The Official AVS Antenna and Related Hardware Topic! - Page 510

Thanks for the compliment, Tyler.

I've tried several pre-amps here, but none of them can handle the signals I get from Sutro Tower, just 3/4 of a mile away. TVFool shows the Noise Margin from the 11 stations up there to be from 89 to 78 dB. I have about 70 feet of coax on the antennas, so a preamp would probably help for the distant stations, but no such luck. The distribution amp gives me a +1 dB gain over the input from the antennas, but I could use a few dB more!

I haven't tried the new version of the 4228. From what I've heard it's not as good as these originals that I'm using.

Larry
SF

Ahhhh. Nothing more beautiful than the sight of an aluminum forest. Nice Larry. My Grandmother lived in the Mission District back in the 60s and 70s. I lived in Silicon Valley, so know SF Bay Area well.

Diplexer vrs splitter, I am hooking up an HD homerun Dual and Sony 720 TV to the same OTA antenna, I was told not to get a splitter, use a diplexer. Can anyone recommend a specific brand/etailer for the diplexer? (Note for the splitter Silicondust's documentation recommends 5-1000 MZ only)
Edited by Josea - 3/12/13 at 8:09am

Yes, absolutely, if in a strong signal area. Think of wearing a hearing aid to a rock concert... If you don't need one, then it's only going to harm the experience.


Maybe, but you'd still have to prevent with the above issue. If there are signals just below the tuner's reception threshold, then an amp can help lift hem up out of the background enough so they're usable, but you still have to avoid amplifying strong signals that would overload or distort. If you happen to be in an area where there are no really strong signals, then the amp may well give you better performance out of the system.

I recently installed an Antenna Direct DB8 outdoors and am having some difficulty with pixalation on channels 5.1 and 11.1. Moving the antenna around to test now but wonder based on the TV fool link below, should I have a different antenna and if so, which on please and thanks. I am surprised because I am so close to the stations?

Jay
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1ddad8e9ceba05

My guess would be that the picture break-up is caused by signal bouncing off things, like moving traffic.
Are you close to a major road?
Proximity to the transmitters could hurt more than help if you are dealing with multipath.
I'd like to know the surrounding conditions more before suggesting you have too much antenna.

Your signals are extremely strong. The first two listed have the dBm pwr in red which indicates possibility of overload. Try an attenuator in series with the antenna coax coming to the tuner to see if that helps. If it does, leave it in and/or try an RCA ANT751 which is a small antenna for strong signal areas.

Your coax should be grounded with a grounding block in such a strong signal area. It also should be grounded to comply with NEC safety requirements.
Edited by rabbit73 - 3/12/13 at 12:57pm

The hoverman can be scaled to any frequency you want. The size is inversly proportional to frequency and directly proportional to wavelength. A hoverman for your frequency range would be about half the size of a hoverman for UHF TV. What advantage do you think the hoverman would give you over the yagi?

Nothing wrong with thinking outside the box; that's how new inventions are created!

It's funny - I originally thought my close proximity was a plus but agree that being 4 miles or so away seems to make the alignment most critical. I have mounted the antenna outdoors, on the roof, about 22 feet up. It is facing many mature trees most of which don't have leaves right now (other than a few pines which are still green). No roads other than local. I moved the antenna a bit last night and improved the signal on 5.1 and 11.1 but degraded 17.1 and a few others. Gonna try again tonight and take some notes.

Appreciate your help!

Jay

You want a splitter. A splitter simply divides the signal 2 ways, 4 ways, etc. with corresponding loss. A diplexer divides/combines frequency bands such as VHF and UHF with little loss. A diplexer would be used to combine separate VHF and UHF antennas onto one coax. A splitter is used to divide the signal to go to 2 or more TVs.

Chuck

Nobody noted that 11.1 is on RF 10 which is VHF and you are using a UHF antenna. It's true your signals are very strong and some people get away with using the wrong antenna in this situation but others don't. I'd recommend one of the smaller antennas in the Winegard HD769xP series that is designed for VHF and UHF. I'm betting your channel 11 problem will go away with the correct antenna.

In regards to multipath, reflections can affect any strength signals. I'm 54 miles from the transmitters and have major issues with multipath. Pixelation simply means the signal-to-noise of your station is close to the minimum. It doesn't necessarily mean your signals are weak. Certainly they're not in your case.

I assume you are not using a preamp or distribution amp? You don't need one and it would be detrimental with such strong signals. Adding a 20 dB attenuator might be an interesting test.

Do you actually have line of sight to the transmitters from your antenna? Trees can be a problem but with no leaves they should not be. How many pine trees are there? Moving trees can cause problems. I set up an antenna once that looked through a line of eucalyptus trees which were the only things blocking LOS. One station was severely affected with its signal strength jumping all over the place. Other stations were less affected. This was only about 15 miles from the transmitters.

If your antenna is sensitive to position then you have some sort of multipath issue going on which is hard to troubleshoot over a forum.

