San Francisco, CA - OTA - Page 131

Originally Posted by GGSkater

I reworked my uhfblogspot antenna -
Going to the longer 9" design (vs. the 7" design), I am able to pick up KNTV and the other 2 NBC stations.

Originally Posted by GGSkater

One thought I've had is that if I can get this to work, it might be an interesting volunteer project to help out the "elderly and the poor" that the news media talks about as having been sluggish getting the coupon. Do these reporters understand the extent of the "antenna issue"...that is, the previously fuzzy / snowy analog signal is often completely dark for some locations in digital?

Originally Posted by DEEPFRINGEGUY

Here's a nice CECB (coupon-eligible converter box) chart that you might find interesting. Maybe you already have a link to it on your site, I forget... but, it's worth mentioning again:

http://en.wikipedia.org/wiki/Comparison_of_CECB_units

I also have the Insignia (same as Zenith) and it's a much better box than some of the other brands out there. It also allows manual adding of channels in a way that is compatible with OTA antenna rotors.
- DFGY

Originally Posted by Calaveras

Hi Larry,

Just a couple of notes. KSPX digital is on 48 so you probably can't get it because KSTS analog on Mt. Allison is too strong. Even though I'm mostly blocked to KSPX analog on 29 which transmits from near Placerville, it still causes interference to KPIX digital.

Maybe you're having trouble with KOVR 25 since KGO is on 24 and KTSF is on 26. Talk about a strong signal sandwich! Those will go away if we ever have the transition.

How about KXTV on 61? Any luck there?

Can you get KSBW 8? If so you might be able to get their digital channel when they switch to 8.

Has anyone noticed that KTNC digital 63 is off the air for like a week now? I wonder if they've gone off the air to finish installation of their channel 14 antenna? They're already strong here on 63 so I expect them to be really strong on 14.

Chuck

Originally Posted by scottndsky

I've only recently installed a CM4228 in San Jose, and ... I'm able to pick up the following (in order of virtual channel):

KTVU (56)
KRON (57)
KPIX (29)
KGO (24)
KQED (30)
KNTV (12)
KDTV (51)
KOFY (19)
KRCB (23) hit-or-miss
KTSF (27)
KMTP (33)
KICU (52)
KCNS (39)
KBCW (45)
KSTS (49)
KTEH (50)
KCSM (43)
KKPX (41)
KFSF (34)
KTLN (47) on occasion

Granted, several of those are non-English stations I won't be watching anyway. However, counting all of them, 20 digital stations with a 4228 is more than I had hoped for. I'm quite pleased with it.

I'm curious why your 4228 won't pick-up both KGO on 24 and KPIX on 29 without rotating it? They're both coming from Sutro, right?

Also, what are the 11 stations you're pleased about getting with your SR-15 locked down?

Regards,
Scott

Originally Posted by bettygunn

1) I currently can pick up ch. 8, 28, and 40 analog with my antenna in fremont and was wondering since 8 is based santa cruz way and 28 and 40 are called low power does that mean they wont reach fremont when they go digital because of what is called the cliff effect?

Originally Posted by DEEPFRINGEGUY

Maybe we can get Larry to buy one of the new ones [new 4228] and tell us how good it is?

Originally Posted by Calaveras

DFGY,

In order to clear the first ridge I'd have to be up at 105' and that's not going to happen. It's not the gain I need, it's the multipath rejection. The more antennas you phase the weaker the side lobes are.

I've been in the ham radio game for 40 years and there are always a few neighbors who hate antennas. I don't want to sound mean, but the only way I can deal with them is too ignore them. I have a ham friend who put up a 40' tower and the neighbor's wife was so distraught that they moved. I don't understand the "I hate antennas" mentality.

Even out here in a rural area on 10 acres with the nearest neighbor 400' away and the next two nearest 800' away, I'm still getting hints that they don't like antennas. I'm sorry people but there are no antenna ordinances in the county and no one has a right to a view.

