It may be as simple as a the electrical height of the tower placing the skywave optimum reception at different distances.
I used to hear 660 in Phoenix in the early 70's with some regularity by nulling XERPM.
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
NYC AM signals
- Thread starter Ai4i
- Start date
It may be as simple as a the electrical height of the tower placing the skywave optimum reception at different distances.
I used to hear 660 in Phoenix in the early 70's with some regularity by nulling XERPM.
Ya' think?
A thought here from the peanut-butter gallery .....
Wouldn't the sole tower have one ground system?
If that's the case, then perhaps .... lemme find the technical term .... perhaps the resonant reflective ceramic matriculation impedances wouldn't match?
Wouldn't the sole tower have one ground system?
If that's the case, then perhaps .... lemme find the technical term .... perhaps the resonant reflective ceramic matriculation impedances wouldn't match?
This is the FCC data.
880, WCBS
Top-Loaded, 207.1 Electrical Degree (195.98 meters) Tower:
Tower: 167.8 Degrees (158.79 meters)
Top Loading: 39.3 Degrees (37.19 meters)
RMS Theoretical: 426.48 mV/meter (per kW) or 3015.67 mV/meter at 50 kW
660, WFAN
Top-Loaded, 155.37 Electrical Degree (196.03 meters) Tower:
Tower: 125.9 Degrees (158.85 meters)
Top Loading: 29.47 Degrees (37.18 meters)
RMS Theoretical: 379.81 mV/meter (per kW) or 2685.66 mV/meter at 50 kW
The data indicates that the antenna system (the tower and ground system) are more efficient at 880kHz than at 660kHz.
880, WCBS
Top-Loaded, 207.1 Electrical Degree (195.98 meters) Tower:
Tower: 167.8 Degrees (158.79 meters)
Top Loading: 39.3 Degrees (37.19 meters)
RMS Theoretical: 426.48 mV/meter (per kW) or 3015.67 mV/meter at 50 kW
660, WFAN
Top-Loaded, 155.37 Electrical Degree (196.03 meters) Tower:
Tower: 125.9 Degrees (158.85 meters)
Top Loading: 29.47 Degrees (37.18 meters)
RMS Theoretical: 379.81 mV/meter (per kW) or 2685.66 mV/meter at 50 kW
The data indicates that the antenna system (the tower and ground system) are more efficient at 880kHz than at 660kHz.
With the top loading, WCBS approximates a 5/8 wavelength tower. I'm not familiar with how top loaded towers behave regarding skywave, but if they are similar to a full vertical, then 880 would have the classic secondary skywave lobe, with a null between the two.
The 660 operation is less than half wave with the top loading, and would have a higher angle of radiation, which would not favor areas at the distance of Texas and the plains states.
Maybe RFry or Schrodingers Cat can de-mystefy this.
Correct, David. Top loading tends to increase the groundwave at the expense of the skywave.
For local coverage, I'm betting that 660 wins (No pun intended).
For local coverage, I'm betting that 660 wins (No pun intended).
Regarding why WOR tried to serve both New York and Philadelphia at one time, WOR's first 50KW transmitter site was much farther south than it is now. I believe it was in Carteret, NJ. At some point, probably in the 70's, the decision was made to have a more competitive signal in New York, and the site was moved to Lyndhurst. The directional antenna was also modified to focus on New York. Before the site move, WOR sounded like a low-powered local station in my hometown of Baltimore during daytime hours.
Yes, WOR was in Carteret NJ. That's about 15 miles closer to Philadelphia than the stations with towers in the New Jersey Meadowlands and closer still than stations in places like The Bronx and Queens. But as said above, WOR moved to the Meadowlands decades ago.
I know that the lower you go on the AM dial, the better your daytime coverage. You could hear 540 in Islip Long Island, when it only had 250 watts in the daytime, in Hartford CT and Princeton NJ. But what happens at night? Skywave doesn't care whether you're at 640 or 1540? Someone above seems to say higher frequencies have better propagation at night.
I know that the lower you go on the AM dial, the better your daytime coverage. You could hear 540 in Islip Long Island, when it only had 250 watts in the daytime, in Hartford CT and Princeton NJ. But what happens at night? Skywave doesn't care whether you're at 640 or 1540? Someone above seems to say higher frequencies have better propagation at night.
R
rbrucecarter5
Guest
Shows how little you folks know me. 35 years ago I was and independent contractor - lending a hand all over the country. My resume was pretty impressive including stations you would recognize. But those days are long past. No more tower climbing, antenna bay installation, transmitter replacements for me. Too old for that. Everybody who mentored me is either dead or long retired - as am I. Some died in a tower crash. I am not going to trot out a dusty resume from the past to impress you. I know what I did.
Someone above? I guess you mean me, and not God! Let me expand this thought:
Yes, 1540 would have better skywaves than 640, but any of the tropical bands would be even better, 120m, 90m, 60m, and the forty-nine meter international band would be still better, followed by forty-one, thirty-one, and twenty-five meters, which is usually around the nighttime MUF (maximum usable frequency).
Your experience is: "lending a hand" Got it. Just so you know; that isn't considered as being a professional broadcast engineer.
You installed antenna bays? What about the rest of the antenna? What sort of transmitter replacement? AM, FM, CB?
And by your posts, including continuing claims that you use an Agilent brand spectrum analyzer to measure field strength, makes it clear we wouldn't be impressed with the reality.
Generally speaking, "antenna bay installation" is something most of us who have actually been involved in broadcast engineering would leave to a rigger.
While we might have done rooftop microwave antenna installs, placed satellite dishes and the like, tower climbing, mounting gin poles and the like is not part of most of the general scope of radio station engineering as that involves a whole different skill set.
Exxon, Valero and Gulf stations?
- Status