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Old 08-26-2013, 09:12 AM - Thread Starter
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http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d46ae6812d95d0a

Attic available. between 15 and 25ft above ground. 15ft towards southwest. 25 ft towards northeast. vinyl siding.

Let me know if more info is needed.
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Old 08-27-2013, 10:44 AM
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Not knowing the terrain, I'd say you have two choices. Trial-and-error from the attic, or a more certain arrangement from the roof. I'd definitely go the latter as attics are multipath nightmares and finding a "sweet spot" that allows you to get all the stations you want could be a maddening process. Or you could nail it first try.

Given the fact you have ALL those mountains around you, I'd say an attic antenna is going to be tough. You lose gain through the hills and from being in the attic.

Whatever you decide to do, keep receipts in case you have to return an antenna.

You're going to need at LEAST a mid-range UHF/VHF-Hi combo antenna. Hopefully, someone more familiar with your area will chime in.

Were it me, I'd get a longer-range combo, slap a pre-amp on the mast with a rotor and put it on the peak of the roof. Rotor's only if you want to pull in Knoxville, too. I'd prefer to have the option.

Another thing to do is drive around and see what everyone else is using in your area. Remember, the higher the elevation, the less antenna they'll likely need.

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Old 08-27-2013, 02:14 PM - Thread Starter
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thanks, doc. I think it might be a bit too much trouble for me right now. I say that due to me knowing that my wife and I will be upgrading the house and probably moving to a different area in the region once she finishes grad school. It's a nice area to be able to potentially pick up both cities, but a pain due to the hills and just being far enough away to be a hassle. I'll revisit if something in the near future changes. I appreciate your input and recommendations.
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Old 01-09-2015, 11:52 AM - Thread Starter
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alright, i'm going through with this as of two days ago. http://www.tvfool.com/?option=com_wr...2c15f06ddaaa92

I've purchased (won't receive until next week):
CM-3020
CM-7778 pre-amp
500ft of RG6
compression fittings and tool

I'm more than likely going to do an eave setup on the side of the house that already has phone, comcast, and previous Directv cables. I don't know if direct used RG6 or not but i'll have enough to replace any RG59 I have in the crawl space (very accessible for me).

Antenna will be about 20ft high.

I'll provide pictures tomorrow or Sunday of setup area.

Questions so far: What size mast should I use? 1.5, 2, or 2.5"? I see some kits only accept up to 1.5 but not sure if that would be enough for this size antenna.

There will be at least a 20ft run of RG6 (35 if I try to do a decent job of hiding cable) to the existing ground, and another 35ft+ from there to where I will plug in the preamp. I hope to be able to split from there to bedroom/dvr/htpc which would be another 25ft. Does this seem possible at this point?
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Old 01-09-2015, 12:16 PM
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Why are you getting a CM-3020? It includes large elements for low VHF which is not required in your case except for one weak station on RF 3. You should get a Winegard HD7698P or an Antenna Craft HBU55.

The most common mast size for a TV antenna is 1 1/4". Some installations like mine use a 2" mast. Nobody uses a 2.5" mast.

If you're splitting the signal 3 ways you'll need a 4 way splitter. I'd recommend a CM-3414 distribution amp.

Your success with this project will depend on how many trees you have to look through.
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Old 01-09-2015, 07:20 PM - Thread Starter
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Can you tell me why you recommend the 7698P over the CM 3020, aside from only the one low channel?

My initial split will only be two. One to living room tv and one to HTPC/dvr. Of course a future setup would benefit from an extra split, though.

The 3020 and 7778 preamp were both ordered from Home Depot so a return wouldn't be an issue. I'd just like a more detailed explanation if you wouldn't mind adding a bit. Thanks!

antenna would actually be in the 25-28ft range, so slightly higher

Cable is RG6

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Old 01-09-2015, 07:49 PM
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Quote:
Originally Posted by mrredskin View Post
Can you tell me why you recommend the 7698P over the CM 3020, aside from only the one low channel?

My initial split will only be two. One to living room tv and one to HTPC/dvr. Of course a future setup would benefit from an extra split, though.

The 3020 and 7778 preamp were both ordered from Home Depot so a return wouldn't be an issue. I'd just like a more detailed explanation if you wouldn't mind adding a bit. Thanks!

