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Discussion Starter · #1 ·
Here is some test data that may help others with similar OTA problems.


I tested a few different antennas to see which one worked best for my location. I live along the foothills in Burbank and there are two large mountain ridges that block my line of sight with Mt. Wilson by about 2000-3000 feet. Multipath is very severe here, some channels I could not get with any antenna. I made all tests within about 2 hours. I also tested the first antenna (4248) again at the end to verify that conditions have not changed.



OTA signal strength measured on Dish 6000 HDTV receiver:


Results= Network Name, Channel Number...Signal Strength

N/A= no signal detected

0-50= signal detected, cannot lock onto signal


****Channel Master 4248 (Long Range Yagi) With CM-7775 Pre-amp


MT. WILSON, LOS ANGELES, DIST= 15.5 MILES


KTLA 31...54-56, solid signal, no dropouts

KCOP 32...N/A

KNBC 36...54-55, solid signal, no dropouts

KCAL 43...N/A

KABC 53...0-50

KCET 59...0-50

KCBS 60...0-50

KTTV 65...0-50


MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES


KABC 25...86-91, very strong signal

KCBS 55...74-78, strong signal


****Winegard 9095 (Long Range Yagi) With CM-7775 Pre-amp


MT. WILSON, LOS ANGELES, DIST= 15.5 MILES


KTLA 31...48-51, steady signal, marginal strength

KCOP 32...N/A

KNBC 36...46-60, no lock, rapid fluctuations

KCAL 43...N/A

KABC 53...N/A

KCET 59...N/A

KCBS 60...0-50

KTTV 65...0-50


MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES


KABC 25...68-71, very steady signal, no dropouts

KCBS 55...48-54, locks in, but drops out 3-4 times a minute


****Winegard 8800 (8-Bay Bowtie) With CM-7775 Pre-amp


MT. WILSON, LOS ANGELES, DIST= 15.5 MILES


KTLA 31...0-50

KCOP 32...N/A

KNBC 36...0-50

KCAL 43...N/A

KABC 53...0-50

KCET 59...0-50

KCBS 60...0-50

KTTV 65...0-50


MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES


KABC 25...64-72, good signal

KCBS 55...68-70, fair signal in good weather, drops out in bad weather


****Channel Master 4251 (Long Range Parabolic) With CM-7775 Pre-amp


MT. WILSON, LOS ANGELES, DIST= 15.5 MILES


KTLA 31...0-50

KCOP 32...N/A

KNBC 36...0-50

KCAL 43...N/A

KABC 53...0-50

KCET 59...N/A

KCBS 60...0-50

KTTV 65...0-50


MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES


KABC 25...75-78, steady signal

KCBS 55...53-55, drops out 3 times a minute


****Channel Master 3017 (Medium Range Yagi) With CM-7775 Pre-amp


MT. WILSON, LOS ANGELES, DIST= 15.5 MILES


KTLA 31...N/A

KCOP 32...N/A

KNBC 36...0-50

KCAL 43...N/A

KABC 53...N/A

KCET 59...N/A

KCBS 60...0-50

KTTV 65...0-50


MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES


KABC 25...56-64, good signal, can drop out in bad weather

KCBS 55...40-50, can lock in good weather only


Conclusion:

4248 best for multipath rejection, good long distance signal strength.

4251 best long distance capability, but not good for multipath.

9095 Winegard quality, but not as good as 4248 in severe multipath.

8800 high quality construction, but average performance.

3017 Good medium sized UHF/VHF antenna when used with a clear line of sight.


Note: I have not tried a CM-3021 or CM-4228. They may or may not have better multipath rejection?
 

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Glenn,


Thanks for the great info, which is similar to my own experience in a high multipath location caused by hills (San Francisco Bay Area).


However, you definitely should try the 4228 - in my experience it's even better than the 4248 at dealing with multipath. The screen (not present on the Winegard 8 bay bowtie) increases its front to back ratio and reduces the beamwidth, all good for multipath.


Les
 

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Thanks for all the info. It seems the 4248 YAGI beats the 4251 parabolic hands down.


How did you end up with all those different antennas?
 

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Glenn_L,


Here in the Boston area, I have gotton the same results as you did, at least with some of the same antennas:


I have tried the Channel Master 4248, and 4251, along with the

Winegard 9095, and they rank in the same order for me. In fact, only the 4248 of these three can get all my local channels consistently at 12 miles away.


