RF Shorts – April 28, 2011
RCA ATSC/ATSC MH Receiver Update
Here's a quick update on the RCA handheld ATSC and ATSC Mobile DTV receiver manufactured by Digital Stream that I reported on last week.
The receiver that I tested was the DMT336R; the model with a built-in battery and FM radio tuner, not the DMT335R, which doesn't include FM radio, and uses AA batteries. However, I would expect the performance of the two receivers to be the same. An adapter is available on the accessory page of the RCAPortableTV.com web site to connect a coax with an “F” connector to the miniature jack on the receiver.
I had the opportunity to test Mobile DTV reception in Chicago, and with the exception of one or two very short dropouts, had reception on the lower level of Michigan Ave. (below ground level!) on the short trip from downtown to WMAQ-TV's studios. Reception didn't disappear until well inside the underground parking lot at the TV station. I initially noticed the same problem in receiving the mobile signals in Chicago as I did in Los Angeles. Unfortunately, after writing my article last week, I found that power cycling the unit didn't always restore reception.
I discovered that by using the “Quick Search” menu item to manually select a channel without Mobile DTV, then going back to the station with Mobile DTV, usually provided reception after a few tries. The problem occurs mainly when the receiver isn’t moving, and this is evidenced by no signal strength indication on the display, even though the ATSC tuner has a strong signal and is able to decode the legacy stream with no problem. Once the receiver locks onto the mobile signal, reception holds even under adverse conditions, as noted earlier.
Early British TV Sells for £17,000
Recently I reported on the planned auction of what was billed as the “oldest working TV”, a Marconi type 702 mirror-lid television first purchased in 1936, (TV Technology’s Technology Editor, James O'Neal, pointed out, this was not the oldest working TV in the world). However, The Daily Mail, in the article They don't make 'em like they used to: 75-year-old WORKING television sells for £17,000 at auction referred to it as “Britain's oldest working television set.” (At the current conversion rate, £17,000 is about $28,000 U.S.) The article said there are more 18th century Stradivarius violins still in circulation than pre-war TVs. The auctioneer's Website has pictures of the TV set, including some of the inside. If the photos were slightly higher in resolution, you could read the color code on the resistors. Some of the components appear--especially the capacitors--to be more modern than those I remember from old sets that I dismantled when I was in high school. Perhaps that's why the set is still working!