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San Francisco, CA - OTA - Page 308

post #9211 of 10428
Quote:
Originally Posted by Trip in VA View Post

Don't get confused by KQEH. They're operating an antenna that looks like this:

http://www.rabbitears.info/pattern.php?request=ant_pat&ant_id=85202&rotation=0&erp=310

- Trip

Thanks Trip. I see what's going on. Where does it say there is 1 degree of mechanical down tilt? I can't find it. And if the antenna has 1 degree of mechanical down tilt at 225 degrees azimuth, does that mean it has 1 degree of up tilt in the opposite direction? I'm at 57 degrees azimuth from that antenna, essentially the opposite direction. So if there's 1 degree of mechanical up tilt and 1 degree of electrical down tilt, that should mean there's 0 degrees of tilt in my direction. At 90 miles and 2650 feet I guess I'd be at the horizon. If I use the horizontal and vertical patterns in the antenna document I'd have this?

310*.317*.317*.65*.65 = 13.2 KW

Do you agree with that?

Chuck
post #9212 of 10428
Quote:
Originally Posted by Calaveras View Post

Thanks Trip. I see what's going on. Where does it say there is 1 degree of mechanical down tilt? I can't find it.

Well, it's listed on RabbitEars, for one. Otherwise, it's in the application, Section VII, number 10: http://licensing.fcc.gov/cgi-bin/ws.exe/prod/cdbs/forms/prod/prefill_and_display.pl?Application_id=1429731&Service=DT&Form_id=340&Facility_id=35663
Quote:
And if the antenna has 1 degree of mechanical down tilt at 225 degrees azimuth, does that mean it has 1 degree of up tilt in the opposite direction? I'm at 57 degrees azimuth from that antenna, essentially the opposite direction. So if there's 1 degree of mechanical up tilt and 1 degree of electrical down tilt, that should mean there's 0 degrees of tilt in my direction.

Sounds right.
Quote:
At 90 miles and 2650 feet I guess I'd be at the horizon. If I use the horizontal and vertical patterns in the antenna document I'd have this?

310*.317*.317*.65*.65 = 13.2 KW

Do you agree with that?

Chuck

It has 1 degree of electrical tilt, which means the "1" field value is at 1 degree below horizontal. So if you have a 1-degree up-tilt, which you do, that cancels out the 1 degree electrical meaning the "1" value is now at 0 degrees, so it would look like:

310*1*1*.317*.317 = 31.15 kW

- Trip
post #9213 of 10428

Where did this link come from? I'd like to be able to find these antenna documents for any station.

Chuck
post #9214 of 10428
You can't, unfortunately. It came from the bottom of the application I linked you in my latest post. You have to depend on the station, and the FCC, making it available.

- Trip
post #9215 of 10428
I have to start using Rabbit Ears more. smile.gif It is easier to find things by far.

Okay on the antenna documents. I was afraid of that. At least the applications are available.

Figuring out ERP of distant stations in your direction when you don't have LOS and the curvature of the Earth comes into play is difficult if not nearly impossible which probably explains why TVFool predictions in those cases are highly inaccurate.

Chuck
post #9216 of 10428
Which would be more stable in high winds...
A antenna on a 1 1/2"x10' mast on a 5' tri pod with guide wires or the same mast on a chimney mount?
post #9217 of 10428
Quote:
Originally Posted by ellisr63 View Post

Which would be more stable in high winds...
A antenna on a 1 1/2"x10' mast on a 5' tri pod with guide wires or the same mast on a chimney mount?

I think it would definitely be the tripod. That's how my antennas have been mounted and guyed for years and I've never had a problem.

Larry
SF
post #9218 of 10428
KGO DTV has been really unreliable since around late january down here in coyote valley, so before dropping the money on a new vhf antenna that may or may not improve see improved reception, i decided to give KGO LD one last chance.

my set up is a bit of an involved one because im in a townhouse (no access for a roof mount) almost 60 miles from sutro, and while im only 20 miles from mt allison it is 2 edge (we're right at the foot of the diablo range) making reception tricky. long story short, either side of the attic is better suited to reception to each set of towers.

the side best suited to reception from sf is very crowded with framing and ducting so i put the clearstream 4 there and i can pick up every non LP/LD station (even VHF KNTV) from sf except KGODT. its been there for about a year now and reception has been very reliable from sutro/san bruno even during the difficult summer conditions.

