San Francisco, CA - OTA - Page 104

Turbo--

Yes input-stage tuner (or even antenna amplifier) overloading is a possibility. I suspect that the 100' separation is recommended to ensure that you don't get feedback around the two amplifiers that sets up oscillation. I also think that you're most likely correct that the inside box is simply a dc power supply for the mast-mounted amplifier. But if there's a gain adjustment there may be two stages of amplifier, one inside and one on the mast, to achieve it. That would also rule out any sort of splitter between the two boxes. If the inside box is just a power supply, you can use a splitter if you get one that has a dc path through it. There are special models with markings indicating which leg is dc coupled.

Has anyone try the new CM 4220 yet?
http://www.pctinternational.com/chan...0612/4220.html

I'm in San Jose near Milpitas and wonder if it can receive all the channels.

I like it as I can mount it on an old satelite post I still have on the roof with the cables already ran.

When we say "overload", are we talking about damage?

The literature makes it sound like it is a 30 dB gain amplifier, and then an up to 10 dB variable attentuator at the indoor box.

Input stage amplifier overloading isn't likely to cause equipment damage, but it is likely to cause reception problems of one sort or another.

It won't be as good for either high-band VHF reception or multipath signal rejection as is the 8-bay version.

I've lost channel 11-1 (HD KNTV-NBC) since just after the holidays. I have DirecTV and using an HR10. Seems to get plenty of signal, just no picture. Any idea? Antenna is the one they install by default. It worked for 2 years before this sudden failure. All my other OTA HD channels come in fine.

Did you check to make sure that the antenna didn't get moved by the recent high winds?

Yep. And every other channel comes in fine, same as before.

Hmmm, all my signal strengths do look lower than before. Any chance anyone has a 40' ladder I could borrow? That's what it takes to get at my antenna

So, the DC coupled leg is the one you want going to the amp at the mast, and the other leg blocks the DC from going to the other connected devices? I'm-a gonna have to hunt for one of them there thingies. Can't say I've every seen one at a Wally Mart, or such.

Thanks, any recommendation for a smaller antenna than the 8-bay? I need a smaller one that can be easy to mount. Can a 4221 or 4228 be mounted the same way, on the DBS post?

I have an indoor RCA amped one and it's not that great, worst than my rabbit ears one.

Thanks

I am using a 4221 with great results in San Jose. I think you can mount a 4221 on a DBS post.

The point is that the smaller the antenna, the less well it can couple to VHF waves. The "unadvertised" VHF performance of the 4228 has everything to do with the fact that its multiple UHF sections make it bigger overall. This also gives it somewhat more directionality (and therefore m.p. rejection ability). You may find that the 2-bay antenna is adequate for your situation.

I've run into a two-bit snafu. Raising the antenna 7 feet, I want to add another set of three guy wires. Seems that Radio Shack will sell you a $20 mast, and all the guy wire you may need, but in their infinite wisdom, they have discontinued carrying the $1.99 guy ring collar that you need to attach their guy wire to their mast! Radio Shack's brilliance continues to amaze me. I remember when Radio Shack was your one-stop electronics shopping spot. These days, whenever I walk into a RS, it looks like they are going out of business, and if you want a two-bit part that you used to just walk in and purchase, now you have to order it, pay $6 for shipping ... and then wait to return to pick it up.

Anyway, enough sour-puss. Where can I find one of these guy rings, or some way to securely attach the three guy wires to the mast? The ring simply slides down the mast, has three attachment holes spaced 120 degrees apart, and is secured with a clamp. I thought of using an aircraft calmp and three links from a chain, but not sure I trust the clamp. Any ideas or leads? Thanks.

Back to Fry's?

Ya know, after all my whining, as soon as I shut the computer down, I realized that I had forgotten to add that I had also looked for the guy ring collar at Fry's, Home Depot, Lowes, Orchard Supply Hardware, and True Value Hardware!

I live in the North Beach section in San Francisco just outside Chinatown. Itried to pick up ota hd channel with the onair gt with no luck. I live in an apt building 5 floors high with no major tall buildings around plus I'm only 4 miles away from towers.

