skyvalleyradio wrote:Gentlemen - during the months of May, June, July and early August a long-distance form of VHF propagation exists called "Sporadic-E" because it bounces signals in the 20 - 150 mHz range off of the E-layer of the ionosphere. Before such long-distance signal conditions can exist on the FM band, they affect long distance contacts on several ham radio bands - the 12, 10, 6 & sometimes even 2 meter bands. Low-band VHF TV channels from 2 - 6 also experience this form of propagation. Before, the US went all-digital and turned off many low-band VHF TV transmitters, receiving long-distance TV signals on blank low-band channels was common. A few TV DXers use digital cards and high gain antennas to receive the few digital broadcasters that use frequencies below ch 6 TV. Sporadic-E propagation has a typical "first hop" of 900 - 1200 miles and requires next to nothing for an antenna. This would explain why you guys had such clear signals listening on car radios. Sporadic-E propagation can sometimes bounce a 2nd time - even more rarely a 3rd or even 4th time although you will not likely experience this with FM radios with modest antennas. For the 50 mHz (6 meters band) ham band, I use stacked, rotatable high-gain yagi antennas, a medium-powered RF amplifier for more output wattage and morse code which will "punch" through the static with a signal too weak for the human ear to detect a voice. So remember to do a dial scan on your FM radios from time to time throughout the summer. Long distance propagation will first start at the low end - 88 mHz and if it builds, will go right on past 108 mHz. Keep DXin'
Since moving to Edmonton at the beginning of 1975, the only even semi-serious DX I've done was in the late 1980s when I was fortunate enough to have a TV antenna pointing at San Francisco, on a house on a hill 50 km East of Edmonton. The antenna faced that way to reduce interference from a computer controller I had running in my basement at the time. Once the controller was outdated, I turned it off and got some great DX.
I forget the exact number, but I had well over a dozen different TV stations received on Channel 2, plus a few on Channel 4. And even a very likely reception of Sacramento on Channel 3 with local CFRN-TV on the air! Discussing my catches with RadioWest member and well-known DX'er Frank Merrill, he thought the Spanish audio-only I heard once was a rather low powered Mexican he had caught a few times. Which led me to the following thoughts when the disappearance of U.S. analogue TV stations was first discussed:
TV DX must be awful interesting now, paralleling what the FCC comments around 1970 had me thinking back then when the U.S. was going to go it alone and force all AM stations to switch to FM: the absence of U.S. stations would be a DX wonderland. Mexican stations at high noon on AM most of the winter "then" translates to a lot of opportunity to DX Mexican stations on the lower TV channels today.
Nothing on Channel 2 nearby makes it great in Edmonton, but I no longer have any kind of antenna. But what about Vancouver/Seattle? Channel 4 is the lowest channel that looks very interesting, with CBUT on Channel 2 and a Chilliwack repeater on Channel 3. Does skyvalley or anyone else have anything interesting to report?