on the side that picks up the mt allison signals better, i have my 91xg mounted, which is also very tricky to adjust b/c of its size and the the truss framing, but after removing my clearstream 5 that i was using to try and pick up KGODT, enough room was created to tweek it JUST enough to pick up KGOLD with SS in the low to upper 40s, SQ from the low 50s to mid 60s. def'ly not optimal, but thus far its been steady and reliable. and *knock on wood* since we're much closer to those transmitters there is much less variation in conditions like there are over the bay. as an added bonus even KTVU-LD and KAXT will come in from time to time.


removing the cs5 and adjusting the 91xg to the north did sacrifice reception from sf, which would make recording shows kind of pain: if you only have one tuner input to record from like with a tivo then, you'd have to choose with channels were your priority, or you'd have to know what youre doing when it comes to combining uhf signals. that or you have a rotor, which if you leave it in the wrong spot, your recording will be a "searching for signal" graphic.

but since i have 2 homerun hd tuners (the old blue single tuner model, and the really nice new dual tuner) each tuner input has its own antenna, and then i can go into windows media center and assign each channel in the guide to its respective tuner. et voila, nobody has to miss a show.

the moral of the story being, for those of us who are in a multi-antenna situation, a set up along the lines of whats described above might be worth the trouble
Edited by CTEL08 - 3/13/13 at 12:44pm
post #9219 of 10428
Question. If you run 2 antennas... Wouldn't it be possible to inject the channels from each antenna to a single coax feed ? I would think that there would be a way to filter out the channels from each antenna that you don't want. Or am I dreaming?
post #9220 of 10428
Quote:
Originally Posted by ellisr63 View Post

Question. If you run 2 antennas... Wouldn't it be possible to inject the channels from each antenna to a single coax feed ? I would think that there would be a way to filter out the channels from each antenna that you don't want. Or am I dreaming?

Our antenna experts, and we have several, will pop in in a minute or two. There is a gizmo called a 'combiner' that will do what you want. You take two antenna feeds in and one coax out.... The gurus will tell you how it all works.
post #9221 of 10428
Quote:
Originally Posted by bobby94928 View Post

Our antenna experts, and we have several, will pop in in a minute or two. There is a gizmo called a 'combiner' that will do what you want. You take two antenna feeds in and one coax out.... The gurus will tell you how it all works.

That is what I was thinking... I remember years ago using one to inject my HD channels to my DTV feed. It worked perfectly but I was not sure if it would work for 2 antennas that are in the same bandwdth. It would be nice because you could pick what channels you wanted off of each antenna.
post #9222 of 10428
Quote:
Originally Posted by ellisr63 View Post

Quote:
Originally Posted by bobby94928 View Post

Our antenna experts, and we have several, will pop in in a minute or two. There is a gizmo called a 'combiner' that will do what you want. You take two antenna feeds in and one coax out.... The gurus will tell you how it all works.

That is what I was thinking... I remember years ago using one to inject my HD channels to my DTV feed. It worked perfectly but I was not sure if it would work for 2 antennas that are in the same bandwdth. It would be nice because you could pick what channels you wanted off of each antenna.

In a busy RF area like SF Bay area, a simple combiner is out of the question. weak signals from the back side of one antenna will act like multi-path when combined with the strong signals from the other antenna.

If you only want one or two channels from one antenna, you can get something called a "jointenna", but this will destroy any channel adjacent to the channel you are trying to add (from either antenna). One can not build a filter that completely blocks one channel, and completely passes an adjacent channel. It usually takes a full 6 MHz channel bandwidth to transition from pass band to stop band.

I think the only way to deal with this properly is to have a tuner on each channel of each antenna you wish to receive that decodes the data to a digital streams, then re-modulate them and combine the resulting single channel signals. This would allow you to deal with the wildly varying signal strengths & signal directions. This would not be cost effective.

I have two antennas at my house, my solution is a HDHomeRun attached to each antenna, and MythTV.
post #9223 of 10428
Quote:
Originally Posted by ellisr63 View Post

Question. If you run 2 antennas... Wouldn't it be possible to inject the channels from each antenna to a single coax feed ? I would think that there would be a way to filter out the channels from each antenna that you don't want. Or am I dreaming?

It can be done in commercial antenna systems.... Like hotels or Comcast .... (Expect to pay $500+ for each channel filtering equipment) For simple residential antennas with cost, and electricity use a factor, No.
Do you like math ? ..eek.gif.. Everything that works..... has a math formula. ..... Here's why It wont work.

