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Discussion Starter · #1 ·
Because of terrain, my prospects for successful DTV reception didn't seem good. A few weeks back, I searched archives in this forum for threads about local installations.


Inspired by a few threads in the archives, I recently installed an OTA antenna for my Dish 6000 to receive the local Los Angeles DTV broadcasts. I don't have clear line of sight to Mount Wilson, which is 46 miles distant. (For local readers familiar with the area, I'm in hilly terrain above the intersection of Trabuco Road and Lake Forest Drive in Lake Forest.) There's a ridge 0.3 miles away that's 44 feet higher than the elevation at my house, as measured with a GPS. Plus, the ridge has trees and 2-story apartments, offset somewhat since my roof-mounted antenna is 25 feet off the ground. Beyond the ridge, there's nothing else in the way.


I installed a Radio Shack 15-2160 yagi with one of their 30dB mast-mounted pre-amps. I used a Winegard DS-3000 J-pipe mount that's securely bolted to the fascia on the eave of my roof line. This mount is nearly identical to the mounts that come standard with Dish Network SATV dishes, except the pipe is longer and can be cut to length. I found this mount online at dishplace.com. Starkelectronics.com sells them for less, but was out of stock.


I've had mixed results with DTV reception... KABC, KNBC, KTLA(WB) are consistently in the high 70s to high 80s. KCET(PBS) is usually in the low to mid 60s and exhibits occasional dropouts. KCOP(UPN) is often 55 to 65 and also exhibits some dropouts. Most of the time, I can't receive KCBS or KTTV(FOX) at all. I've never received a KCAL9 (local independent) DTV broadcast, but I haven't performed automatic DTV searches since the antenna installation, either. Numerous Hispanic stations have strong DTV signal levels, but these don't interest me. There is some variation in signal consitions, as would be expected.


I'm not confident that my antenna orientation is optumum, either. For work, I occasionally rent a spectrum analyzer. Sure wish I had one now to help with antenna orientation! Or, that Telemann HiPix HTPC card that can show concurrent receive signal levels for all DTV stations!!


Regarding picture quality...

I noticed that even SD OTA broadcasts are significantly better than the corresponding local station broadcasts from Dish Network. I suspect that Dish is compressing signal bandwidth more than the local OTA transmitters.


I believe KABC is broadcasting 720i format while the others are boradcasting 1080i. Right? Does this explain why KABC SD fills the screen while the other stations' SD has bands at the sides?


Lessons learned...

I'll mention a few antenna complications I encountered. A warning might help others...


1. Until halfway through the installation process, I realized that some stations don't broadcast DTV 24/7 - KCET(PBS) for one, maybe there are other stations. It's hard to find stations that aren't broadcasting!! (duh)


2. I used the u-bolt clamp that comes with the Shadio Rack Yagi, and it was a tight fit over the Winegard mast. This presented some problems. I used a compass to initially aim the antenna boom, then noticed that the azimuth would change when tightening the two u-bolt nuts! Tighten the rear-facing nut, and the antenna boom would turn to the left. Tighten the front nut, and the boom would move right! This was not a minor effect. I had to keep checking azimuth with the compass, and carefully alternate tightening. Even then it was not an exact, known azimuth adjustment.


3. Before mounting the antenna, I used a bubble level to make sure the mast pipe was plumb. I was surprised that this did not assure consistent antenna elevation because of the antenna's u-bolt clamp! After numerous trials with strange results, I discovered that antenna elevation was changing significantly with each azimuth adjustment. Finally, I ended up setting elevation after each azimuth adjustment by (a) loosening the J-pipe at the mounting plate, (b) reading a bubble level laid on the antenna boom while tilting the mast as necessary to get the desired elevation, and (c) tightening the J-pipe mount with an eye on the bubble level to make sure it stays at the desired tilt. Once the J-pipe mount was tight, the elevation was rock solid.