Chuck

Jay:

Calaveras is right about channel 11.1, which is on RF10. You're using a UHF-only antenna (albeit a very good one), which won't resonate well at VHF-high frequencies. Cheapest/quickest solution is to add a Y5-7-13 VHF-high antenna a foot or two below your DB8 on the same mast, and join it with your DB8 using two short (3-4-foot) RG-6 coax pieces fed into a UVSJ up at the mast, with a single RG-6 coax fed down from there to your tv. Also, as Calaveras said, if you're using any kind of distribution amp to split your signal to multiple tv's, take it out and replace it with a simple splitter, since you're too close to your transmitters for any amplification.

http://www.solidsignal.com/pview.asp?p=y5-7-13
http://www.solidsignal.com/pview.asp?p=uvsj

With at least one VHF-high station in your area, the DB8 wasn't really the right choice for you, even though it's a very good UHF antenna. It's way more powerful than you need at such close range, and UHF-only. Presuming that it can't be returned since it's been outside, if you wanted to sell it to someone who needs a longer-range UHF antenna, you could switch to the RCA ANT751 or Winegard HD1080, both of which cover both UHF and VHF-high, in a smaller size.

http://www.solidsignal.com/pview.asp?mc=03&p=ANT751
http://www.solidsignal.com/pview.asp?p=HD-1080
Edited by gcd0865 - 3/13/13 at 11:42am

Agree with Calaveras. Your signals are very strong and they may be overloading the RF amplifier in your TV. The amplifier may work well with the sum of the average power but occasionally you will get a peak power that the amplifier overloads on. An attenuator or a less sensitive antenna may be the solution.

OK I am ready to put up an outdoor antenna. I am in Philadelphia, PA. Tired of the dropouts from the indoor one. I went to TV Fool and here is the link:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1dda5004eeb500

If I can get the top 12 channels I will be very happy. As to the inside situation, I would want to drive 2 HTPC's each with a dual tuner card, and 2 FM receivers. Can any kind soul suggest an antenna (and any other equipment I would need) for my situation? I don't really see needing an amp, but I do want to split the signal a bit.

Thanks in advance
Edited by Richardw322 - 3/17/13 at 9:21am

A small, all channel antenna should work fine. Aim it at Roxborough. You could probably cheat and use a small U/Hi-V antenna like the C2V and get away with it since WPVI uses enough power that a half or third-size dipole should still work well enough.

At 8 miles distance, something relatively small should work just fine. With WPVI being on channel 6, you'd want an antenna capable of VHF-low reception, in addition to VHF-high and UHF. One inexpensive possibility might be the Antennacraft AC9:

http://www.solidsignal.com/pview.asp?p=AC9
http://www.radioshack.com/product/index.jsp?productId=11113388

Try first with no amp, just using a regular splitter to feed your various tuners.

FYI DIY'ers:

In response to a query re a better Ch12 Yagi Antenna, I conducted a series of 4nec2
analysis runs after using nikiml's Python Optimization Scripts, see discussion thread:
http://www.digitalhome.ca/forum/showthread.php?t=161018

Complete 4nec2 Analyses found here:

Ch12 12-Element Folded Dipole Yagi (two Boom Lengths):
http://imageevent.com/holl_ands/yagis/ch1212elfdyagiopt

Ch13 12-Element Folded Dipole Yagi:
http://imageevent.com/holl_ands/yagis/ch1312elfdyagiopt

Hi-VHF (Ch7-13) 12-Element Folded Dipole Yagi
http://imageevent.com/holl_ands/yagis/hivhf12elfdyagiopt

Hi-VHF 12-El FD-Yagi (Boom Length=107-in) provides significantly higher Raw Gain,
F/B & F/R Ratio performance and lower SWR than either the Winegard YA-1713
(10-El, Boom Length=99-in) or Antennacraft Y-10-7-13 (10-El, Boom Length=117-in):
http://imageevent.com/holl_ands/logyagi


Even more Yagis found here:
http://imageevent.com/holl_ands/yagis


FYI: Link to nikiml's webpage for Python Script download & other info:
http://clients.teksavvy.com/~nickm/scripts.html
Edited by holl_ands - 3/18/13 at 10:13pm

Would it be overkill to go with the Aantennacraft 5884 Colorking? I would rather overbuild a bit than have to go up and replace it. 12 bucks more for insurance. I just worry it would kill input amps.

gcd0865, actually the DB8 will cover VHF-Hi (7-13), and UHF, which it was designed for.

I almost think you could get away with the basic unamped rabbit ears and loop from Radioshack at your location, with such strong signals. Or perhaps step up to a Terk HDTVi. Also consider multipath as a problem. And 11 Alive is one of the stronger HiVHF channels on RF10, so you should not have a problem with receiving the signal. And the techs at Dow Electronics off Boggs Rd recommend the similar Channel Master 4228HD antenna for the Atlanta area. Although optimized for UHF, it does receive HiVHF including WXIA-11 and PBS Channel 8 based upon their reports.

