Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old April 11th 05, 03:37 AM
Roland Stiner
 
Posts: n/a
Default 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



  #2   Report Post  
Old April 12th 05, 01:21 AM
Charlie
 
Posts: n/a
Default

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

  #3   Report Post  
Old April 12th 05, 01:21 AM
Bill Blomgren
 
Posts: n/a
Default

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.)

  #4   Report Post  
Old April 12th 05, 01:21 AM
Doug Smith W9WI
 
Posts: n/a
Default

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

  #5   Report Post  
Old April 12th 05, 01:21 AM
Michael A. Terrell
 
Posts: n/a
Default

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



  #6   Report Post  
Old April 12th 05, 01:21 AM
Ian Jackson
 
Posts: n/a
Default

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.
--



  #7   Report Post  
Old April 12th 05, 01:21 AM
Ron Hardin
 
Posts: n/a
Default

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.

  #8   Report Post  
Old April 18th 05, 10:47 PM
Roland Stiner
 
Posts: n/a
Default

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



  #9   Report Post  
Old April 18th 05, 10:47 PM
Roland Stiner
 
Posts: n/a
Default

"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



  #10   Report Post  
Old April 18th 05, 10:47 PM
Roland Stiner
 
Posts: n/a
Default

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



Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Extracting the 5th Harmonic Paul Burridge Homebrew 324 March 28th 04 10:34 PM
A Simple Harmonic Generator. Reg Edwards Antenna 12 March 23rd 04 09:16 AM
A Simple Harmonic Generator. Reg Edwards Homebrew 6 March 17th 04 08:47 PM
A Simple Harmonic Generator. Reg Edwards Homebrew 0 March 16th 04 11:31 PM
Extracting the 5th Harmonic - revised design Paul Burridge Homebrew 0 March 14th 04 03:32 PM


All times are GMT +1. The time now is 06:33 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017