4. Due to problems 2 and 3 above, I wasted two hours making small antenna adjustments with large introduced errors. Only the last few trials had reliable azimuth and elevation settings. Since rain was threatening when I performed my antenna adjustments, I need another round of tests to optimize antenna orientation. Then, I'll consider next steps.


The RS Yagi is quite sensitive to orientation. From my house, the azimuth spread is only a quarter degree to cover all operating DTV stations on Mt Wilson. The KCBS tower is offset from the others (as seen from my house) accounting for roughly half of this spread. This might explain why I rarely "see" KCBS.


The Radio Shack yagi specs do not provide a gain/azimuth plot, but I'd expect this antenna to have a narrow frontal lobe. I am surprised how sensitive some DTV stations are to antenna orientation, while others seem insensitive.


I used the lat-lon coordinates at http://100kwatts.tmi.net/tv/LAX.html and an online geodetic distance calculator (dead link today) to compute the azimuth to each local DTV antenna. This showed me the spatial relationship between the stations as they range from WNW to NNW, as viewed from my house, which explains how antenna azimuth adjustment might change reception for the various stations.


I have wondered if all these stations are operating at their full licensed output power.


Comment on Radio Shack equipment: In the past I designed products that were sold by RS. Their specifications and acceptance criteria are significantly higher than most people would assume. Their products are probably suitable for many applications, and there's no reason to spend more unless it's necessary. That yagi retails for $21.99, an inexpensive experiment.


I realize my installation my be pushing the envelope due to marginal OTA conditions. If ongoing experiments with antenna orientation don't improve my OTA reception, I might consider a better antenna and/or ChannelMaster UHF-only pre-amp.


All comments welcome...

Gary
 

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Gary,


Hi. Welcome to the world of OTA DTV reception in south Orange County. The one thing you can count on in this area is that everybody's situation is different. I am in a

small valley with nearby hills all around in Mission Viejo,

about 55 miles from Mount Wilson. I am able to get all the LA stations with varying signal strengths using a combination of 2 small indoor yagi antennas (Silver Sensor).

One is actually mounted outside and uses a pre-amp. The other is indoors pointed out an upstairs window. I am able

to get KCBS most reliably with the indoor antenna at 93-100

signal strength on the Hughes E86 receiver. I get channels 5,11,13 from indoors as well. The other stations I get from

the outdoor combo. A group of other HDTV enthusiasts from the area have been getting together to share experiences and

work on each individuals reception issues. Send me a PM if you want some more information.


Bruce
 

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Hi there guys.. I am in the North Orange County area and I am just getting ready to get HD into my house. I did a quick test with a small tv with rabbit ears and I can get KCET. I need to get an antenna as was wondering what the best one is to get. First place I am going to mount is just above the TV. I need to mount it into an attic environment. Any suggestion on what is a good antenna. I dont want one of those large ones..
 

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Unfortunately, Radio Shack antennas don't work on the higher UHF channels like 60 (KCBS), 59 (KCET), and so on. I've seen this limitation for decades with many UHF-only antennas. Have you tried a real antenna from Winegard or Channel Master?


It's not that Radio Shack products are bad because they are Radio Shack--just that their UHF yagis are designed with decent gain only on the lower 30 or so channels. This is a problem inherent in so-called "yagi" design. A true log-periodic or bowtie antenna is a better antenna for our regions. Most people report slightly better reception on some Radio Shack yagis actually off the sides somewhat, showing that they don't have a front main lobe.


The front lobe on any of the good antennas is wide enough that you should only have to aim roughly.


Does KCAL-DT still sign-on only evenings?


Filling the screen has nothing to do with the vertical resolution, 720p or 1080i. Filling the screen is done only with 4:3 aspect ratio, regardless of vertical resolution. A station can (gag) choose to violently chop off the top and bottom of the picture to force a 4:3 picture into 16:9 or 14:9 aspect ratio to please those fearing screen burn-in, but everyone else suffers from lack of picture or anamorpism.
 

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I'm in south orange county, and my bedroom window faces south, so I'm pullling San Diego OTA DTV with a modded radio shack double bowtie.


