Monday, October 08, 2007

Deaf Ears.

I mentioned in a recent post my nostalgic revisting of shortwave radio. After that I dug out my old receiver and have been taking the occasional listen, such as tonight. But tonight is not a good night to tune the bands. Propagation is terrible right now, so there is little to hear. We're at the low point of the sunspot cycle, and at such times shortwave radio propagation is at it's weakest, and tonight reflects that. Unlike local AM and FM broadcasts shortwave broadcasts, even from the most powerful transmitters aimed directly at you, are not guarenteed listening. You can turn on a familiar frequency at the right time and hear nothing. I wonder how many receivers have been returned over the years by newcomers who didn't realise this and thought their new radios were broken.

I switched to the longwave band, and did hear what sounded like voices. But it soon became obvious this was a mixing product, a false signal created by two strong signals mixing in the receiver's circuitry. After all local talk show host John Gormley isn't heard on longwave, and it would be a miracle to hear a broadcast station from those parts of the world that do have longwave broadcasting on the ferrite antenna in a shortwave portable in the middle of North America. In North America longwave is limited to navigation beacons.

My radio is a circa 1991 example of the Sangean ATS803a. This receiver was one of the most popular units of the late '80s and early '90s due to its reasonable price to performance ratio. Not only was it sold under the Sangean name but also as the Radio Shack Realistic DX440 and several other lesser known names. I remember reading at one point the suggestion that the '803a, and its predecessor the '803 were based on Sony's ICF 2001. You can read one take on the '803a here.

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