5th Harmonic
 

I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

Roland, NK2U

Roland Stiner wrote:
I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

Roland, NK2U



I believe this quote from the rules should help:

(b) Emissions 10.2 kHz to 20 kHz removed
from the carrier must be attenuated
at least 25 dB below the
unmodulated carrier level, emissions 20
kHz to 30 kHz removed from the carrier
must be attenuated at least 35 dB
below the unmodulated carrier level,
emissions 30 kHz to 60 kHz removed
from the carrier must be attenuated at
least [5 + 1 dB/kHz] below the
unmodulated carrier level, and emissions
between 60 kHz and 75 kHz of the
carrier frequency must be attenuated
at least 65 dB below the unmodulated
carrier level. Emissions removed by
more than 75 kHz must be attenuated
at least 43 + 10 Log (Power in watts) or
80 dB below the unmodulated carrier
level, whichever is the lesser attenuation,
except for transmitters having
power less than 158 watts, where the attenuation
must be at least 65 dB below
carrier level.

The above is from section 73.44 of the 1-98 edition of the FCC rules. I
doubt they have changed since then.

Charlie
--
To respond by Email remove never- from address

On 11 Apr 2005 02:37:50 GMT, "Roland Stiner" wrote:

I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

Roland, NK2U



They suppress them very significantly. You are probably in a position where
you have (depending on the antenna of course) very high signal levels, and if
you have a long wire or similar, you might have just a touch of corrosion
somewhere that is causing the problem. (Along with front end overload..)

Amazing what a volt of signal will do to the front end of a radio designed for
a millionth of that will do...

Have the same problem with WBT here in Charlotte. Move out of the main lobe,
and all is well, stay in the peak signal area, and get WBT everywhere. The
cable TV ends up with WBT in almost all their local analog signals.. Of
course, there it looks like stripes of noise.. (Diagonal banding.)

Roland Stiner wrote:
I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

47CFR73.44:
"... Emissions removed by more than 75 kHz (from the station's carrier)
must be attenuated by at least 43 + 10 Log (Power in watts) or 80 dB
below the unmodulated carrier level, whichever is the lesser
attenuation,..." (followed by an exemption for powers of less than 158
watts)

In WOR's case the formula would yield an attenuation of 90 dB so the
80dB figure would apply.

Are you certain the harmonic isn't being generated locally? (possibly
even in your receiver)
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

Roland Stiner wrote:

I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

Roland, NK2U


"Receiving them loudly" is rather vague. How many watts are they
transmitting? What kind of antenna pattern? They are probably
operating within specs but overloading the front end of your radio.
Have you tried a tuned trap at 710 KHz? Its simple to build one from a
junk AM radio. Remove the ground connection from the antenna coil, add a
couple antenna connectors with the center pins connected together.
Connect the antenna coil wire you removed from the ground connection to
one of the antenna connector's center pins. Ground the shells of both
antenna connectors to the spot where you disconnected the antenna coil.
Tune the radio to 710 KHz and tune for minimum signal. No you have a
deep notch at 710 KHz and you won't have to worry about overloading the
front end with WOR's signal.

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

In message , Roland Stiner
writes
I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

Roland, NK2U



Are you sure that the harmonic is not being produced in your receiver?
Some sort of non-amplifying preselector will confirm.
Ian.
--

Roland Stiner wrote:

I live 2 miles away from WOR 710's transmitter site in NJ. I am receiving
them loudly on thier 5th harmonic on 3.550 MHz. My question is: by how
much does an am broadcaster have to surpress thier hormonics?

Roland, NK2U

Almost certainly it's the radio overloading on 710 and itself producing the harmonic
you hear.

Test it some miles away and it should stop, unlike an actual radiated harmonic.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

Are you sure that the harmonic is not being produced in your receiver?
Some sort of non-amplifying preselector will confirm.

They're there even with the pre-amp off. I do think it might be a front end
overload problem.

Roland

"Receiving them loudly" is rather vague. How many watts are they
transmitting? What kind of antenna pattern? They are probably
operating within specs but overloading the front end of your radio.


S5 at my location. They're a Class A station 50,000 day/night.

Roland

Almost certainly it's the radio overloading on 710 and itself producing
the harmonic
you hear.

Test it some miles away and it should stop, unlike an actual radiated
harmonic.

Thanks, will try that.

Roland