I even screened the back of my 4251, but that didn't fully cure the multipath. (my multipath comes at an angle from the side, not the back!)

 

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Quote:
Originally posted by Glenn_L:
Here is some test data that may help others with similar OTA problems.
Glenn, Very good antenna info, thanks for the work!!

Quote:
[****Channel Master 4248 (Long Range Yagi) With CM-7775 Pre-amp

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KABC 25...86-91, very strong signal

KCBS 55...74-78, strong signal
I find this amazing!


------------------

Wendell

Technical Services Supervisor

MAETV
 

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Discussion Starter · #7 ·
Les,


I do want to get a hold of a 4228 (8-bay bowtie) and a 3021 (4-bay bowtie) for comparision. The Winegard PR-8800 is supposed to be equal to the 4228, but I'm not convinced. The shop could not get a 4228 at the time, so I settled with the 8800. I'm also thinking of replacing the reflector booms on the 8800 with a large screen to see what happens. And also play around with the distance the screen is from the pick-up elements.



dagman,


I bought the 3017 and the 8800, and borrowed the 9095, 4251, 4248 from Mike55 of this forum. He lives about a mile away from me, a little farther down from the base of the mountain. He found that the 9095 worked best for him, but he can also tune in channels that I can not even get a signal. So every location is a little different.


Glenn
 

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This correlates pretty well with the specs for the antennas. The 4251 has worse Front/Back ratio than either the 4228 or 4248, although is has higher gain and a narrower beamwidth. That's why some folks cover the back of it with additional screening material.


The 9095 has higher gain than the 4248, but poorer (wider) beamwidth. The bowtie shape of the front director elements of the 4248 yagi must really help here.


The 4228 has higher F/B and narrower beamwidth than the 4248, so there may be so improvement with that. It would be interesting to see what your results are with it, if you're still inclined to experiment some more.


------------------

You have a right to install OTA and dish antennas on property under your control.


See http://www.fcc.gov/csb/facts/otard.html
 

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I looked at a Winegard 4400 (4-bay bow-tie 1/2 size "kid brother" to the 8800) on display at the San Bernardino "Mac's Electronics" shop. It appeared to my unpracticed eyes that instead of a screen, Winegard opted for parasitic rear reflector elements mounted on the mast and spaced within the lowest wavelength of the UHF band instead. If I'm right, these elements should serve the same purpose as CM's wire screen on their 3021, and would "appear" to the incoming UHF signal as a solid reflector. In any event, Glenn, you've been of invaluable help to me and I'm sure many others in your methodical approach. I'm in somewhat less dire straits than you, but I still have a couple of problem channels - KCOP and KTLA - using the large RatShack corner-reflector Yagi. I've been reluctant to go on a buying spree to try some of the antennas you reported on, and I suspect your results reinforce my wariness. Thanks, again. (Email me if you'd be interested in trying my RatShack 15-2162 at your location for comparison.)
 

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Glen:


Thanks for your invaluable advice. I live north of you in Sunland and will be trying out your antenna suggestions in the next month or two. I have been told (by the local RS salesman and my satellite installer) that no OTA signals are possible at my location. We will see......
 

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Just curious ... Did you try the antennas without the preamps? I wonder if for Mt. wilson, since you are so close, the antennas would perform better by themselves ( since multipath and not signal strength is the problem). I also would be interested in your results with the channel master 8 bay bowtie.


Scott
 

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Discussion Starter · #12 ·
Scott,


Yes, I did try them without the pre-amp. I was hoping to see a difference in the performance of the 4251 without the amp when used on the nearby stations. But, Mt. Wilson results were all the same, no loss or gain in signal strength or ability to lock signal. Without the amp, none of the antennas could maintain a signal from San Diego. So, since I have tune to San Diego for ABC and CBS, I just run the amp all the time.


Glenn
 

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Here is some data I took, comparing four Channel Master antennas last June. This was cut and pasted from an Excel spreadsheet - hope it isn't too hard to read.


The receiving site was a hill 600' tall with a direct 22 mile LOS path to the Philadelphia DTV transmitters. Measurements taken with a Sadelco Mini-Max 800 signal strength meter.


