Huh. There's only one site on Google that has anything relevant on it, and it's just a sales representative number. It does have a picture of the adapter, and it does have it listed under "cable TV" products.
http://emersonnetworkpower.com/webapp/w ... angId=-1#6" onclick="window.open(this.href);return false;
Have you tried measuring the output with a voltmeter?
Do you have an old TV junk VCR you don't mind potentially messing the tuner up on to try and see if it does anything?
Maybe it's supposed to supply boost power to an amplified antenna. We have one of those little square DTV/UHF antennas and it has a small power adapter that connects to the coax line. Maybe that one gets daisy-chained with the antenna it came with (AC adapter -> antenna -> TV)