A good portion of the aluminum up in the air will be unused. The 7698 is a bit longer than the 3020, 168" vs 152" but is almost half as wide, 54" vs 95". The 7698 claims a few dB higher gain on high VHF and UHF and a few dB more F/B ratio on most frequencies. The 7698 performance is better where it counts with no wasted frequency coverage.
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Old 01-09-2015, 08:26 PM - Thread Starter
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Quote:
Originally Posted by Calaveras View Post
A good portion of the aluminum up in the air will be unused. The 7698 is a bit longer than the 3020, 168" vs 152" but is almost half as wide, 54" vs 95". The 7698 claims a few dB higher gain on high VHF and UHF and a few dB more F/B ratio on most frequencies. The 7698 performance is better where it counts with no wasted frequency coverage.
Reviews seem pretty good over all for the 7698.

Were you recommending the CM3414 instead of the Titan 7778?

Also, I may occasionally want to view a Knoxville feed (different football game or such). Rotor recommendation?
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Old 01-09-2015, 10:29 PM
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OTOH, I recommend A-D DB-8e for UHF [or a bit lower cost, a bit lower Gain CM-4228HD, even with HHH mod] since it provides significantly higher Gain and I believe will provide better protection against Multipath, typically found with 1Edge and 2Edge signals. For Hi-VHF, use Antennacraft Y5-7-13 (or Y10-7-13 if you have interest in Ch10 & Ch7):
Need antenna recommendations North Forsyth co.

Mast-Mounted Preamp Sensitivity will be a few dB better, due to reduction of the Cable Loss from the Antenna to the DistroAmp, and will have plenty of uumph to drive multiple drops. Inexpensive RCA TVPRAMP1 has separate UHF and VHF inputs:
RCA TVPRAMP1R Preamp: A Technical Review
To ensure DC Voltage is passed from the Power Insertion Module to the Preamp, either locate it BETWEEN Preamp and first RF Splitter....or ensure than you use RF Splitters with DC PASS (e.g. SATELLITE and usually NOT Cable Splitters).

I did a quick check of FM Signal Levels in vicinity of your Zipcode location (nearest Post Office?). [You should enter your location into www.FMFool.com and copy/paste the Results image into a post.] Although you don't have any Strong TV signals, there are three VERY Strong FM stations on 93.9, 103.1 and 101.7 MHz. The FM Trap in the TVPRAMP1 is fairly effective compared to other built-in Preamp Filters, but since they are designed to PASS Ch6, they aren't very effective against 93.9 MHz in the lower end of the FM Band. If you have problems receiving Hi-VHF Channels, you might want to add the Antennas-Direct FM FULL BAND FILTER on the input of the Preamp.

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Old 01-09-2015, 11:15 PM
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I think you need to run your exact FM Fool report. I didn't come up with any really strong stations using the zip code in your first post.

I was suggesting the CM-7778 plus a CM-3414 if you were doing a 4-way split. You probably don't need a distribution amp if you're doing a 2-way split only.

You probably won't like my rotor recommendation because it is expensive. There are inexpensive TV rotors but I have a very low opinion of them because so many people have trouble with them. They depend on the rotor and the control box staying in synch with each other which only happens if the rotor turns completely free. If it slows at all you'll be out of synch. The longevity of those rotors is often poor. If you can find one, the long discontinued Alliance U-100 series is a much better rotor. Even better is the Alliance HD-73.

For a current rotor, I recommend the Yaesu G450. It's a light duty ham rotor and in TV service it'll last decades.
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Old 01-09-2015, 11:52 PM
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Quote:
Originally Posted by holl_ands View Post
I believe will provide better protection against Multipath, typically found with 1Edge and 2Edge signals.
Are there any field experiments that confirm this? I've read these sorts of claims but I've never seen any data taken with real antennas to back it up. It sounds plausible at first glance but it's not really my experience.

It would be really interesting to see data taken with an ATSC analyzer that is capable of showing the reflections separate from the primary signal using different antennas. Anything short of that is probably just speculation.

I mostly have 1 and 2 edge stations and my worst multipath problems come from reflections off of mountains that are exactly opposite in heading to my local stations which are all 2 edge. The mountains are LOS to the transmitters so the reflections are almost as strong as the main path 2 edge signals.

I have many stations in other directions that are 1 and 2 edge but don't suffer from the mountain reflection problem and most have much lower multipath issues. None of them are rendered undecodable by multipath the way the "mountain reflection" group is. If they don't decode it's always because they are too weak.

