Jonathan Takiff: Ch. 6 where are you? Signal sleuths solve a mystery

THE GIZMO: Fine-tuning HDTV reception.

HOUSE CALLS: One of the developers of the digital TV broadcasting standard made a house call yesterday. Formerly an engineer with Zenith, now with the broadcast consulting firm Meintel, Sgrignoli & Wallace, Gary Sgrignoli showed up at my Queen Village house with partner David Meintel and a truck full of gear topped with a fancy antenna that soared 30 feet skyward.

Also knocking at the front door was WPVI-TV transmission engineer Tom Cullen.

Their mission? To sleuth out why I couldn't receive WPVI's (ABC-6) newly relocated digital channels - or those of WHYY-TV (PBS 12) - even with a newly installed rooftop antenna.

Yeah, it's great to be the Gizmo Guy, though the TV stations are offering help for everybody else, too. So are sites like antennaweb.org.

RETURN FOR REGROOVING: WPVI was innundated with calls last month when it shut off its analog Channel 6 signal and relocated its digital signal (previously at a low-power UHF frequency) to the vacated, VHF-6 slot.

WHYY also moved its digital signal from a temporary UHF slot to its old VHF location, Channel 12, and likewise took a ton of "we can't get your channel anymore" calls, engineering VP Bill Webber shared. "Some people were suggesting it was a Comcast-backed plot to get people to switch from over-the-air TV reception to cable." And in fact, Comcast has benefited from the digital transition, picking up almost a half-million new subscribers nationwide.

Rescanning their new digital TVs or tuner boxes solved most viewers' local reception issues. An emergency boost in signal strength also helped WPVI.

But what 6 and 12 couldn't fully deal with right away was the fact that VHF digital signals don't pass easily through window glass and metal screens, so they aren't received as readily with indoor antennas as UHF signals are. Also, VHF signals don't bounce nicely around tall buildings.

OK, so all that explained why I still couldn't get 6 and 12 with rabbit ears at my house south of Center City's high rises and, to the north, the big TV antenna farm in Roxborough. But I also drew a blank on 6 and 12 with set-top boxes and digital TVs attached to a rooftop antenna.

So I called on electrician buddy John Siemiarowski to help me install first one and then (for comparison's sake) a second new VHF/UHF antenna on top of the house's rooftop mast.

The first install was a wild-looking metal basket with plastic loop de loops, a ClearStream C4 from AntennasDirect.com ($149) that's billed as "long range" and required a fair amount of assembly.

The second was a traditional, small-stick UHF/VHF/FM antenna from the familiar brand Channel Master. The CM2001 is a now-discontinued, medium-range model that I found online for a mere $20. Out of the box, it opened up as easy as an umbrella.

Nice.

The antennas helped my TVs scan in 30 digital UHF channels with high-def pictures even sharper, in some cases, than those delivered from satellite and cable TV sources. I also pulled in some extra channels pay TV doesn't bother to carry.

But even with those new antennas, 6 and 12 remained out of reach. The plot sickened.

TRIAL AND ERROR: "With digital, it's an all or nothing kind of thing," explained WPVI's Cullen. "Just a decibel or two more of signal gain can get you over the top, so the blank screen suddenly turns into beautiful pictures."

After extensive outdoor and indoor tests, the guys from MSW determined that there was sufficent signal available in my neighborhood ("though interfered with by a powerful FM station," WMMR), so that I should be getting decent reception of WPVI and WHYY with an outdoor antenna.

The tech sleuths then started picking apart the pieces of my system, creating a more direct line from the rooftop antenna to the TV. Finally, they took out a piece of the powered antenna rotor that had been installed years ago as part of a prior, UHF-only antenna system.

Ka-pow! WPVI's signal suddenly appeared on their scope screen.

"There's a signal gapping problem in the connector cable or the rotor," declared Sgrignoli. So why hadn't it messed up all the channels? "A higher frequency UHF signal will jump across a short better than a VHF signal will. Bring in a new line - preferably RG-6 quad shield cable - directly from the roof antenna, by-passing the rotor and you'll get even better reception from every channel."

Case closed! *

E-mail Jonathan Takiff at takiffj@phillynews.com.