Richardw322:

The Antennacraft 5884 should also work fine in your area. Being 8 miles from many full-power transmitters, you will not likely be able to use any kind of amplifier up at the antenna mast, although you might be able to use a distribution amplifier at some location inside your house (away from the antenna) if signal strength to your multiple tuners ends up weak due to splitting.

Gregzoll:

I was always under the impression that, among the various 4-bay and 8-bay type UHF antennas, only the 8-bay versions with continuous-width reflector screens (such as the old CM4228A and the newer CM4228HD) would receive VHF-high channels 7-13 decently, because the continuous screen width (of maybe 35"-40") was wide enough to resonate on VHF-high frequencies. All reports I saw seemed to indicate that since the DB8's reflector screen was separated, and not continuous, in its width, VHF-high performance would be poor on the DB8. Of course, at locations very close to the transmitters, even antennas that don't resonate well on certain frequencies will provide adequate reception, simply by virtue of strong signals.

As an example, see this comparison: http://www.antennahacks.com/Comparisons/N-Bay_VHF_Shootout.htm

If this information doesn't properly reflect real-world reception, though, I'd certainly stand corrected.

Thanks, I'll give the 5884 a shot.

Our Channel 13 transmitter for Channel 49.x is about 8 miles away, but even with just the amp, and the DB8 aimed that direction of the tower, you could get 74% for reception. It actually works great for VHF-hi, but you have to have a rotor to be able to tune in towers from other directions. I use a combo of a VHF-Hi for just the one channel (13), and the DB8 for everything else. Have a Channel Master CM-7779 Pre-amp.

I can tell you this, just like in the past, Not all antennas were created equal, and all they have done with today's models, is just tweaked them a little, but overall, they are really the same units as have been used for the past 60 years.

This business about using the wrong antenna for the job is just a matter of how bad the antenna performance is on the frequency it's not designed for and how strong is the signal to be received. If the combination is good enough the station can be received assuming noise and/or multipath is not also an issue. I receive an LP station on RF channel 3 using an FM antenna but it works best off pointed 45 degrees. The pattern at 57 MHz is all messed up.

I know someone who was able to receive all his local stations (VHF and UHF) at 40 miles distance with a dipole antenna made out of aluminum foil stuck on the back of his TV. But those sorts of people never come to a forum like this because they aren't having problems. We only get the people who are having problems or people who are starting from scratch with no antenna. I don't feel it's responsible to tell people who come here to try an antenna that's not designed for the channel(s) they want to receive just because the proper one is a little larger or more expensive than they had in mind. Better they get something that works even if it's a little larger than required than something that doesn't work.

Chuck

You are no doubt essentially correct, Chuck.. But there is a risk in recommending anything when you can't get your own hands on things.
A Log Periodic or Yagi generally gives good gain and is usually quite directional. They have to be aimed well. Stacked bowties aren't as directional.
I favor the bowties, and have since analog times. 30 years ago I used a 6 bowrie array that worked as good as anything else I had tried. It was useless for weak Low Band VHF, but I didn't have any of those to worry with. I think I developed a prejudice.
I'm using a 4 bay now, and I do not think I can expect better results from another design. I have no transmitters closer than 32 miles from me, and the available stations are in several directions. To receive the one High Band VHF station I have any prayer of getting, I have to do an approximate point at it. But I think that is something that would be required with any antenna. It is almost 45 ,miles away.. But, I do not have to reposition the antenna to receive the UHF stations, some of which are 50 miles distant.
I like the convenience of not having to reposition the antenna frequently.
Despite that, I'm sure a large Log Periodic type antenna would be best for a lot of people. That is, if the person using it were willing to accept using a rotor that may or may not be as good a the ones made 25 years ago, and, willing to accept the need to use it often.or have multiple, dedicated antennas.

Just a comment on your "A Log Periodic or Yagi generally gives good gain and is usually quite directional." The directional characteristic results from higher gain; that is how the gain is acheived.

Higher Gain can be achieved by reducing Beamwidth in EITHER or BOTH Horizontal and Vertical dimensions.
Stacking Bowties increases Gain by reducing Elevation Beamwidth, leaving a fairly broad Azimuthal Beamwidth,
as evidenced by the Vertically Stacked 8-Bay (without Reflector)...but when you add the VM8's Double-Angled
Reflector, it adds additional Gain by narrowing the Azimuthal Beamwidth, so Beamwidth is about same as 91XG:
http://m4antenna.eastmasonvilleweather.com/Computer%20models/Computer%20models%20M8.html
Edited by holl_ands - 3/22/13 at 7:42pm

I think maybe you mean the directional characteristic results in higher gain ; Is that correct? I would not wish to misunderstand..

Gain and directionality are interlinked.

Think of how a MagLite works, for example. The brightest beam (highest gain) occurs when it is the most focused (most directional) while the weakest, widest beam is when it is the least focused.