I understand the ground reflection issue but I'm having a harder time buying into the idea that the vertical antenna pattern varies enough between antennas to impact the reception of the reflection much. It would have to be a very specific set of circumstances. Certainly not something commonly encountered. I would expect that in most cases the main signal and the reflection would both be in the main lobe of the antenna, especially if the reflection was any distance at all from the antenna. It doesn't seem to me that the geometry of the reflection would work with any real world antenna.
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Old 01-10-2015, 12:41 AM
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DB-8e Beats the Competition:

I did a search for a DB-8e vs HD7698P OTA Comparison Test....this is about as close as I could get:
http://www.totalhtpc.com/antennasdir...antenna-review

And here is a DB-8e vs CM4228HD OTA Comparison Test:
http://www.frugalfamilytimes.com/201...ll-review.html

Not a Comparison Test per se....but DANG!!!!
http://www.audioholics.com/hdtv-revi...-range-antenna

Good close up pictures:
http://www.audioholics.com/hdtv-revi...-range-antenna

And also ran across a 124 mph (55 m/s) Hurricane Force Wind Test on DB-8e and C1C:

PS: I am not now nor have I ever been affiliated or employed by any Antenna Mfrs.
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Old 01-10-2015, 06:26 AM - Thread Starter
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FMFool scan attached. Height of 20ft.

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Old 01-10-2015, 07:33 AM - Thread Starter
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Channel 10 (knoxville) is rather desirable but not at the expense of having to get a rotor to get most of the other VHF channels (Chattanooga). I can do without Ch 10 for now. Ch 7 is a joke and never needed.

So it seems as tho if I went with the DB8e, I could pull Knox and Chatt but only UHF. I would need the Y5-7-13 in combination, yes? Are these two able to be mounted on the same mast?
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Old 01-10-2015, 09:24 AM
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Quote:
Originally Posted by mrredskin View Post
Channel 10 (knoxville) is rather desirable but not at the expense of having to get a rotor to get most of the other VHF channels (Chattanooga). I can do without Ch 10 for now. Ch 7 is a joke and never needed.

So it seems as tho if I went with the DB8e, I could pull Knox and Chatt but only UHF. I would need the Y5-7-13 in combination, yes? Are these two able to be mounted on the same mast?

Knox and Chatt are almost in opposite directions for you. I doubt that adjusting the DB8e so that the halves point in opposite directions is going to work. This is the same as having two different antennas pointed in opposite directions and combining them through a 2-way splitter. In many cases this simply creates multipath issues. Also the Knox stations are very weak and you need a good antenna pointed in one direction for them.

If you were to go with separate antennas I would recommend the Y10-7-13. Your VHF antenna should be equivalent to your UHF antenna. For some reason people think that they need the best UHF antenna possible but can skimp on the VHF antenna. This is not true. You can mount UHF and VHF antennas on the same mast.

Here's a couple of things to consider:

The Noise Margins in TV Fool are based on a 0 dB gain antenna. With the 7698 and a mast mounted preamp you can expect roughly a 20 dB increase in Noise Margin over the TV Fool numbers. That would put your noise margins in the 40's. That's very good. The DB8e has a couple dB more gain than the UHF portion of the 7698. It won't make any difference if a particular station is +40 dB or +42 dB. I think you'll find that the 7698 or HBU55 is more convenient.

I have the extreme antennas shown in my avatar because I am a DXer, not because I need that much gain to receive my local stations. I'm trying to squeeze out every last dB so I can see some UHF stations 110 miles away that pass over a 4000' mountain. Those stations often have only a few dB noise margin and don't even appear on my TV Fool report which bottoms out at -34 dB! That would equivalent to you trying to receive WPCH. Any station on my report with at least a 0 dB NM is a piece of cake to receive.

If you have trouble with reception of your stronger stations it will most likely be because you're looking through trees which are particularly destructive on UHF, not because the signals are too weak.

Finally, your FM Fool report doesn't show any very strong stations so I wouldn't worry about that issue.

Whatever you decide to do, please report back and let us know what happened.
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Old 01-10-2015, 10:24 AM - Thread Starter
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Quote:
Originally Posted by Calaveras View Post
Knox and Chatt are almost in opposite directions for you. I doubt that adjusting the DB8e so that the halves point in opposite directions is going to work. This is the same as having two different antennas pointed in opposite directions and combining them through a 2-way splitter. In many cases this simply creates multipath issues. Also the Knox stations are very weak and you need a good antenna pointed in one direction for them.
Can you provide me with or link to more info on this? If it is a bi-directional antenna, why would the positioning of either matter that much?

It looks like my two best options are:

-7698 w/ rotor

-DB8e w/ Y10713 and possible rotor.

