AM Frequency of the Week: 910

Now for the next several weeks we go to a series of what used to be known as "regional" channels. First of which is 910....

DAY: At my location northwest of Chicago, it's a very, very weak WSUI from Iowa City. For me, "The Big Pig" is only audible on my Superadio-2 outside in a noise-free area of my backyard or on a good car radio in a similarly open area.

NIGHT: Usually a mix of unidentifiable signals. WSUI sometimes surfaces, as does WFDF.

Sunrise-Sunset (Retro): I used to hear KLCN from Blytheville, Arkansas on a fairly regular basis on 5kw ND day pattern. But, it's probably been 15 years since I last snagged them.

In the near north Chicago suburbs during the day I hear a weak WGTO Cassopolis, Mi with classic hits including some good 60s oldies. At night it's a mixture of stuff with sometimes WFDF.

Retro: Back in the day I used to hear WSBA at night with good top 40 music, but that was quite awhile ago.

In southern Colorado daytime it's a fairly weak KPOF Denver CO, which I'm guessing is one of the old-line occupants on the channel given its 1 kW ND pattern at night.

Retro: I heard myself talk on the "Big Pig" as a student announcer in the late 80s at the State University of Iowa. WSUI has rather unfortunate calls. We were coached by the permanent staff on how to says those calls. "Double-yoo Ess Yoo Eye" with spaces, not "Double-yooEsShoeEye." Today, I doubt there are many student announcers left with WSUI being part of the previously unthinkable Iowa Public Radio, a consortium of the Iowa Regent schools including Iowa State's WOI and Northern Iowa's KUNI.

Escaped the Big Flood of '93 in Des Moines that swamped the Water Works by visiting a friend's summer cabin in Bayfield WI. WSUI was easily heard there at night, no surprise with the night pattern shooting north.

In the 70s, WSUI was the only signal in Iowa that had that irritating background hetrodyne whistle, or I think it was a hetrodyne whistle. Approaching 910 on an analog tuner from 900, you were greeted with a very pigh pitched tone that would drop in frequency until it was a very low hum at the center of the 910 kHz channel. Tuning up from 910, the hum would quickly change back to whistle and dog-whistle.

@joebtsflk1.... Sidebar point. Iowa '93 flood brings back memories of my daughter going to summer school and one of two girls sharing a room in a frat house (Accacia House). I was the ultimate nervous dad, especially when they were surrounded on all sides by floodwaters for several days and couldn't escape! Fortunately they had ample supplies of food...and beer. (As I discovered when I arrived after the waters receded and I was "greeted" by two dumpsters overflowing with beer cans!)

But actually, she was fine, had what turned out to be a great experience, and ultimately went on to get her masters degree and a career in universty-level teaching and administration...including 15 years based in London and the United Arab Emerates. (She's now in Los Angeles)

Back on topic.... I never heard the "notorious" het that plagues the 910 channel. In the case of my own time in Iowa, where I was 45 miles south of Iowa City WSUI had a good signal night and day. The night signal, aimed north, was obviously weaker, but still good and all alone.

I've heard the het on 2 stations on 910, first was CKDQ Drumheller Alberta, known as Q91. It was present on every radio I had and it was a local signal to Calgary, as the transmitter was and is 20 miles east of town on Highway 1. It wasn't until I got an AM stereo tuner and a digital tuner that the het disappeared. I've also heard it on WSUI when I was in Iowa. I've heard that one of the reason KIXI Seattle moved to 880 from 910 was because they were plagued by the het, known locally as the KIXI Whistle.

Nothing day or night here in suburban Columbus. Local WMNI is next door at 920, but they are so directional to the north that they have a subpar signal day and night across much of the metro area, meaning there's very little slop in a lot of areas.

I never heard WSUI called the Big Pig (although it is a local station in my area)! However, I have often thought it's funny that the same letters are on the FM classical station, KSUI. Classical music is dignified, while pigs, not so much.

We used to hear the het whistle on WSUI at night in Cedar Rapids. I actually listened to them at night sometimes because I was just that kind of kid. Public radio, BBC, etc.

Stupid question: What was the cause of that whistle, a station off frequency somewhere, or something in the design of people's radios?

Here on the Gulf of Mexico in Alabama I can't recall hearing anything on 910 day or not.

