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Old 23-Jan-2017, 10:38 PM   #1
dragons021
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Clearstream4 + Televes Yagi-BIII vs. Winegard 7698P

Hi, I'm looking for help in determining the better set up.

TVFool map: http://www.tvfool.com/?option=com_wr...e6a4bc42f32192

I bought a Clearstream4 and tested in an upstairs window facing W/SW (~15-20 ft.) and picked up a reasonable signal on NYC stations down the list to Fox (44 (5.1). I did not pull in NBC (28 (4.1). The weaker stations were mostly watchable, but somewhat choppy.

I then put the Clearstream in the attic, aimed at 46 degrees magnetic and picked up reasonable signals on Hartford stations down to NBC (35 (30.1), but did not pull in Fox (31 (61.1). Again, the weaker stations were mostly watchable, but somewhat choppy.

I took the reflector off the Clearstream, mounted it to a 10' post and went out on my breezeway roof, steadied it with a ladder and read a HDHomerun scan. I picked up signals on all stations, 60-70 ish signal strength, with 100 or close to 100 signal quality.

My intention was to mount the clearstream on an eave mount from the breezeway roof. Cheap install and gives me the ability to adjust. But, I discovered it is not something I am capable of doing (heights).

So I have an installer (found with good reviews on Angies list) coming Weds. Using an installer, it's more of a one and done set up, so I want to make sure I get it right.

The signals are promising, especially considering I can add 6' with an eave mount and 9'+ with a tripod roof mount to the signals I already received, but I have tons of trees in both directions and I'm concerned about when the leaves grow back. I now want the best signal possible off the bat, even if I pay more up front.

I am planning to connect to an HDHomerun Extend, using <50' coax run. I have access to the basement on both sides of the house where I'll immediately connect to the HDHomerun(s).

On one of the eaves, there is a good gap between 2 trees towards Hartford, but a huge tree in the way of NYC. On the other eave, there is a smaller gap between 2 trees towards Hartford and the best location for NYC.

I don't mind putting in multiple antennas, connecting to multiple HDHomeruns, but would obviously prefer to keep it as minimal as possible.

The gain of the CS4 is listed as 12.5db, I assume that is with reflector. Can anyone tell me the gain from the front and backside with reflector removed?

The gain of the Televes BIII on channel 7 is ~9db.

The UHF gain of the Winegard is 12-14 and 10.4 for VHF channel 7. Can the winegard pick up any channels from the back side, or is it solely in the direction it's pointed?

I'm thinking that my best bet is the Winegard on one eave, pointed to NYC and the Clearstream (w/ or w/o reflector) on the other eave pointed towards Hartford (also picking up the New Haven and Long Island stations to the East / South).

With ~50' cable runs, is there any benefit for a pre-amp? Do I need an FM Trap if I do not use a pre-amp?

I've tried to put down all my pertinent thoughts, but would be happy to clarify or answer any questions.

Thanks in advance for any help!

(note that I moved shortly after I asked for help about 4 years ago, prior to implementing the plan. This is my first attempt at OTA in the new house)

Last edited by dragons021; 23-Jan-2017 at 10:42 PM.
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Old 24-Jan-2017, 1:21 PM   #2
ADTech
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Quote:
The gain of the CS4 is listed as 12.5db, I assume that is with reflector. Can anyone tell me the gain from the front and backside with reflector removed?
A "perfect" reflector would increase forward gain by 3 dB (doubling of power) while the reception off the rear would be zero. Think of how a perfect planar mirror behind a perfectly omnidirectional light source would behave.

In a real antenna like the C4, the reflector adds around 2.5 dB to the forward gain while reducing reception off the back by 10-20 dB, depending on frequency and angle. I have a plot on my office computer that illustrates this, I'll add it to this post later this morning. I have another plot that illustrates what happens when the reflector is removed, I'll see if I can find that and also add it.

I frequently recommend that the reflectors be removed from our UHF antennas where the signals are from opposite directions. Usually works well as long as the small decrease in forward gain or undesired reflections don't rear their heads.

I haven't looked at the Televes yet, so I cannot comment about it. I will point out that, if you use separate UHF and VHF antennas, you will need either a combining device (UVSJ) or amp with that feature built-in.

Winegard has a published specification sheet that includes plots (almost impossible to read with a linear voltage, not logarithmic power scale) that illustrate the patterns including either F/B or F/R information. I don't know if you can find it on Winegard's site any more, but I do know it's on Solid Signal's site. BTW, that antenna is really big, be prepared for it's size.

I always recommend installing antennas where it's expected to be the most reliable, not necessarily where it happens to be convenient. It's pretty frustrating trying to make a convenient but lousy signal location work and customers hate to hear me tell them to move the doggone antenna if they want it to work, they just want it to work regardless of where it's put.

Best of luck!
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Old 24-Jan-2017, 1:40 PM   #3
WIRELESS ENGINEER
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It looks to me like due to all the co- channel and adjacent channel interference issues in your area that you may be best served by a 4 bay bowtie antenna pointed NE.

A preamp would cause overload so that's out.