Antenna # 1 VHF antenna (5db forward gain)... west to San Francisco
Antenna # 2 VHF antenna (5db forward gain)... east to Sacramento

Any VHF channel, math formula for above +5 gain ....(direct signal)
- 5 gain ....(multipath signal in front of this antenna)
= 0 no signal ...... signal gains cancelled out

Example # 2

Antenna # 1 VHF only antenna (5db gain)
Antenna # 2 UHF only antenna (5db gain)

With the above system the math is .... + 5db gain UHF
+ 5db gain VHF
= 5db gain VHF & UHF (antennas in any direction)

So the below #2 example works, .... the first one does not.
post #9224 of 10428
You can connect a VHF antenna and a UHF antenna into one coax using a combiner, but not two antennas for the same band. I've tried it with several different methods and different antennas, even using a splitter backward, and in all cases the results were bad. All signals were down or a lot worse than when the antenna was connected by itself.

I ended up buying two A-B-C RF switches... which allow three coax cables to be connected and you select the one you want to go to the output. Since I have five antennas I took the output of the first switch with three antennas and put it into one of the inputs of the other switch along with the other two antennas. With the right buttons pushed you can select any one of the five antennas. The output of the switches is connected to the input to the TV tuner. This set up has been working fine for several years. The switches don't make any noticeable decrease in signal strength.

I have one antenna, a VHF/UHF combination antenna, that is locked down, set to receive all the local channels from Sutro Tower, Mt. San Bruno and the South Bay. I have it connected direct to the DVR without going through any of the switches. That way I don't have to worry about having any of the other antennas pointed in the right direction for my daily recordings.

If you want to see my antennas, take a look here: http://www.larrykenney.com/tvantennas.html

Larry
post #9225 of 10428
Quote:
Originally Posted by ellisr63 View Post

Question. If you run 2 antennas... Wouldn't it be possible to inject the channels from each antenna to a single coax feed ? I would think that there would be a way to filter out the channels from each antenna that you don't want. Or am I dreaming?

I assume you're asking about combining an antenna pointed to Walnut Grove and another pointed to SF. What you've been told is correct. You cannot combine two identical antennas with a simple combiner because the signals will interfere with each other. Single adjacent channel filtering is expensive for one channel let alone all the ones you need. These options are out. Your choices are separate downleads with an A/B switch or a rotor.

Chuck
post #9226 of 10428
There, the gurus have spoken, and I was incorrect. smile.gif Listen to what they tell you...
post #9227 of 10428
Quote:
Originally Posted by ellisr63 View Post

That is what I was thinking... I remember years ago using one to inject my HD channels to my DTV feed. It worked perfectly but I was not sure if it would work for 2 antennas that are in the same bandwdth. It would be nice because you could pick what channels you wanted off of each antenna.

Why would anyone not want to include all available channels? As soon as you delete one channel from your available list, the programming on that channel could change.
post #9228 of 10428
Quote:
Originally Posted by rdvegas View Post

Why would anyone not want to include all available channels? As soon as you delete one channel from your available list, the programming on that channel could change.
The intent was to be able to get all the channels I want... ie. if NBC from SF was a strong signal and the Sacramento signal was weak, I would block the Sac signal for that station. If I end up running 2 antennas then it is harder to record shows unless I use 2 tuners.
post #9229 of 10428
The antenna that I used with my laptop when traveling fell apart, so I ordered the Mohu Leaf from Amazon. I've seen a lot of good reports about it and now I've been very pleased at how well it works. For such a small, thin piece of plastic, it's really amazing. It's just 9 by 11-1/2 inches and about the thickness of a credit card.

From my home here in San Francisco I can receive all of the stations from Sutro Tower (of course), all the full power ones from Mt. San Bruno and Monument Peak/Mt. Allison, plus 42 from Mt. Diablo, 68 from Novato and 22 from Rohnert Park. I can see signals from the low power stations on Mt. San Bruno and from KEMO on Mt. St. Helena just below the cliff edge. Not bad, eh?

For anyone that needs an indoor antenna, I highly recommend the Leaf. They also make the Ultimate Leaf that has a preamp, too. No word on how that works.

Larry
post #9230 of 10428
Quote:
Originally Posted by Larry Kenney View Post

The antenna that I used with my laptop when traveling fell apart, so I ordered the Mohu Leaf from Amazon. I've seen a lot of good reports about it and now I've been very pleased at how well it works. For such a small, thin piece of plastic, it's really amazing. It's just 9 by 11-1/2 inches and about the thickness of a credit card.

From my home here in San Francisco I can receive all of the stations from Sutro Tower (of course), all the full power ones from Mt. San Bruno and Monument Peak/Mt. Allison, plus 42 from Mt. Diablo, 68 from Novato and 22 from Rohnert Park. I can see signals from the low power stations on Mt. San Bruno and from KEMO on Mt. St. Helena just below the cliff edge. Not bad, eh?