Warminster PA(Philly 'burbs):

Daytime: a very weak signal from either WSBA York PA or WRKL New Rochelle NY.
Night: mess of stations, including WSBA and WRKL.

Re: cause of whistle... The intermediate frequency of most AM superhet receivers is 455 KHZ. The local oscillator in the receiver usually operates at desired frequency frequency minus 455khz ish. When tuned to 910 the local oscillator is tuned to 455 KHZ (910-455=455). The second harmonic of the LO beats with the desired frequency of 910.

That HET is caused by the I.F. frequency in the radio. 455 Khz is a very common IF, and if you double that, you get 910. I remember this, as my dad was a big fan of then country, KNEW 910 in the SF bay area. All of our radios had the HET problem. Very hard to zero beat it, as the radios weren't perfectly stable. A well built digital PLL tuner would stay perfectly zeroed, whereas an analog one would not.

Hope that helps!

df

tomservo said:

Stupid question: What was the cause of that whistle, a station off frequency somewhere, or something in the design of people's radios?

Here on the Gulf of Mexico in Alabama I can't recall hearing anything on 910 day or not.

Click to expand...

910 days - usually nothing

Night - a mix of stuff, usually KMTT Vancouver WA (Sports) is on top, mixing with CKDQ Drumheller AB (Country) and KKSF Oakland (ESPN Deportes). KWDZ Salt Lake City used to pop up in the jumble until they went silent. Occasionally at sunrise I'll get KCJB Minot, ND (Country). Other stations logged include XEAO Mexicali (Regional Mexican); KPOF Denver (Christian) and KGME Phoenix (Fox Sports).

Wanted on 910?
KURY Brookings OR, one of my most-wanted in general. This station, running Adult Standards, can't seem to make it at either sunrise OR sunset. It's 1KW. Log this station and I will have logged all 94 Oregon AMs.
KBLG Billings (ESPN), but needs a local ID at sunrise. They are flea power at night but run 1KW day.
KOXR Oxnard (La Mexicana), should be possible during Au when KKSF is weak.
KECR El Cajon (Family Radio), maybe possible at sunrise or sunset.

910 here is local WTMZ with a sports format. It has been sports for most of the last two decades. For a while back in the early 2000s, it was a good adult standards format. The signal is weaker than a couple of the other AMs because it is based from North Charleston, and it sometimes has nulls on James Island, especially at night.

Spartanburg, SC comes in under them frequently, especially during critical hours.

vacuum tube said:

Re: cause of whistle... The intermediate frequency of most AM superhet receivers is 455 KHZ. The local oscillator in the receiver usually operates at desired frequency frequency minus 455khz ish. When tuned to 910 the local oscillator is tuned to 455 KHZ (910-455=455). The second harmonic of the LO beats with the desired frequency of 910.

Click to expand...

jammerdave said:

That HET is caused by the I.F. frequency in the radio. 455 Khz is a very common IF, and if you double that, you get 910. I remember this, as my dad was a big fan of then country, KNEW 910 in the SF bay area. All of our radios had the HET problem. Very hard to zero beat it, as the radios weren't perfectly stable. A well built digital PLL tuner would stay perfectly zeroed, whereas an analog one would not.

Hope that helps!

df

Click to expand...

Thanks guys, that makes a lot of sense. I guess I've grown up in the era of mostly PLL tuned radios and also never anywhere where there was a 910 kHz AM to listen to, so I never encountered the issue.

Daytime here is a fairly strong semi-local KNAF in Fredericksburg.

At night Guadalupe Radio Network station KATH in Frisco, TX, has the most predominant signal, but it's not strong/steady and can be nulled. In that null it's a mix of stations popping in and out, most usually a weak KNAF and occasionally a weaker KKBE "The Beat" in Roswell, NM, or KRIO "Radio Esperanza" in McAllen, TX. Also, I'll sometimes hear a weak-moderate Radio Metropolitana in Cuba. One time a couple of winters ago I heard WUBR "CBS Sports Radio" in Baton Rouge briefly.

At sunrise both KKBE and KRIO are noticeably stronger until they're taken out when KNAF goes to day power.

I worked at WPTX, 920 KHz in Lexington Park, Maryland, while in the Navy in the Mid '70's.
We had that whistle a lot, too...due to the IF frequency.
That's one of the reasons I always wanted a McKay-Dymek tuner...for the 10K "Whistle Filter".