If you saw the images I posted earlier, you can see the work platform just below the top of the tower. From there I can reach the antennas. I use a winch with wire rope to crank the mast down with the rotor removed to reach the top antennas. All of this is why I'll eventually switch to a crank-up tilt-over tower that allows access to the antennas while standing on the ground.

Chuck

Originally Posted by scottndsky

I live in south San Jose near the intersection of Hwy 85 & 75 (Oakridge Mall).

I have a Omni-Directional FM antenna similar to this:


And I plan on getting a ChannelMaster CM4228 (the original version) to point towards Sutro Tower in S.F.

I'd like to understand how I should properly combine these together? Would a simple 3 dB splitter in reverse (combiner) do the trick?

Regards,
Scott

Originally Posted by scottndsky

Just a follow up...

I didn't end up combining the FM with the CM 4228 as I originally planned. Instead, I ran a separate cable for each antenna. The 4228 goes to a 3dB splitter between my TV and my Tivo HD. The FM antenna goes directly to my old-school stereo receiver.

Pictures attached...

Regards,
Scott

Originally Posted by DEEPFRINGEGUY

Chuck,

Have you ever tried experimenting with "tilt angle?"
http://www.atechfabrication.com/prod...cal_tilter.htm

These add weight, but I'm real curious what one of these might do for me...

- DFGY

Originally Posted by Calaveras

I tried it as an experiment once and it made no difference. I suspect in the majority of cases it won't make any difference since the signal is coming in at close to 0 degrees. If you look at the vertical pattern for the CM-4228 here:

http://www.hdtvprimer.com/ANTENNAS/cm4228.html

you'll see the antenna needs to be tilted up about 8 degrees to see 1 dB difference in the gain. It seems pretty unlikely that the signal would ever be coming from more than 8 degrees in elevation unless you live right under the tower.

I can tell you that this tilt device doesn't exist in ham radio. If it made any difference everyone would be using it.

There is one exception I knew about. About 20 (?) years ago I heard that K6QXY who lived in the north bay somewhere and had a huge array on 50 MHz had the ability to tilt his antennas down a little under the theory that would allow his main lobe to be put right at 0 degrees compensating for ground effects that raise the lobe. But this was for ionospheric propagation, not ground wave. I remain a bit skeptical that it did anything.

At UHF frequencies, even at only roof level, the antenna is so far above the ground in terms of wavelengths that I doubt the ground has any noticeable effect in raising the antenna main lobe.

Chuck

Originally Posted by DEEPFRINGEGUY

Hi Chuck,

A-tech was talking about the Yagi style that we're using and the site mentions that if you have a horizontal stack, like you do, that the vertical and horizontal beamwidth is more narrow than a single 91XG, for instance; in theory making them more sensitive to tilt-angle.

Back when I was designing my new rig, I went out to this site and checked my location.
http://weltwireless.home.att.net/tec...alculator.html I'm not sure if I selected the options correctly, but it came back and said that for my latitude and longitude, I should tilt downward 2 or 3 degrees for optimum signal. It seemed be able to factor in the curvature of the earth, etc. Is this all a bunch of hoowey?

- DFGY

Originally Posted by DEEPFRINGEGUY

Nice little setup there Scott! No amplifier?

I think you did the right thing by not combining the two. I just got through raising my FM antenna up to 19' this afternoon. At 8' KDFC was in/out of HD)) and analog. Now it's solid HD)).

Originally Posted by DEEPFRINGEGUY

If you find that you want to increase your db's a little bit more, try replacing your coax with LMR-400-75. It makes a big difference over RG-6 and a significant difference over RG-11.

Originally Posted by Calaveras

Hi DFGY,

I'm not sure exactly what that page is referring to. Looks like it might be wireless internet or something similar where the distances are usually short. In that situation with a high gain antenna on one end, like one of those 2.4 GHz dishes, tilting could be very important.