I get CBS, ABC, and PBS fairly well. Dropout for a few minutes at a time a few times each day. NBC is struggling to come in as I get a horribly broken up picture most of the time. I think a preamp may help.


How common is a preamp with an indoor antenna? I don't have a lot of flexability at all with antenna positioning. Right now the antenna is on a tissue box, on the top of my TV with several articles of mail on half the box so that the antenna is angled upwards slightly. Hehe, its funny but it has to be like that to pull in these stations as consistantly as possible. I fear adding a preamp would force me to find another location for the antenna which isn't nearly as good.
 

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Well impatience got the best of me, and I went out and bought a radio shack preamp for $60. And so far (/me knocks on wood repeatedly) it has locked in NBC which was almost never solid, but rather pixel hell.


I just hope it isn't an atmospheric coincidence. A little consistancy would be nice, but I guess that is truely getting ones hopes up in the OTA world =D
 

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Discussion Starter · #7 ·
Well it's good to see there are others struggling with the same problems. While the terrrain provides challengesfor some, it could be a lot worse.


WJD and azazel...

Picking an antenna depends entirely on your location. Thre's no hard and fast answer to "the right antenna". From what I've learned in the archives here, it's largely trial and error. For S. Orange County viewers seeking DTV reception from L.A. stations, we don't have an especially strong signal due to distance, and local conditions can make matters worse. I'd suggest two things:


(1) The azimuth toward Mt Wilson for South OC is about 330 degrees or so, referenced to True North. This is NNW, check whether hills are evident in that direction. If you have hills or ridges higher than your antenna, your situation is not ideal.


(2) Use the Search Utility to look in the archives of this forum using arguments like "Orange County", "Irvine", "Mission Viejo", "Coto de Caza". "San Clemente:", "Laguna" etc and you can read about the experiments of other local DTV experimenters. There are quite a few.


Regarding attic mounts - Expect a lot of signal loss. I considered this until I realized I'd be aiming through stucco which has a metal lattice inside. Outdoors is best, as high as you can get it, but you gotta do what your situation permits. Certainly there are locations where indoor antennas will be fine. Also it might work fine until weather conditions degrade the signal further.


There are many viewers that get good signals from San Diego DTV stations. I recall reading about posters in Burbank that get great reception from SD, 105 miles distant, and lousy reception from Mt Wilson, because they so close that they don't have line of sight!


BlueWire...

Thanks for the specific information regarding limitations of the Yagi antenna design. I will try different off-axis orientations as a first experiment, then will probably move on to a "real antenna".


I see many people praising the Televes DAT75(?), another large YAGI antenna. Not sure I know what a log-peridic or bowtie looks like, but investigate!


I am encouraged that my DTV reception is not bad, (and even quite good) for many stations most of the time! Now that the initial flush of enthusiasm for moderate initial DTV success has passed, I find myself being less tolerant of dropouts. I want good reception all the time.


Gary
 

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I'm in Newport Beach right next to Newport Pier and am having trouble getting reception. I can't get NBC and have poor luck with ABC. CBS is fine.


I'm using a Radio Shack VU-190XR (huge 10' antenna). I am thinking of trying one of their UHF only antennas? Would that help?


Any suggestions would be greatly appreciated.
 

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Discussion Starter · #9 ·
Nate,

For me NBC and ABC always work well, while CBS is usually missing. The CBS transmitter is west of the other stations' DTV transmitters, from the lat-lon coordinates given in the "100kwatts" link in my first message. The other DTV antennas are in a tight cluster with CBS a bit west of the others. You might try turning your antenna slightly toward the north to see if the other stations improve.


From your location, I'll bet you have good line-of-sight to Mt. Wilson providing there are no tall buildings near your house. Unless you're below the beach bluffs...


A pre-amp might be a good way to boost your signal strength. RS sells one for about $60 but some posters here have reported better results using a ChannelMaster UHF-only pre-amp.