For anyone that needs an indoor antenna, I highly recommend the Leaf. They also make the Ultimate Leaf that has a preamp, too. No word on how that works.

Larry

When I looked at their website, I saw that they have the Leaf Plus as the amplified version on the antenna. The difference with the Ultimate was that the Ultimate can be connected directly to the television so that it only uses electricity when the television is on. It has an addition cable. The description of the amp said that it helps with signals you want, and helps with signals you don't want. That sounds good, but I don't have one to confirm. They are also offering the amp alone.

Are you receiving signals that TVFool lists in the yellow category? Also, did the Leaf come with a cable attached. Last year, mine did. No antenna should come with a cable attached.
post #9231 of 10428
The Leaf Ultimate has a newer and improved amp with lower noise figure and clean signal filtering. Also Winegard now has an amped Flatwave that is similar, and sold at Costco. Winegard also sells their LNA-100 Boost amp separately, which is similar to Mohu Jolt but a bit more power. If you want to connect your own cable length, then select the HD Blade from Solid Signal. It is the same as Winegard Flatwave, but without the cable attached. And you can order the Boost amp separately if needed, or use any other good dist amp.
post #9232 of 10428
Quote:
Originally Posted by deltaguy View Post

Are you receiving signals that TVFool lists in the yellow category? Also, did the Leaf come with a cable attached. Last year, mine did. No antenna should come with a cable attached.
With my new Leaf I'm able to receive all of the stations listed in the yellow section of the TVFool list except one, plus I get three stations in the pink section.

My Leaf came with a coax cable but it wasn't attached. There is an F-connector on the antenna where the coax connects.

Larry
SF
post #9233 of 10428
Well we got the antennae installed today... We ended up pointing toward Sacramento (around 51-54 degrees). We tried San Francisco channels but we could only get 5 channels of which 2 would be watched by us. By going toward Sacramento we got all 4 network channels and several others that we will watch. Strange thing was channel 9... It had a strong signal but the channel was blank. Channel 9 was one of the channels we would watch and it had the signal maxed when the antenna was pointing around 241 degrees.

Right now our weakest channel is Fox with a 3 on the signal strength and the other networks were 8-10. We will see how the weather effects them now.

Thanks for all the help!
post #9234 of 10428
Quote:
Originally Posted by ellisr63 View Post

Strange thing was channel 9... It had a strong signal but the channel was blank. Channel 9 was one of the channels we would watch and it had the signal maxed when the antenna was pointing around 241 degrees.

Right now our weakest channel is Fox with a 3 on the signal strength and the other networks were 8-10. We will see how the weather effects them now.

Thanks for all the help!

KVIE-6 uses channel 9 for it's signal and KQED-9 uses channel 30 for its signal. Unless you know exactly what has scanned in. Delete 9 & 30 and re-scan 9 first before 30
Fox-40 is a co channel problem with ch 40 San Francisco
post #9235 of 10428
Quote:
Originally Posted by ellisr63 View Post

Well we got the antennae installed today... We ended up pointing toward Sacramento (around 51-54 degrees). We tried San Francisco channels but we could only get 5 channels of which 2 would be watched by us. By going toward Sacramento we got all 4 network channels and several others that we will watch. Strange thing was channel 9... It had a strong signal but the channel was blank. Channel 9 was one of the channels we would watch and it had the signal maxed when the antenna was pointing around 241 degrees.

Right now our weakest channel is Fox with a 3 on the signal strength and the other networks were 8-10. We will see how the weather effects them now.

Thanks for all the help!

When you say "Channel 9," which channel do you mean? KVIE 6 is on RF 9 and KQED 9 is on RF 30. Sounds like KQED if the signal max is at 241 degrees? Do you receive KVIE okay? A strong signal that doesn't decode means severe multipath in most cases.

It's unlikely you're getting co-channel interference from KMMC on 40 in Concord. They have only 300 watts in your direction, mountains blocking that and the F/B ratio of your antenna helping you out when pointing to Sacramento. KTXL is going to be much weaker than KCRA or KOVR because they are using a directional antenna and have only 60 KW in your direction while KCRA, KOVR, and KMAX have omni antennas with 1000KW in your direction.

With the storm we had yesterday the inversions were wiped out and signals were pretty nominal. You'll get to see what happens when the next strong high pressure comes around and the inversions set up again.