I don't think there is a roof top antenna at mu building and hence no OTA channels. I also bought indoor radio shack antenna, I can hear audio only but very fuzzy picture.

So the questions is do I need a rooftop antenna AND indoor antenna with Onair GT to be able to pick OTA channels?

Thank you....

the permanent antenna .

i hooked up a dipole antenna; so, i knew i was not going to get a great pic on all channels, but wanted to watch the games today i was surprised that FOX came in super crisp w/ that little wire antenna. so, here are my questions:

1) while the game was wide screen, the commercials came in 'small screen'
mode showing black on the sides of the pic. is this normal for OTA?

2) for those w/ an aquos (mine is a 64U), the FOX channel viewing mode was
in full screen mode - referring to the picture filling the screen. when i
switched to nbc, which was not as sharp by far, the viewing mode was
dot by dot. what might cause that variance in the viewing modes on
different networks? pq? signal strength?

3) i was reading up where larry said that he thought the difference between
sat and OTA hd picture quality was deminimus. if that's the case, why
would one sub to HD and run OTA? i was thinking of doing one or the
other - leaning to OTA, as i really only watch the networks and the kid
watches cartoons which are not in hd anyway....

thanks in advance

shark

got the answers for #1 and 2 which make sense to me. i'll have to do a bit more reading ...thx.

shark

We need a bit more information before we can give you an answer, Btran.
1 -- What's an "On air GT?"
2 -- What floor of the five story building do you live on?
3 -- Are you on the side of the building facing south or west where you can see Sutro Tower and Mt. San Bruno?

With digital TV there's no such thing as a fuzzy picture or audio only. You either get a perfect picture or no picture. It's not like analog where the signal fades into "snow". The digital signal has to be strong enough to be detected by the receiver, then you get a perfect picture. If you were getting a fuzzy picture, you were watching the old analog NTSC channels.

You probably need to scan for the digital signals. Most receivers require that you scan to detect the digital stations. Did you do that?

Give us a report and we'll help you some more.

Larry
SF

You already found one of the delights of digital TV. If you get enough signal to get a picture, the picture is perfect. As I wrote to Btran above, you either get a perfect picture or no picture. Apparently your dipole is getting enough signal for FOX to work fine. How's it working for the other stations?


[/quote]
It's not your set, it's the way the stations transmit the picture, and it has nothing to do with signal strength. Digital stations can transmit HD wide screen, SD (standard definition) wide screen, or SD 4x3 - the old size picture. The programs and commercials can be HD, SD wide screen - seen a lot on PBS, and or 4x3, and you'll usually find a mix. Lately, I've been seeing some 4x3 programs with HD commercials.

The SD programming will not look as sharp as the HD. HD is either 720 or 1080 lines, while the SD is only 480. You'll see lots of variations in picture quality. HD is like looking out a clean window. SD can be real fuzzy sometimes. Some stations only transmit SD. To date, the stations transmitting HD in the Bay Area are 2-KTVU-FOX, 4-KRON, 5-KPIX-CBS, 7-KGO-ABC, 9-KQED-PBS, 11-KNTV-NBC, 20-KBWB, 36-KICU (only football so far), 44-KBCW-CW and 54-KTEH-PBS.


There are several HD channels on cable or satellite in addition to the networks. If you only watch the network programming, then OTA only will work fine for you. If you want ESPN, TNT, HDNet, Discovery, History, Food, Home and Garden, Universal, etc in HD, you'll of course have to sign up for Dish or DirecTV satellite or Comcast cable HD.

What I was saying on the difference between the quality of sat vs OTA, is the OTA is slightly better when you compare the signal received from your antenna to the signal received via satellite. You get the sharpest picture with an OTA antenna, but you get more reliable service, I think, with sat or cable. Multipath reflections, planes flying by, even buses going by can cause reflections that can break up the OTA signal.

Hope that helps. Enjoy your new HDTV... and if you don't get all of the OTA stations, you'll need to install a better antenna with more gain. Sounds like you're off to a good start with your dipole though.