I tried plugging in numbers more typical for fringe area TV reception. I pretended I was out in the Sacramento Valley looking to receive Walnut Grove over flat terrain at long distances like 50 or 60 miles, using 2000' for the transmit antennas and 20-30' for the receive antenna. I get tilt angles less than 1 degree. Even two 91XGs are not that narrow. I find I need to move my antennas +/- 5 degrees to see any real change. Also I don't believe that horizontal stacking affects the vertical beamwidth. One needs to stack vertically for that.

Here's something that may be of interest, a distance to the horizon calculator:

http://newton.ex.ac.uk/research/qsys...ysics/horizon/

For a TV station with an antenna at 2000', the distance to the horizon is 55 miles. If your TV antenna is at 33' (10m) your distance to the horizon is 7 miles. If you add those together, that 2000' antenna appears to be sitting on the horizon at 62 miles. You can see how important it is for fringe area reception to not have any hills in the way.

I believe the best thing you can do is to get your antenna above the local ground clutter, mostly buildings and trees, and that will maximize the signal and minimize multipath problems. Much higher than that probably won't do much good unless you get high enough to peak over some distant hill or building.

The best situation of course for fringe reception is live on top of a hill. I've often said that KSBW 8 is one of the strongest analog stations here even though it is 116 miles distant. But with their antenna at 3437' and my antenna at 2640', the summed distance to the horizon is 135 miles so they're not below the horizon here! Only any intervening low ridges would cause a problem.

Chuck

Originally Posted by DEEPFRINGEGUY

Just FYI,

KGO (ch. 7) is supposed to run a DTV test this evening at 6:15pm.

Originally Posted by scottndsky

Are you sure about that? That's during their ABC 7 News at 6:00 p.m.

There's no mention of is here either:
http://abclocal.go.com/kgo/feature?s...nfo&id=6339723

Where did you learn about this? How long would it last? Would they actually turn off their analog transmitter on 7, turn off digital on 24, and fire up the digital on 7?

Regards,
Scott

Originally Posted by Xn0r

Last time they did a test like this in the Bay Area, it was during the news. They basically said something like "OK we're going to be doing the digital test now" and displayed info on the screen. On the digital channels, they put out an image saying "you're ready for the transition" and on the analog channels they put something like "you are not ready" and some URLs, IIRC.

Originally Posted by bobby94928

They are NOT doing a digital on channel 7 test tonight. It is the same test that that they have done in the past as mentioned above. It only lasts for about a minute. They do the digital on channel 7 tests infrequently and then they are at like 2 or 3 in the morning. I was involved with the first one several months ago, got out of bed and everything. I was able to receive the digital signal on channel 7 with my 4228 just fine.

Originally Posted by scottndsky

Are you sure about that? That's during their ABC 7 News at 6:00 p.m.

There's no mention of is here either:
http://abclocal.go.com/kgo/feature?s...nfo&id=6339723

Where did you learn about this? How long would it last? Would they actually turn off their analog transmitter on 7, turn off digital on 24, and fire up the digital on 7?

Regards,
Scott

Originally Posted by DEEPFRINGEGUY

Just FYI,

KGO (ch. 7) is supposed to run a DTV test this evening at 6:15pm.

Originally Posted by Calaveras

For a TV station with an antenna at 2000', the distance to the horizon is 55 miles. If your TV antenna is at 33' (10m) your distance to the horizon is 7 miles. If you add those together, that 2000' antenna appears to be sitting on the horizon at 62 miles. You can see how important it is for fringe area reception to not have any hills in the way.
Chuck

Originally Posted by Larry Kenney

Is there a way to figure how much 1000 foot hills in the line of sight decrease range?

Originally Posted by scottndsky

I seem to have lost KRONs traffic cams on 4-3 for some reason.
Is anyone else still getting these?

Thanks,
Scott

… digital 4-3 is temporarily off the air due to equipment failure, and our engineers are working on it.
Thanks for watching Kron4 TV.

Originally Posted by Xn0r

Last time they did a test like this in the Bay Area, it was during the news. They basically said something like "OK we're going to be doing the digital test now" and displayed info on the screen. On the digital channels, they put out a image saying "you're ready for the transition" and on the analog channels they put something like "you are not ready" and some URLs, IIRC.