line and a matching
transformer,
with the coax grounded at both the radio and the transformer ends: thus
the lead-
in will not itself act as an antenna for the strong local transmitter
signal.

When I moved to my new location which is approx one mile
from station I do use a shielded coax line and matching transformer. I also
purchased a new receiver a JRC nrd545. I have the problem
with both receivers. The JRC has a switchable RF antenuator of
20 db.

If the station is REALLY transmitting a spur up at 5 MHz (or if there is a
*real* signal being propagated in space due to this station 'interacting'
with a
fence or another carrier, producing an intermodulation product), then by
using a
bandpass filter to reduce the antenna gain only at broadcast band
frequencies
you may not solve the problem: the 5 MHz spur (or whatever it is) won't be
affected. But if the spurious signal is YOUR radio overloading and
crossmodulating, the BC band filter (SW band highpass filter) will help,
or even
completely fix the problem.

I have this trouble with my hypersensitive solid state communications
receiver
and use a simple series shunt filter tuned to a local 50kW station's
frequency,
right across the antenna-to-ground terminals of my radio.

I could try this.

My tube-type radio picked up less of these signals, but did get SOME of
them.
In the case of both radios, reducing antenna coupling did not suddenly
cause
them to disappear: because the signals were really there, not merely
caused by
front end overload. The tube radio heard less of them, because it is far
less
sensitive than the solid-state modern receiver.


AUTEUR



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