Larry
SF

larry,

thanks for the reply. did i read you correctly when you said that i will basically get either "no" video or great video on the digital channels? kntv was not clear at all, but i just assumed that to be due to the vhf nature of that one station. the other channels i could see, that were noted as digital by my tv, were not close to being as sharp as fox was; i assumed that to be due to my using the lousy dipole...lol. the channels that were not as crispy as fox were kpix and kron. note that i did see the analog versions of these channels - i believe the digital versions were noted w/ a .1 ..ie 4 = analog and 4.1 = digital.

i'm behind tower market, so close to sutro and am i correct in assuming that if i use a 'real' antenna (ie a channel master 4228), i'll most likely get all of the networks as crisp as my fox channel was today?

great reading here.....tia.

shark

Larry,

Onair GT is usb hd/qam capable tuner. I'm on 2nd floor of 5 stories, looks like I'm facing West toward North Beach. Yes I did scan for ALL stations but the only ones that showed up was analog cable. I don't have outside roof top antenna, can this be the cause? I find it hard to believe that being 4 miles away from towers and signal is not strong enough to pick up. What should I do now? Thank you.

bt--

You're probably awash in multiple strong signals from all the Sutro stations...that's the problem, it's called "multipath" and it's death for 8VSB DTV reception. Look at your OTA analog UHF stations for a clue. My guess is that they appear full of "ghosts", which is the NTSC manifestation of multipath. With DTV, instead of ghosts, you get no picture or sound. If you see lots of NTSC ghosts then you need to use a more directional antenna to select one of the strong signals out of the soup for DTV reception.

A 4228 near the base of Sutro Tower? Oh my, that would be an interesting experiment. The 4228 is a long range antenna, so I wouldn't normally recommend it within 30 miles, unless the signal is obstructed, which doesn't appear to be the case here.

In the DTV world, there are three levels of service:

1) No signal
2) Good enough signal ("perfect" or at least as good as the source)
3) Marginal signal - with dropouts, audio and/or video. This can be from a signal that is not quite strong enough or from noise and other distortions.

VHF stations have to contend with more noise as re DTV, but what you describe sounds like the analog signal. For KNTV, are you getting both 11 (analog) and 11.1 (digital)?

Was there no CBS 5.1 OTA broadcast during Monday prime-time or did my set get crazy?

Is there a website with scheduled outages, e.g. for broadcast antenna maintenance?

falcon,

yes, i did pick up 11 and 11.1 per my guide after the scan, but they were not nearly as clear as FOX was. in fact, it was plain bad. i got all excited as FOX was the first channel i had tuned to because of the game and then PQ went downhill from there..lol.

i'm definitely within the 30 miles you stated in your reply. if not the 4228, what might you suggest? on that note, would there be another antenna that would allow me to receive KNTV, 11.1, along w/ the UHF channels? thx...

shark

I note that both Larry and I are well within 30 miles of Mt. Sutro and are using 4228s to good effect. The issue, as we have both (often!) stressed before, is not signal strength but "gain" (i.e., directionality). The 4228 has very high gain, which helps it discriminate against signals from slightly different directions. An 8VSB tuner needs to have one of the received signals a certain number of dB stronger than the others on the same frequency or it cannot reliably handle it. If the actual signal strength of that beam from the antenna overloads the input stage of the tuner, then the solution is to insert attenuation in the signal path.

Last night around 11 p.m. I switched to channel 9.1 from channel 9, which was showing the same program. On 9.1, I could hear ominous background music (the show was about the Kennedy assassination), but not the voices speaking.

I switched back to channel 9, and there I could hear both the music and the voices. The other digital channels seemed normal.

Reception gremlins? Problem with channel 9.1? Or a problem with my very new set? (I use OTA only.)

I did the exact same thing, not a problem with your gear. 9.1 is HD feed and the audio stream had issues. This has happened on other OTA sources as well.

I have been getting both OTA and SAT HD for 2 yrs now and this same type of audio problem has happened to me only a hand full of times.
Bw