Removing the reflector from the cs4 will likely reduce its gain to around 6dbd(8.15dbi) in two directions and you would be inviting the co- channel interference.

If it were me, I would get a DB4e antenna and aim it NE.

The DB4e has greater gain for when the leaves return yet still maintains 50 to 60 degree beamwidth so it looks to be the better choice

Last edited by WIRELESS ENGINEER; 24-Jan-2017 at 3:01 PM.
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Old 24-Jan-2017, 1:57 PM   #4
dragons021
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Quote:
Originally Posted by WIRELESS ENGINEER View Post
It looks to me like due to all the co- channel and adjacent channel interference issues in your area that you may be best served by a 4 bay bowtie antenna pointed NE.

A preamp would cause overload so that's out.

Removing the reflector from the cs4 will likely reduce its gain to less than 6db in two directions and you would be inviting the co- channel interference.

If it were me, I would get a DB4e antenna and aim it NE.

The DB4e has greater gain for when the leaves return yet still maintains 50 to 60 degree beamwidth so it looks to be the better choice
Will the DB4e pick up signal off the back? Or use it to replace the CS4 and use the Winegard for SW?
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Old 24-Jan-2017, 2:00 PM   #5
dragons021
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Originally Posted by ADTech View Post
A "perfect" reflector would increase forward gain by 3 dB (doubling of power) while the reception off the rear would be zero. Think of how a perfect planar mirror behind a perfectly omnidirectional light source would behave.

In a real antenna like the C4, the reflector adds around 2.5 dB to the forward gain while reducing reception off the back by 10-20 dB, depending on frequency and angle. I have a plot on my office computer that illustrates this, I'll add it to this post later this morning. I have another plot that illustrates what happens when the reflector is removed, I'll see if I can find that and also add it.

I frequently recommend that the reflectors be removed from our UHF antennas where the signals are from opposite directions. Usually works well as long as the small decrease in forward gain or undesired reflections don't rear their heads.

I haven't looked at the Televes yet, so I cannot comment about it. I will point out that, if you use separate UHF and VHF antennas, you will need either a combining device (UVSJ) or amp with that feature built-in.

Winegard has a published specification sheet that includes plots (almost impossible to read with a linear voltage, not logarithmic power scale) that illustrate the patterns including either F/B or F/R information. I don't know if you can find it on Winegard's site any more, but I do know it's on Solid Signal's site. BTW, that antenna is really big, be prepared for it's size.

I always recommend installing antennas where it's expected to be the most reliable, not necessarily where it happens to be convenient. It's pretty frustrating trying to make a convenient but lousy signal location work and customers hate to hear me tell them to move the doggone antenna if they want it to work, they just want it to work regardless of where it's put.

Best of luck!
Thanks, I'll have him test different locations to see if different masts make sense. The size is a bit of a concern to me, especially if I need to mount it 10' above the roof.
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Old 24-Jan-2017, 3:03 PM   #6
WIRELESS ENGINEER
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By removing the reflector of either antenna, it becomes bidirectional so all the signals from the rear as well as the front will be received.

You can try it to see if it works for you but as the polar plot shows, you may have channels on or near the same channels that reduce reception

In either case, the bowtie antenna wins
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Old 24-Jan-2017, 6:32 PM   #7
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Removing the reflector from the cs4 will likely reduce its gain to around 6dbd(8.15dbi)
No, the maximum theoretical difference is 3 dB. In actual practice, it might be a bit more or a bit less.

Note that the term dBi is only used when comparing the gain of any antenna to an idealized isotropic antenna. When comparing the difference in gain between two or more specific antennas or before and after antenna comparisons, the term dB is used since it's a simple ratio.

When comparing the "specs" from various antenna companies, it is important to note or be aware of the difference in how the specifications, either in dBi (generally as a result of computational modelling) or dBd (which is the generally used term when the values are from antenna range comparisons where a simple calibrated dipole serves as the reference), are used. Either term is correct as long as it's quantified. Conversion from dBd to dBi involve adding or subtracting 2.15 if going the opposite direction. Of course, there are a few antenna makers out there that simply state the dimensionless term dB" for antenna gain so you have know way of knowing which term should apply. If you want to see some real mathematical and marketing gymnastics, you ought to see the hard-to-find data sheet for the Winegard FV-HD30, the last of their "new" models for which they published a data sheet!

Quote:
and you would be inviting the co- channel interference.
Absolutely a concern. ATSC requires about a 35 dB difference in co-channel signal strength in order to resolve the stronger signal. If both channels are strong enough that the required differential is not achieved, then reception for both will fail. The CBS stations out of New York city and Hartford both operate on UHF channel 33 and are calculated to be of nearly identical signal power. If you go "reflector-less" and the actual signals correspond to the TVF simulation, you will get neither station's primary broadcast. Note that WCBS does operate a UHF translator halfway up Long Island, so there is a second chance for that station.

Quote:
Will the DB4e pick up signal off the back?
The technical data sheet for that model is on our website, look under the "Documents" tab on the DB4e's product page for our computed results. Reception off the back is reduced intentionally to provide addition directivity towards the front.