If I'm really going to have trouble with the DB8e and pointing in 150+ degree opposite directions, then maybe that isn't the best choice. But, I do love the form factor of it and future possibility of easier attic-mounting.

If I only expect a 2-3 year lifespan for my rotor, would the Antennacraft/RadioShack TDP2 at least be respectable for that amount of time? This isn't going to be a decade-long solution for me.

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Old 01-10-2015, 11:38 AM
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Quote:
Originally Posted by Calaveras View Post
The Noise Margins in TV Fool are based on a 0 dB gain antenna. With the 7698 and a mast mounted preamp you can expect roughly a 20 dB increase in Noise Margin over the TV Fool numbers. That would put your noise margins in the 40's. That's very good. The DB8e has a couple dB more gain than the UHF portion of the 7698. It won't make any difference if a particular station is +40 dB or +42 dB. I think you'll find that the 7698 or HBU55 is more convenient.
That's not quite correct....Noise Margin (NM) is the amount of EXCESS Gain presuming an idealized Dipole Antenna with 0 dBd=2.2 dBi Gain and ZERO Loss between Antenna and TV Tuner, which is presumed to have a "typical" internal Noise Figure [In our many discussions, I don't remember off-hand what stan.s.lee presumed, probably 5-6 dB, so presumed IDEALIZED System NF = 5 to 6 dB.] BTW: At NM = 0 dB, the associated F[50,90] "reliability" statistics are 50% of similar locations for 90% of the time.....which means you have a 50/50 chance of barely getting the station long enough to recognize that a program is playing, but you wouldn't want to watch it for any length of time....
https://www.tvfool.com/index.php?opt...57#how_to_read

So for DB-8e with Gain = 14.7 to 17.4 dBi from Ch14-51, Gain = 12.5 to 15.2 dBd [Not sure exactly HOW much Gain is provided by HD7698P...a LOT Less on the lower channels]. Without a Preamp, the System Noise Figure depends on the total Loss plus Tuner NF and may typically range from SNF = 10 to 20+ dB, depending on Cable Lengths and number of Splitter Drops. [This would completely CANCEL the Antenna Gain.] WITH a Mast Mounted Preamp, System Noise Figure is typically in the ballpark of 2-4 dB [slightly better than directly connected TV Tuner, see my Spread Sheet Calculator], yielding a "Fade Margin" = NM + Antenna Gain - SNF, which would be in the ballpark of 10 dB [NOT 20 dB] more than the calculated NM. For year round RELIABILITY, I like to see a Fade Margin of 10 to preferably 20 dB for 1Edge and 2Edge paths, esp. since TVFool does NOT include any and all factors that affect reception.

And with a Distribution Amplifier, SUBTRACT Antenna to DistroAmp Coax Loss from the Antenna Gain, perhaps another 3-7 dB Loss. I do NOT recommend using BOTH a Mast Mounted Preamp and a DistroAmp unless the signals levels have been carefully Calculated and MEASURED with Attenuators inserted as necessary to Maximize the Spurious Free Dynamic Range (search for my "SFDR" posts):
http://imageevent.com/holl_ands/files/ota [System Noise Figure Calculator is Item #10 .]

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Old 01-10-2015, 11:49 AM
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I once asked stan.s.lee about noise margin and he said that it used the SNR at the antenna assuming an ambient noise temp at around 275 Deg k which puts the Noise Figure at about 2.9 dB.
John
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Old 01-10-2015, 12:07 PM
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When the 4-Bays in the DB-8e point in widely different directions, the Gain drops off quite a bit, equivalent to having two lower Gain DB-4e's Back-To-Back [preferably feeding an A/B Switch to minimize Loss and Multipath]:
https://www.antennasdirect.com/cmss_...s/DB8E-TDS.pdf
Sorry, I've pestered A-D to improve the readability of their charts, but so far no joy....see the last chart.

BUT, to pick up the very weak stations in the other direction, you need as much Gain as possible...which means using a DB-8E with a Rotator.

The EXTREMELY STRONG FM Station signal levels I reported on above were found at the Zipcode location (25-ft high) only 0.1-mi away from the location (20-ft high) assumed in your FM Report posted above....yet there was nearly 20 dB difference between them....very curious. So don't ASSUME you won't have FM Interference problems....check carefully and if NEEDED you can insert an FM FULL BAND FILTER.

