My Most Interesting BCB DX Catch Ever

[Ai4i]

I am into driving around the nulls of highly directional stations to find their weakest directions,
listening for mixture products where two AM stations share the same towers, and of course, a third thing.
I was crossing a bridge near downtown Sarasota when a relatively interference-free but slightly distorted station popped in on 1640.
Who were they and why did someone just mention area code 813?
As it turns out, that bridge is about forty miles from and smack dab in the middle of one of a fifty-kilowatt station on 820's main lobes.
So there I was, listening to that station's second harmonic in the day from so far that they are barely listenable at night.
I have heard many second and third harmonics, but never that far.

Any similar experiences from the peanut gallery?

 

[rfry]

Might it be that the steel framework of the bridge has some poorly bonded joints acting as (non-linear) sources for that harmonic generation?

Such harmonic fields could be relatively high in the near-fields of their generators, but would fade away quickly at greater distances.

 

[Steve Green NEPA]

@ a141 : Wouldn't 1640 be the first harmonic, not the second?
Lol -- no offense, of course. It's just that I got corrected on that myself once when I told of driving past 77 WABC's tower and hearing them on 1540.

Perhaps that bridge was lasered right in-line with -- zero-zero you might say -- one those main 820 lobes that you mentioned?

* * * * * * *

For a few years back in the late Sixties on Long Island, 1290 WGLI put a weaker yet steady signal on 1160, of all places. Car radio, home receiver : made no difference. The 1160 'spur', if you will, also embraced the same directional characteristics of the parent signal.
The now-dark WGLI sent 5000 daytime watts from their three sticks southeast, through the COL, and had listeners reported in Bermuda. WGLI sent a small tongue, perhaps a default fragment of signal, northwest. At night in some spots, when WGLI kept the same pattern but dropped to 1000 watts, there were places in the nulls where you could see their three blinking towers and enjoy (if that's the word) the station being splashed on horribly by neighbouring WADO NYC on 1280.

Anyway, we never got to determine why WGLI 1290 was such a faithful catch on 1160 as well. I'm thinking that the actual spur might've been more on like 1157 or 1158. There was no mathematical solution we could figure. We tried figring things like 2 times 455 minus whatever. No luck. Unlike the Meadowlands' phalanx of towers, Long Island only had two full-time AM stations. WGLI was one ; WGBB Freeport 1240 was the other. I doubt they 'beat' off each other ; they were 20 miles apart.

Good catch, though, a141! As they say, nice things happen to those who DX.

 

[Ai4i]

Might it be that the steel framework of the bridge has some poorly bonded joints acting as (non-linear) sources for that harmonic generation?
Such harmonic fields could be relatively high in the near-fields of their generators, but would fade away quickly at greater distances.

I do not know how the signal was produced, just that I heard it and will listen again.
In Miami, I used to hear a 5Kw station on 560, on 1120, for about eight miles,
from the Miami Herald building to Miami-Dade community college (then, junior college) north campus.

Good catch, though, a141! As they say, nice things happen to those who DX.

Thanks!
My first radio job was babysitting an AM transmitter where I calibrated my personal analog(ue) general coverage shortwave receiver by the station's harmonics all the way up to 30MHz.
Certainly, the math would have been easier if the station had been on 1000!
BTW, every Potomac FIM that I ever used, intentionally included a band that went up to the third harmonic of the top of the BCB. It was 4.8MHz back then.

As for your 1290 on 1160, I wonder if anything on 1420 might have been lurking nearby in the dark?
As a child, I could never figure out why I was hearing a 1550 on 1430, oblivious to the 1490 just a few blocks from where I lived

 

[Steve Green NEPA]

I forgot to mention, a141 and RFry -- that WGLI '1160' signal also was there at night.

Fwiw: Here's your 820 50,000 watt torch:

https://radio-locator.com/cgi-bin/pat?call=WWBA&service=AM&status=L&hours=D

 

[Ai4i]

Thanks,
By looking at their FCC pattern shape,
they must be putting nearly the most amount of signal that is possible with only two sticks.
Look at what they do up near Talahassee.
BTW...I believe the the primary signal is the first harmonic.
If it were not, than we would have to subtract one from any references to harmonics.