Around 7:30 PM today, I heard a news broadcaster on 104.5, narrated by a man with a British sounding accent. The station broadcast in mono. For the entire time that I was listening, a story was running about the economy of Brazil. As I approached the Sylvan hills, the signal was wiped out by intermod, and when I got far enough away for the interference to disappear, the mystery 104.5 was also gone.

What was I hearing? A search of radio-locator does not show any stations or translators within a 300 mile radius that would be likely to carry BBC World Service or any other long-form newscasts.

KOPB-FM skip. You were close to the transmitter site.

Speaking of mystery signals, there's a pirate up in my neck of the woods that's carrying a stereo feed of WCBS-FM from NY!

Imagine my surprise on the way home from work last night to hear WCBS jingles and news updates!

My first suspicion was that the 104.5 could somehow be television audio. I quickly dismissed that because the signal was just as loud as other FM broadcast signals. I didn't think to check 91.5 to see if it was running the same program. Since I suspect that this could be a pirate (or an overpowered "Part 15" station), I'm keeping the exact location vague. If some guy is rebroadcasting BBC World service for himself and a few of his neighbors, I don't want to get that guy in trouble.

Could have been some ducting from Canada, perhaps. Last Monday afternoon, while monitoring KQAC 88.1 (Gleneden Beach), I was treated to about 20 minutes of good solid jazz, and a pledge drive from K-jazz (KKJZ) from Long Beach California. Stable long-haul conditions can exist this time of year...it sounded like a local! Good first DX catch for a Sony XDR-F1HD that had just arrived hours before.

>>KQAC 88.1 (Gleneden Beach)

In Salem I am now picking them up over the 88.1 in Lebanon.

CBC Radio 1 stations broadcast in mono, so that is a definite possibility.

heres one for you....KQEN - am 1240 in Roseburg got a fax this morning from someone who picked us up in Virginia while driving to work this morning.....loud and clear....all 5 lites on his radio lit up.....sounded like a local station....quite the "skip"

It IS a local station! No kidding, that's amazing! I didn't think that would happen on a graveyard frequency.

No kidding! That's one kilowatt that went a LOOOOOONG way.

We are flying a rep out to sell ads....(!)

The plot thickens on the mystery 104.5. Today, I went to the part of town where I last heard this station (I do volunteer work on Mondays in that area). I got out there around 6:15 PM, and I heard a dead carrier on 104.5. The next time that I listened was on the way home, shortly after 9:00 PM. I heard PBS television audio, with "American Experience." The modulation levels seemed low this time.

The next time that I'm over there, I need to take one or more extra radios in order to try to eliminate the possibility that I'm hearing channel 10 audio due, for instance, to a harmonic of the local oscillator in my car radio.

So it is not a rare skip or ducting (you heard it again in the same place), not a real pirate (risking discovery broadcasting dead air rather than turning off the transmitter when programming is finished), I don't think it is channel 10 (they usually don't broadcast dead air)... Perhaps somebody with a powerful set of cordless headphones tied to their stereo?
Do you hear Mix 104.5 The Dalles while driving around?

I did hear the mystery station fighting with a music station that might have been Mix 104.5. I didn't hear any IDs from the music station in the brief time I was listening. On the off chance that it is a pirate or a "neighborhood" station, it must be running very low power, likely 1 watt or less because I could only hear it for about 1 1/2 miles or so. I only heard the dead air for about 5 minutes or so, so is possible that whatever program source they were playing (Internet stream? mp3s? CD?) died for some reason.

Some weeks ago, while visiting Colorado, a former college classmate demonstrated for me how far a 10 mW FM broadcast band signal could be heard, if one is willing to put up with a very weak signal. This is why I could easily picture a 0.5-1W transmitter, like those that Ramsey sells, being the source of the mystery 104.5 MHz signal.

Check out KOPB-TV's Broadcast Auxiliary listing at the bottom of the page.

http://www.recnet.com/cdbs/fmq.php?call=KOPB-TV&city=&state=&country=US

"This is why I could easily picture a 0.5-1W transmitter, like those that Ramsey sells, being the source of the mystery 104.5 MHz signal."

There are several people that I know about in Portland with those,or similar small kits.
I've got one myself. (I'm not on 104.5 though.)

The Belmont/Hawthorne area seemed to be a sort of "hot spot" a year or two ago.I'd drive around and hear several different signals.

On Saturday afternoon, I did a little more hunting around. The mystery station was only transmitting a very faint whine at this time. I brought a Radio Shack DX-390, which has a 7-bar signal strength meter.

In the first location that I tried getting out of the car and walking around with the DX-390, all that I could hear on 104.5 was interference from local stations overloading the radio.

I drove about 1/4 mile down the road, where the 104.5 signal sounded a little more solid on the car radio. I got out and walked around. In this location, multipath caused the signal strength display to go all the way to 7 bars if I stood in the right place. If I walked into a place where the signal cancelled, the interference took over.

I then drove to a point about 1 mile away. On this drive, I noticed that the signal became more stable, and I also noticed that I was near a school campus. Aha--this must be a campus station, I thought. However, as I reached the campus, the signal started getting weaker, and there was more multipath. A walk-around with the DX-390 showed that the signal went from 7 bars to being buried in noise, depending on where I stood. My best guess is that the transmitter is located in a residence somewhere between points #2 and #3 in my little hunt.

This evening, I picked up 104.5 again, but there was no audio, just a faint whine.

Tuesday evening, I heard programming once again on the mystery 104.5 station. The first time that I tuned in, around 6:30 PM, Blues music was playing. It sounded like the program source was segueing out of some of the songs halfway through the song. Thus, this program source is something a bit more sophisticated than a CD changer. The second time I tuned in was around 8:30 PM. What was now playing sounded like the audio of some documentary TV show. The first segment was on a luxury hotel; the second was about the Stanley Steamer; the final one that I heard before losing the signal was about the Grand Canyon park. I took a different route this time, and I was able to get the signal for a few miles, with spotty reception. I suspect that the transmitter power is approximately 1-5 Watts, with the antenna at a fairly low elevation.

It's gotta be a TV station audio.

Sounds like someone has an FM modulator hooked up to their home PC... Maybe they live high on a hill... maybe they have broadband and watch streaming video... then play some tunes they happen to like.. all intended to be picked up on their home stereo... or around their neighborhood.

I tried one of these and it went about a block around my place with no special antenna setup.