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Old 01-10-2015, 12:12 PM
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Quote:
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I once asked stan.s.lee about noise margin and he said that it used the SNR at the antenna assuming an ambient noise temp at around 275 Deg k which puts the Noise Figure at about 2.9 dB.
John
OK....and I've gone back and forth with him [comparing to my earlier efforts using Radio Mobile PPP] as to whether his numbers correspond to either dBi or dBd....whatever...it's all in the same ballpark given the inaccuracy of the underlying Longley-Rice PPP (Propagation Prediction Program)....at least the use of dBd vice dBi narrows the Gap between assuming the use of a Preamp with SNF=2.9 vs a direct connected Tuner with SNF=5-6 dB.

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Old 01-10-2015, 12:17 PM - Thread Starter
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Originally Posted by holl_ands View Post
When the 4-Bays in the DB-8e point in widely different directions, the Gain drops off quite a bit, equivalent to having two lower Gain DB-4e's Back-To-Back [preferably feeding an A/B Switch]:
https://www.antennasdirect.com/cmss_...s/DB8E-TDS.pdf
Sorry, I've pestered A-D to improve the readability of their charts, but so far no joy....see the last chart.

To pick up the very weak stations in the other direction, you need as much Gain as possible...which means using a Rotator.
ok this makes sense. rotation will be required if i want both cities. In your graphs, are you assuming all 4 bays pointed at 90 in the "0 degrees off broadside"? 180 and 0 for "90 degrees off broadside"?

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Old 01-10-2015, 04:19 PM - Thread Starter
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here's the view towards Chatt. 247 is essentially directly in line with the ridge of the neighbor. my ridge (where this photo was taken) is right at 20ft. looks like i need to go to at least the 25ft mark.


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Old 01-10-2015, 05:49 PM
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For Maximum Gain, both 4-Bays are pointed in the SAME direction, so their Bowties are aligned in the SAME Plane.
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Old 01-10-2015, 06:18 PM - Thread Starter
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so I've got a vote for the 7698P and a vote for the DB8e with a Y10713?

It looks like the most cost effective is going to be the 7698P. I can get the antenna itself for $121 shipped. I might just pass on the rotor for right now and possibly fool with that in a few months if I feel up to it.

The HBU55 would be right at $100 total, though, and available through Radio Shack (easy return if there's an issue)

What's the consensus on the 7698P vs the HBU55?

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Old 01-10-2015, 08:48 PM
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Can you provide me with or link to more info on this? If it is a bi-directional antenna, why would the positioning of either matter that much?

The part of the antenna pointed opposite the station receives whatever signal is coming from reflections. This can vary from almost nothing at all if you live on the plains with few buildings around to a big signal reflected by mountains. Depending on how large the signal is, the reflected signal which is summed in with the main signal can reduce the Signal-to-Noise to where the station cannot be decoded. The situation is worse in an attic or indoors because the inside of the building produces reflections. There's no real predicting when this will work and when it won't. You just have to try it. I prefer not to recommend potential failures here on the forums.
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Old 01-10-2015, 08:52 PM
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Originally Posted by ctdish View Post
I once asked stan.s.lee about noise margin and he said that it used the SNR at the antenna assuming an ambient noise temp at around 275 Deg k which puts the Noise Figure at about 2.9 dB.
John
Is any of this spelled out anywhere so we don't have to take guesses?
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Old 01-10-2015, 08:57 PM
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Originally Posted by mrredskin View Post
so I've got a vote for the 7698P and a vote for the DB8e with a Y10713?

It looks like the most cost effective is going to be the 7698P. I can get the antenna itself for $121 shipped. I might just pass on the rotor for right now and possibly fool with that in a few months if I feel up to it.

The HBU55 would be right at $100 total, though, and available through Radio Shack (easy return if there's an issue)

What's the consensus on the 7698P vs the HBU55?

If you mount where you can get to it you can turn it manually for a test and see if a rotor is worth it.

I'll bet the difference between the two antennas is small.
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Old 01-11-2015, 09:49 AM - Thread Starter
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HBU55 is purchased.

Initial split will be to a living room tv and a silicondust HDHomeRunPrime tuner/PC. Possibly to a 2nd tv in future but not yet. 7778 still recommended?

Last edited by mrredskin; 01-11-2015 at 09:53 AM.
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Old 01-18-2015, 04:39 PM - Thread Starter
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just did a test on my old tailgating mast pointed in the general direction of Chattanooga with new hbu55. didn't level it either. back yard clear of neighbor's house and most trees. pulled in at least 14 channels including WBIR 10 from KNOXVILLE!
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Old 01-18-2015, 04:40 PM - Thread Starter
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this is a 50ft straight to TV thru house.
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