The 3021 4-bay and 3028 8-bay both have better multipath performance than the 3022 and 3023 CM yagis (also known as 4308 and 4248). The 3021 has good gain above CH 50 - note it is equal to the performance of the larger 4248.


I will be running more detailed DTV reception tests in May with Channel Master, Terk, Radio Shack, and Winegard antennas.


KC



CH26 CH42 CH55 CH64 CH67


CM 3021 4-bay screen

Signal Strength, Front +32.3 +25.6 +2.0 +29.6 +17.2

Signal Streng, Rear +11.0 +3.0 n/a +7.3 <-20

Deepest Sidelobe -0.6 +0.7 n/a -4.0 -9.0

Front/Rear Difference 21.3 dB 22.6 dB n/a 22.3 dB >17.2 db Front to Sidelobe 32.9 dB 24.9 dB n/a 33.6 dB > 34 dB


CM 3022 small yagi

Signal Strength, Front +30.1 +26.0 +1.0 +24.7 +12.0

Signal Streng, Rear -6.0 0.0 n/a +4.2 <-13

Deepest Sidelobe -3.5 +7.0 n/a +7.0 -1.4

Front/Rear Difference 36.1 dB 26 dB n/a 20.5 dB >25 dB

Front to Sidelobe 33.6 dB 19 dB n/a 17.7 dB 13.4 dB


CM 3023 large yagi

Signal Strength, Front +33.5 +30.2 +5.0 +29.5 +16.2

Signal Streng, Rear +11.5 +12.4 n/a +12.9 +2.8

Deepest Sidelobe +3.2 +3.9 n/a +5.5 -5.0

Front/Rear Difference 22 dB 17.8 dB n/a 16.6 dB 13.4 dB

Front to Sidelobe 30.3 dB 26.3 dB n/a 24 dB 21.2 dB


CM 3028 8-bay screen

Signal Strength, Front +34.3 +27.3 +2.5 +25.9 +15.9

Signal Streng, Rear +8.5 +2.0 n/a +4.0 13.0

Deepest Sidelobe -0.6 +9.6 n/a -4.5 <-13

Front/Rear Difference 25.8 dB 25.3 dB n/a 21.9 dB 28.9 dB

Front to Sidelobe 34.9 dB 17.7 dB n/a 30.4 dB >28.9 dB

 

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Well, I apologize for the poor formatting in the previous post. It didn't look like that in the "post a reply" window when I sent it.


Hopefully, you can copy the text and use a tab function to space the numbers. If there's a way to post the Excel sheet here, I will be glad to do it.


KC
 

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This is a great thread...Recently, since I had been having inconsistent results in setting up antennas for UHF HD reception in my Home Theater installation biz, I gathered up 5 antennas that were available at my wholesaler. They were the following...


1. Channel Master 4228

2. Channel Master 4221

3. Winegard CA-7082

4. Winegard PR-8800

5. Channel Master 4248


I measured the results with my Sadelco meter from two seperate job locations in Arcadia, Ca. One location had clear view of the transmission towers on Mt. Wilson, the other obscured by a smaller mountain range and did not have clear line of sight. I did not think to measure front to back and side lobe, just the raw peaked signal numbers. The antennas are listed in the order of their performance, and performed in the same ranking at both jobs despite the fact the signal was roughly twice as high at the first job. The two top CM antennas are just fantastic antennas, and since this test a few months back have proven themselves in dozens of installations with a perfect lock on every HD station available in my area. The number 3 Winegard CA-7082 is also a great antenna and somewhat close in performance, but much larger since it is a VHF-UHF Yagi. The number 4 PR-8800 needs more explanation as I feel it has a design flaw. I had poor performance with this antenna and a comparison to the CM 4228 and 4221 (all three are bow tie designs) finally revealed why. The PR-8800 routes some of the small wires that connect the bow tie elements immediately next to each other very closely, while the Channel Master line carefully loops them further away seperately where they cross over, like they were carefully bent in a jig. I only noticied this when I read the Channel Master sheet that came with the 4228, it mentioned this as being very important. Most amazingly, when I bent and pried the PR-8800's wires away from each other in a fashion like the Channel Master's, the reading on the Sadelco when up 20db!!!! I really wondered if Winegard field tested this antenna at all, in factory dress it performs very poorly next to their own VHF-UHF model CA-7082 as well. I have seen exactly 10 PR-8800's, and they are all this way. I used up my order of them and will never use them again. Amazing. Also, the number 5 listed Channel Master 4248 was a poor performer at both jobs, despite people mentioning it repeatedly on this board.