I'm no expert on antennas. There have been numerous detailed antenna comparisons posted here, but the only thing that matters is how well an antenna works for your situation. It's trial and error.


The RS UHF antenna mentioned in the first message is only $22. If you bought one and were careful unpacking it and playing with it, you could probably return it if it didn't work. You wouldn't have to press in the plastic end caps (not removeable once inserted) to see how well it works. Same with the RS pre-amp. Once you start special ordering antennas, etc, returning them becomes a problem.


From my understanding, the single band UHF antennas perform better than combination VHF-UHF-FM antennas and are generally (but not always) smaller.


Gary
 

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I've read in here of others having very good luck with a Zenith brand UHF Antenna designed for HD use supposedly. It's at Circuit City and is supposed to be rather cheap. (price wise!) And easy to return too if it does not work for you....


Live in MV myself...waiting on Cox...though not impressed with what I hear about the first generation boxes....
 

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Jetninja,


I think you are referring to the Silver Sensor, manufactured by Antiference in England, but apparently being marketed now by Zenith. I can attest to its virtues as a UHF only DTV antenna. It is small, about 1 ft. long and is highly directional. I've used it to recieve the San Diego stations without a pre-amp, a distance of over 70 miles. I can get the LA CBS station at my home in MV, about 55 miles. As I wrote earlier in the thread, I use 2 now, one indoors and one outdoors with a pre-amp to get all the LA stations. It's nice in that its small enough that my HOA did not have a problem with me mounting it outdoors.


Picture Here:

http://www.antiference.co.uk/indoor.htm


Available at:

http://www.digitalconnection.com


for about $50.


I also tried a ChannelMaster 4248 8-bay bowtie, but it didn't work well in my location. But there are others in

this area that it works well for. Like others have said,

trial and error.


Bruce
 

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Bruce --


Good to hear you finally got something to work! Since our last "local" meeting (we're overdue for the next one - let's try right after New Year's...) I've spent some time doing a bunch of tests on various indoor and outdoor antenna/preamp combinations. As soon as I get some time I'm going to post the results here, but I can share a couple of interesting things that came up during this effort. First, I finally found a RS preamp that works as well as the CM 7775. The model number is 15-1171. I also found that the now-discontinued RS 15-1862 amplified indoor antenna works better than either the Silver Sensor (with 7775...) or the DBT (also with a 7775...).


I did some experimenting with "stacking", both horizontal and vertical, with first two, and then four Silver Sensors. First I tried a horizontal stack arrangement (using some PVC parts; I have pics I'll also post...), with a spacing of about 40 inches. Without a preamp I was able to get only 3 (of the 10 LA stations broadcasting at the time...) with a continuous lock. With the 1171 preamp the single SS was able to add one more, for a total of 4. With the horizontal "stack", without the amp: 4 locks; with the amp: 7 locks.


I then tried to vertically stack two of the SS's with surprising results. At first, I couldn't see much of a difference until I found that if they are offset so that the "upper" SS is placed about 6 inches in front of the "lower" unit, which is separated vertically about 12 inches from the top antenna, it makes quite an improvement. In this configuration, without the amp: 7 locks; with the amp: 9 locks (!). Next, I tried a "quad" stack configuration with 4 SS and got 9 solid locks with no amp. With the amp: 10 out of 10 locks, with most "pegging" out the E86's signal readout (6-100s and 2-93s...).


I also did a horizontal stack (also 40 inches...) of two RS 2160 yagis, with and without an amp, and I got the highest numbers I've seen from my location for any antenna without an amp: 10 locks 6-100s, 1-93; and with the amp: 10 locks, 8-100s, 1-86, 1-79. I also tested my 4228 and a 4221, mainly as a "control" and I got numbers similar to what I have in the past (4228/7775: 10 locks, 5-100s; 4221/7775: 10 locks, 4-100s...).


