In article ,
Jimw wrote:

On Wed, 7 Jan 2009 18:33:09 -0500, "Ralph Mowery"
wrote:


"David Nebenzahl" wrote in message
rs.com...
On 1/7/2009 1:16 PM Jimw spake thus:

Please post which converter yoiu have and rate it. Are yoiu
satisfied, or dissatisfied? What are it's pros and cons? And in
particular, how well does it perform in a fringe area?

Zenith DTT901. Satisfied; I give it a 7 out of 10.


That is the one I picked up to play with. I am a ways off from the stations
and I hooked it up to a ham antenna that is made for 145 Mhz. that is only
up about 20 feet. Picked up 22 stations in the auto tune mode. A much
higher antenna at 60 feet gave me 29 stations. The antennas are not even
made for regular TV reception. I won't talk about the quality as I only had
it hooked up to an old 16 inch TV. Think it was about $ 60 at Circuit City
before the $ 40 discount card.


I'm surprised it worked at all on a ham antenna. I know the
wavelength affects the reception, and a half wave antenna is half the
length, etc. What is the actual frequency band for DTV, and how does
that compare to the 145Mhz ?

According to the research I've done, other than "low power" stations
(and I still haven't found a satisfactory definition for what makes a
station "low power" - I imagine if I were interested enough to root
through the FCC legalese and tech stuff, I could find it, but I'm not
motivated enough to bother) after the switch, broadcast TV is going to
exist only on the frequencies that now correspond to UHF channels 14
through 51. Which means that for "proper" reception, the range the
antenna needs to be useful on is 470-698MHz. Expecting any kind of
decent performance at all out of a ham antenna tuned for 145MHz on TV
frequencies is... Well, putting it as kindly as possible, just short of
utterly insane. Quite literally, you'd get better performance by cutting
off a chunk of co-ax cable and stripping a bit more than 4 inches (VERY
approximate number - Exact length can be calculated from online
information) of the braid off one end to make a quarter-wave "wick"
antenna before plugging the other end into your TV/converter box.


By the way, are there any decent antenna amplifiers for DTV, or does a
person just use the standard UHF VHF amps they always sold?

Since you'd be working on standard UHF frequencies, a standard UHF amp
should work just fine, but make sure you locate it as close as possible,
electrically, to the antenna's feedpoint to minimize the inevitable RF
"crunge" the rest of your feedline is going to add to the mix. You want
to amplify signal, not noise, doncha know

--
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