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AM Frequency of the Week - 1170 kHz

30 miles south of Indianapolis:

Daytime, WLBH Mattoon,IL which is semi-frequently off the air. When that happens, a very weak WDFB Junction City,KY appears.

Night...it's a mess.

Near sunrise, KFAQ Tulsa,OK is not uncommon.

Worth noting that when I grew up in Cincinnati, WWVA dominated the channel most every night. I'm now 80 miles west of there and have never heard it here.
 
Near Wellsville, NY

Days: nothing
Nights: WWVA (Wall to wall, tree top tall) :D Thankfully WHAM skips over me nights so no I-noise here!
 
Hmm... from El Cajon / La Mesa, CA, near 32°45'40"N 116°56'50"W ... 1170 kHz ...

Well, there is KCBQ San Diego on the frequency ... and it is probably NOT quite exactly what you would call a weak signal! ;) (I'd guess it'd probably be about an S-8 or maybe an S-9 or so, allllmooost beginning to approach pest territory, right? ;) )

The other day in the mid afternoon, I took my PL-606 about 0.1 mile up the street, and recorded a few minutes of their signal, including the long version of the TOH ID. (Not included in that clip, aired a minute before the one in the clip (immediately before a commercial and after the music bed from the talk show faded out) was a short ID, something like "KCBQ San Diego, a division of Salem Communications - on the NASDAQ as SALM.")

KCBQ is so strong at my house, that even on my Tecsun PL-606 (which I thought was supposed to be immune to intermods and things like that), I can hear them in the background of 910 KECR under their unmodulated carrier - examples in clip #1, clip #2 and clip #3.
In fact, they can even be fairly easily heard using only a simple crystal set and Select-A-Tenna next to a utility ground wire on a power pole in my front yard, they are so strong!

Even as strong as their signal is at my house, though, it IS possible to null them out almost completely, even on their 50kW daytime pattern.

KCBQ does drop to 2.9 kW at night, but it is still quite the pest here. I have been able to hear KLOK San Jose under them, though, with considerable difficulty (except for about 10 seconds each morning and 10 seconds each evening when it's a little easier).


If you thought it was strong at my house, though .... wait till you try to DX anything under them from here, about 9.3 miles north of my house! (A second video is here recorded at the same place.) Am I the only one on this board that has had a signal THAT strong on my Tecsun DSP radio? ;) I would guess that even if you might not call the signal at my house a pest, this probably would be a somewhat good candidate. :)
There, it's even so strong that their harmonics can be heard on the FM band (!!) on my PL-380 and PL-606. (A photo of the PL-380 receiving them on another FM harmonic is here. It will even overload a crystal set!! In fact, at that location, you don't even NEED a radio to hear them. I recorded this with ONLY my Zoom H2n audio recorder (which has no radio function built in) and a few-foot audio cable plugged into the headphone jack!

BTW I wonder if R. Fry. has some estimated idea what approximate field intensity would be required to overload a crystal set, or to produce those extreme overload effects in the Tecsun DSP radio ... WITHOUT any type of antenna connected to the radio whatsoever (not even a ferrite bar, just at most the short lead stub on the diode on the xtal radio or the antenna input pin on the DSP chip)?
Also does anyone have an idea how to prevent my H2n from picking up KCBQ's signal when it's that strong, yet have my radio get the full force? (I'm wondering if in some parts of a couple of those videos, some of the audio was coming through my audio recorder and not the radio. I'd like to be able to eliminate that without reducing the station's received signal strength.)


They do have what to me is a very interesting pattern change, though.

At night, they will shut off their 50 kW for about 1/8 second or so, then bring up their 2.9 kW night transmitter. (If you blink you'd miss it.) Then, several seconds later, they go off completely for about 10 or so seconds, then come back on with their 2.9 kW.
Here is a video recorded from about 3.2 km SE of their TX site at the time of their day/night pattern change. Most of the recording is on 1160, but you can hear the spots where KCBQ drops power, then cuts out completely, based on the blocking being different, and the signal indicator dropping a couple times. (The beginning and end of the recording does have KCBQ.)

Their daytime change is basically the opposite sequence. They start off by shutting their 2.9 kW night transmitter off completely for about 10 seconds, then turn that same one back on. Then several seconds later, it goes off and a split fraction of a second later the 50kW comes on.
I recorded this video at their night/day change with my PL-606 about a few hundred feet west of where I recorded the video linked earlier that was recorded up the street from my house. KCBQ even at night is still fairly strong in that recording. You can hear where they go off the air, but due to IBOC noise or something (I tentatively blame KSL) nothing else can be ID'd in that clip on 1170 while it's off. (Right as they come back on after the several seconds of being off the air, there is about a second or so of subdued but somewhat intelligible audio. I'm not sure if that's KCBQ's audio coming through while the transmitter is still warming up or something, or if that could be crosstalk from 1130 KSDO, whose 10kW is about 6 miles to the north.)


So does anyone else have locals that are as strong as or stronger than that? ;) (Especially on 1170, as that's the frequency for this topic.)
 
pianoplayer88key said:
Hmm... from El Cajon / La Mesa, CA, near 32°45'40"N 116°56'50"W ... 1170 kHz ... BTW I wonder if R. Fry. has some estimated idea what approximate field intensity would be required to overload a crystal set, or to produce those extreme overload effects in the Tecsun DSP radio ...

No, but looking at KCBQ's day pattern and fields, they should be producing a ground wave of about 146 mV/m at the coordinates quoted above (earth = 8 mS/m).

Also note that S9 on many communications receivers is calibrated for 50 µV across its antenna input terminals.
 
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