I found another interesting thing, by accident. One of the RS models I tested was their "current" 15-1890 model (the one that "tauts" HD compatibility and looks like two paper towel holders on a curved arm...). This antenna normally is a pretty poor performer (1 lock...) but I inadvertantly knocked it over, so that it was "resting" on the front "tube" and all of a sudden the numbers went up (5 locks, 2-100s...). Wierd, huh?


Finally, I found the amplified 1862 to be the best performing indoor antenna of all that I looked at (9 locks, 5-100s...). Why is it that RS chooses to discontinue its best performers? For the DBT, I can understand because it basically looks like a cheap Hibach grate, but the 1862 looks good!



All these numbers were taken outdoors (on my upstairs deck...). When I moved indoors to our loft area, where the antennas point out a 3 foot by 9 foot skylight/window in our living room, performance went way down. I tried the 4221 (w/amp: 7 locks, 2-100s), the "quad" SSs (1-2 locks; too directional for this indoor location...) and the 1862 (7 locks, 0-100s...). Curious, I then decided to see if there was a way to "stack" a couple of 1862s. I tried several different combinations but found the best results when I set them up side-by-side (9 locks, 4-100s...). I now have these connected into a new Zenith HDV-420 OTA receiver, which has a better tuner (just like your Broadcom friend said...) and a Sony 17-inch LCD panel and it works great. I've had no dropouts in two weeks on any channel.


Anyway, I hope to be able to post the complete results and the photos sometime this week.


-- Gary
 

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Gary..


I am just getting ready to add my HD attennna and I will welcome any info that you can provide. I am in the Northen Yorba Linda area and currently I have the Silver Sensor just sitting outside. I get about 5 stations, but they signals fluctuate. Any info that you can provide will greatly be appreciated.
 

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You are closer to Mt. Wilson, which is good. Do you have any hills, big trees, buildings, etc., between you and and Mt. Wilson? If so, your biggest problem is likely to be multipath. In that case, a 4-bay "bow-tie" type, like the CM 4221 or WG 4400, might work best. You can get these online at www.warrenelectronics.com or www.starkelectronic.com. If you do go this route, I'd also recommend the CM 7775 mast-mounted preamp.


Seeing how you can get at least five channels with the SS, I'm guessing multipath is not a big issue. I guess the first thing I'd try is the Radio Shack UHF-only yagi (model 15-2160...), as it is inexpensive and readily available. If you can't get at least 10 stations locked on with no dropouts. I'd go back to Radio Shack and pickup a model 15-1171 preamp. Don't bother with any of the other RS models.


Good luck!


-- Gary
 

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Actually I am able to get 2,4,7,11,13,9, PBS(Both Channels). LIke I said I do have some drop out but not a lot. I am in an association and would like to mount the attenna on the outside to maximize my reception. I am on a hill, but I am towards the top of it. Not in the valley. THere are some trees around towards mt wilson. I have a neighbor that has an attenna and says he is getting excellent reception. I am not sure if I can rely on his evaluation since he is not to technical. So I am looking for something on the small side.. Would this change your recommendation.
 

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Both the 4221 and the RS 2160 are relatively small, comparatively speaking. The 4221 is basically flat, about 24" x 48". The 2160 is about 3' long, pretty short for "yagi"-style.


I think you will do fine with either so I'd give the RS model a shot, if only that it is available locally. Actually, you might also just want to try adding the RS 1171 amp to your existing SS. It might be enough to eliminate the dropouts.


-- Gary
 

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I have read that the channelmaster and the silver sensor provide the best results. Are you saying that I can get the same results the above antennas?
 

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First of all, the 4221 is a Channel Master antenna. It is basically "half" of the 8-bay CM4228. I've found very few cases where this antenna won't be one of the best performing.for digital reception. The Silver Sensor is one of the best indoor antennas available. It works so well that for some situations, it's all you need. In almost all cases, however, the RS 2160 "yagi" will work better.


As I said above, you might just try adding the RS 15-1171 amplifier to your SS. It might be all you need to allow your receiver to lock onto all the channels,


-- Gary
 
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