Chuck
post #9236 of 10428
When I was setting everything up and had it scanning for channels there was a perfect signal for 9.1... When we reversed the antenna to point to Walnut Grove I was still showing a strong signal for 9.6 and 9.8 (I believe) but there was no picture. I have run the setup on my other sets and the 9.6 and 9.8 do not even show up. I am thinking the Samsung didn't want to let go of the channel for some reason. So far I am very happy with the signal quality. I am going to try a HR20-700 on my main system for watching and recording HD OTA. I am getting the box with the access card so I hope that I will be able to use it by just hooking up the sat feed to the DTV dish on our roof. I am saying I hope this works because the HR10-250 I had before worked as long as it had a DTV feed from the sat.

Ron
post #9237 of 10428
Quote:
Originally Posted by ellisr63 View Post

When I was setting everything up and had it scanning for channels there was a perfect signal for 9.1... When we reversed the antenna to point to Walnut Grove I was still showing a strong signal for 9.6 and 9.8 (I believe) but there was no picture. I have run the setup on my other sets and the 9.6 and 9.8 do not even show up. I am thinking the Samsung didn't want to let go of the channel for some reason. So far I am very happy with the signal quality. I am going to try a HR20-700 on my main system for watching and recording HD OTA. I am getting the box with the access card so I hope that I will be able to use it by just hooking up the sat feed to the DTV dish on our roof. I am saying I hope this works because the HR10-250 I had before worked as long as it had a DTV feed from the sat.

Ron
Those 9.6 and 9.8 are some kind of special data channels from KQED. They're not video/audio. Most tuners don't show them, but some tuners show everything they find. My Dish receiver shows them and also gives me all of the sub-channels for mobile TV that some of the stations transmit, but I get no picture or audio on them, of course.

If the DirecTV receiver is like my Dish receiver, the OTA input only works when you are subscribed to service. Just hooking up the receiver to the dish on the roof and your TV antenna won't do any good. If you have DirecTV service, you should get just as good a signal from the DVR as you do from your TV tuner.

What antenna did you end up getting? Seems to be working quite well in your hilly terrain.

Larry
SF
post #9238 of 10428
Quote:
Originally Posted by Larry Kenney View Post

Those 9.6 and 9.8 are some kind of special data channels from KQED. They're not video/audio. Most tuners don't show them, but some tuners show everything they find. My Dish receiver shows them and also gives me all of the sub-channels for mobile TV that some of the stations transmit, but I get no picture or audio on them, of course.

If the DirecTV receiver is like my Dish receiver, the OTA input only works when you are subscribed to service. Just hooking up the receiver to the dish on the roof and your TV antenna won't do any good. If you have DirecTV service, you should get just as good a signal from the DVR as you do from your TV tuner.

What antenna did you end up getting? Seems to be working quite well in your hilly terrain.

Larry
SF
I ended up getting the HD7698P.

I hope you are wrong on the DTV tuner... I could have sworn that when I had one before it would tune and I believe record as long as you had the DTV dish tuned properly and had a valid access card even with no service. I will find out next week. I hope I didn't just buy a ashtray!

I am getting a better pic right now than I got from DTV and from cable. Def looks better without compression.
post #9239 of 10428
Well tonight I lost signal on almost all the channels... Would this preamp be a better route to go http://www.solidsignal.com/pview.asp?mc=03&p=CM-7777 instead of this one http://www.solidsignal.com/pview.asp?mc=03&p=AP8700 ? Or would I be better off to order a second antenna and stack them for more gain?
post #9240 of 10428
Quote:
Originally Posted by ellisr63 View Post

Well tonight I lost signal on almost all the channels... Would this preamp be a better route to go http://www.solidsignal.com/pview.asp?mc=03&p=CM-7777 instead of this one http://www.solidsignal.com/pview.asp?mc=03&p=AP8700 ? Or would I be better off to order a second antenna and stack them for more gain?

I doubt either of those options will make any difference. You definitely don't want a CM-7777 with 30 dB gain. That's way too much in your situation. The AP8700 is a better choice if you want to try a preamp. You cannot stack two HD7698P antennas because the stacking distance is radically different for VHF and UHF. You need separate VHF and UHF antennas and stack them like you see in my avatar.

A preamp will give you perhaps 6 dB more signal to noise and stacking antennas about 2.5 dB.

Since I don't know what your receive margin was originally and I don't know how far below the cliff the signals were last night, I can't say how much more signal you needed. This assumes that multipath did not become an issue. My experience is though that once you have a decent outdoor antenna, it's very hard to make much more progress. The antenna you have is probably giving you 80% of what's possible even if you went extremes like I have.

An AP8700 is probably the most bang for the buck. It might push 80% up to 85%.

Chuck
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