The following graphs were done by our design engineer as part of project to see of the horizontal spacing could be reduced so that it's overall physical size could be made smaller and thus be attractive to more retail sales partners.

The black trace is the one that is the current spacing in both plots. For the purpose of this illustration, ignore the other traces.

With Reflectors


No Reflectors
Attached Images
File Type: jpg C4_With_Refl_622MHz_rsz.jpg (86.3 KB, 414 views)
File Type: jpg C4_No_Refl_622MHz_rsz.jpg (89.7 KB, 421 views)
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Last edited by ADTech; 24-Jan-2017 at 6:35 PM.
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Old 24-Jan-2017, 6:53 PM   #8
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I dug up some data on the Televes BII that I'd actually downloaded last summer when Solid Signal started carrying it. I went back to the source for the following.

Here's the gain vs frequency plot which is posted on Televes' website:



And their datasheet:

http://www.televes.com/sites/default...030214_001.pdf

The G/F plot clearly shows that this antenna is designed for Euro-Asian BIII operation as it peaks out around 230 MHz, much like the Chinese-mad high-VHF models that MCM is carrying. That channel band conveniently includes the North American channels of 7-13 so it's a good enough although not optimized match. The peak gain shown for the USA channel 13 is around 8 dBi with the majority of the high-VHF band averaging between 7.5 and 8 dBi for the BIII. In all, very typical behavior of a Yagi with 5 directors and 1 reflector, pretty much heads-up with our ClearStream 5.

FWIW, Solid Signal, the only US seller that I've seen for Televes' antennas, shows the BIII as "Discontinued". Where might you plan on getting one, if I may ask?
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Last edited by ADTech; 24-Jan-2017 at 7:02 PM.
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Old 24-Jan-2017, 9:58 PM   #9
dragons021
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Originally Posted by ADTech View Post
FWIW, Solid Signal, the only US seller that I've seen for Televes' antennas, shows the BIII as "Discontinued". Where might you plan on getting one, if I may ask?
It only became discontinued less than a week ago (the very day I tried purchasing it from Solid Signal). I flagged it the day before when researching which VHF only antenna I wanted to try and it was available then. Amazon has (had?) it available though for the same price.
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Old 24-Jan-2017, 10:16 PM   #10
dragons021
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Originally Posted by ADTech View Post
Absolutely a concern. ATSC requires about a 35 dB difference in co-channel signal strength in order to resolve the stronger signal. If both channels are strong enough that the required differential is not achieved, then reception for both will fail. The CBS stations out of New York city and Hartford both operate on UHF channel 33 and are calculated to be of nearly identical signal power. If you go "reflector-less" and the actual signals correspond to the TVF simulation, you will get neither station's primary broadcast. Note that WCBS does operate a UHF translator halfway up Long Island, so there is a second chance for that station.
Thanks for the data on the DB4e. I tried putting the brakes on tomorrow's install to get a DB4e delivered (installer doesn't stock it), but it didn't work out. I'm going to continue with the original plan of testing the CS4/Televes vs. a suggested antenna (winegard?) from the installer tomorrow. I'll have him install the best solution (based on my testing, I'm fairly confident it will be functional without leaves on the trees) and then I'll revisit when in the spring when the leaves grow back.

Regarding co-channels, I show the following:

WFSB CBS 33 3.1 44
WCBSCBS 33 2.1 243

CBS comes in strong and clear from L.I. with the CS4 pointed at NYC or Hartford, so I'm not too worried about these cancelling out. When I ran my signal test from the breezeway roof, the app said channel 2.1 came in pretty strong - but I don't know if this was a false positive, because I wasn't in position to try to tune it on a TV.

WTIC FOX 31 61.1 46
WPXN ION 31 31.1 243

ION on 31 is a concern for blocking Fox, they're not 35db apart. This may force me into the 2 antenna solution as I'd like both Fox stations if at all possible.

WHCT 38 75
WWOR MyN 38 9.1 243

I get an easier to tune MyN station, so not too worried about 38. Not sure what programming WHCT offers or if I'll miss it.



I have a ton of co-channel interference. How much of a concern is this?

Last edited by dragons021; 24-Jan-2017 at 10:19 PM.
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Old 24-Jan-2017, 10:38 PM   #11
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I have a ton of co-channel interference. How much of a concern is this?
It's only a concern if, after installing the antenna(s), the differential is not adequate. The simulation can give you a heads-up to look closer at specific pairings to see if an issue is likely to come up. It just takes a bit of math. A lot of the warnings are not going to be an issue due to actual signal powers and the direction the signals come from vs the directivity of the receiving antenna(s).
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Old 25-Jan-2017, 3:16 AM   #12
dragons021
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Is an FM Trap only needed with a pre-amp?

I have FM antenna's galore, some within 2 miles.
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Old 25-Jan-2017, 11:17 AM   #13
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If you have strong FM signals, then an FM trap is suggested even without an amp. A lot of digital TV tuners have very limited ability to reject those signals which usually first affect the high VHF channels. You might not need the trap, but it would be prudent to order one since they're so cheap.
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