In closing, the CM 4228 and 4221 are my top picks, they are small, reliable UHF antennas that have been around in Channel Master's lineup for over 20 years and have lots of raw passive gain. Just forget about attic mounting and put them up in the free and clear and let them do their thing.
 

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Quote:
Originally posted by Kelvin Colorspace:
Well, I apologize for the poor formatting in the previous post. It didn't look like that in the "post a reply" window when I sent it.
KC, Click on the AVSF FAQ, scroll down to the UBB section and click on the link. The page will show you how to insert the UBB code.


Plain:

1 2 3

1 2 3

1 2 3


With UBB codes
Code:
Code:
1   2    3
1   2    3
1   2    3
------------------

Wendell

Technical Services Supervisor

MAETV
 

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Discussion Starter · #17 ·
neilneil,


It just so happens I ordered a 4221 and a 4228 today. I should get them by Friday and will run another back-to-back test with all antenna's, the 4221, 4228, 4248, 4251, 8800, and 9095. Do you know the difference between the 3021 and 4221?


I was also disappointed with the 8800 performance. I did notice how those wires crossed, they had shrink wrap over one wire to keep it from touching. I may not have the 8800 to test again; I'm trying to return it in exchange for the 4228.


I have a feeling the 4221 or 4228 will work best for Mt. Wilson, and the 4248 for San Diego. If that is the case, I will mount them both and install a A-B switch at the receiver. I'll probably only need the amp on the 4248 for the 113 miles to San Diego.


Here is a link to check the topography of mountains in your area. You can pan and zoom, when you zoom all the way in the elevation numbers will show up. For me, I'm at 598 feet; the Verdugo Mountains are at 3,000 ft peak, with Mt. Wilson at 5,680 feet. Being right up against the Verdugo mountains, the signal has to make a sharp turn down the mountain. I tried to find a reflected signal, but can only pick up when it's pointed right at the tower, +/- 3-5 degrees.


Mt. Wilson:
http://mapserver2.esri.com/cgi-bin/s...x=16&MAP.y=203


Verdugo Mts:
http://mapserver2.esri.com/cgi-bin/s...=266&MAP.y=130



KC,


Thanks for posting the data; I will take a closer look at it later. I'm going to try and post in spreadsheet format too. I'll have to take a look at the AVS FAQ. Have you tried doing any modifications to the 3021? I have a metal shop and I want to do some experimenting.



Glenn
 

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Quote:
Originally posted by Glenn_L:

Do you know the difference between the 3021 and 4221?
According to the CM distributor I talked to here, the 3021 is just the retail "DIY" version of the 4221. Essentially the same thing in a different box.


neilneil,

I'm surprised with your results on the 4248. I've done a direct comparison here between it and a 4221, and the 4248 has better gain (measured by an HP spectrum analyzer) and more directionality (less ghosting on analog channels). I don't mean to be insulting or anything, but are you sure you hooked the 4248 up correctly? The terminals with the little stubs running parallel to the boom are for connecting an (optional) VHF antenna; the lead-in gets connected to the other terminals. 'just trying to get more information.



------------------

You have a right to install OTA and dish antennas on property under your control.


See http://www.fcc.gov/csb/facts/otard.html
 

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re: the CM 4248


I did try it on two seperate jobs as described. Even tried a new balun to make sure I didn't have an "open" one. I carefully examined the antenna and data sheet to check for defects and hookup, it looked ok and there is not a whole lot that could be wrong with it. There is always the possiblity I could have been out in the sun too long regarding the terminal location :), but since the 4221 and 4228 have been working out so well, and customer reaction to their look and performance so positive the 4248 is just sitting around and I really haven't considered a revisit.
 

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Glenn,


I live in the Foothills of Pasadena right under Mt. Wilson. I can not see

the antenna's up there because im to close. The only HD channel I can get is CBS-60 I picked up the Largest Yagi antenna that Radio Shack carries #VU210XR Im not sure who really makes it but im sure its a major antenna manufacture. Has anyone tried to pick up a signal in such so close? Its like im under the signal.



Regards,

Brent
 
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