San Francisco, CA - OTA - Page 228

This weekend started with a 4220 (2Bay version of 4228). All stations came in better unamp'd than my previous amp'd antenna. I did practically no aiming whatsoever, slung the thing on my existing dish under-eave mount (read: jammed into the gutter/dish), and it works fine. Worst channel is 48 (don't really speak Spanish that well) at a 73 reading (using Dish receiver -- typically anything under 66ish is a lost cause). 1, 11, 28, 54, 14, 36 climb from there, and everything else is mid 80s to 100 for 26. Channel 20 (which used to be a lost cause) is reading 98, and 44 (which was spotty) is now 90. Ch 1 is actualy new, and I'm now receiving ch9 (I thought kqed on ch54 was all there was!).

All readings taken at 5AM -- likely to be lower during the day.

For *me*, this is fabulous. YMMV, and thanks again,

-Dave

[quote=gosmond;19120786]As I say in my earlier post -- when I look on channels 26.1-26.4 and 27.1-27.4, the AGC / SNR / Errors / Signal strength read-outs on my TV show nothing at all -- no sign of life -- no matter what the antenna position.

Re-boot the tv. And make sure you are in antenna mode ... Not cable mode.
Scanning errors... Do a "double-scan". To wipe out previous attempts.
There is nothing on 26. --- Set your tv to 27 see the owners manuel.
Use another tv... to verify this is a signal issue.
Something will work.

[quote=888CALLFCC;19122825]
I appreciate your remarks. I am of course in antenna mode, not cable mode -- as I said, all of my other OTA stations come in fine.

Here's a question:
When I do the "channel scan" function on the TV, where it takes 5 to 15 minutes to search for channels, if it does NOT find a channel during that scan (say, KTSF,) does it then completely lock out that channel from any future reception? (I hope not.) I am manually punching in 27 (and 27.1, .2, etc.) on my remote, which yields "no signal" on the TV, and then I'm using the Diagnostics feature to try to antenna-hunt for some sign of signal.

If it's the case that the channel MUST be located first by the TV's auto-scan feature in order to even be considered for any future reception attempt (which would be utterly assinine programming, but certainly possible), then I need to start from scratch.

Your suggestion to use another TV as a test / verifier is a good one; I'll look into that.

Sony TV, you say? Try tuning it to 27-3 and see if anything happens.

- Trip

Thanks, already tried 27.1 through 27.4 with many different antenna position & pitch/yaw/roll combinations.

TV is a Sony KDL-32L4000 television (about 2 yrs old.) and a $12 Radio Shack model 15-1874 indoor UHF/VHF antenna.

I don't have hands-on experience with Sony TVs, but I know they can be finicky. In your case, I was thinking the issue might be with the tuner looking for it on 27-3 rather than 27-1 (there's a technical reason for it which I will skip over to avoid confusion). A number of Sony TVs handle subchannels that way and will not manually tune 27-1 if a signal is configured the way KTSF is, only 27-3. If you're signal hunting, only do it on 27-3.

I'm sorry that I have no more ideas for you. That's just the one that jumped out at me.

- Trip

That's too bad that they've taken a very useful feature and made it useless. The TV is telling you that there is no signal but we know that's impossible. Unfortunately you are left with no tools to troubleshoot the problem.

Chuck

I suppose all these Sonys are different. With mine if I tuned to 27.1 and the program was on 27.3, the Diagnostic screen would show all the information for the signal but the TV would say "No Signal" indicating you were tuned to the wrong sub channel.

Chuck

With all the information you posted here. We're down to two questions.
Is it the Sony tv causing the problem ? .... Or is it a reception problem ?

I am not familiar with that tv model, but on some of my sets here,
you must do a scan-in before the tv knows what's out there.
If I just plug it in .... And turn it on ... It won't work.

If you can hook your antenna to another tv. We'll know if it's the tv.

The tv transmitter(s) are located together, so they all come in as a group.
If your 2 miles from the tower, with blazing wattage overhead.
the meter should not read zero signal.

Gosmond,
Yes, on some tv's .... future stations are locked-out.
If the first scan didn't recognize a station. It's locked out permanently.

Scanning on a regular basis, ... adds new stations that come on the air.

How is your reception of the other UHF channels from Mt San Bruno?

I agree with trying the classic bowtie. KNTV will likely come back, and it will allow additional placement options. You need to do better than a 5-foot cable though. Location is a paramount concern. The best location for stations from Sutro may be terrible for those on San Bruno. Multipath is a bear.

I have a Sony Bravia XBR5 from late 2007. Unless a channel is recognized during a scan, the channel does not exist. New channels do not show up until I re-scan. If it doesn't pick up a channel when scanning, due to low signal levels for example, that channel will not be in the channel list. It could be putting in a signal of 33 dB SNR, but the tuner won't recognize it until I re-scan and get it into the list.

So... do a re-scan before you go any further. You could spend hours trying to find KTSF, but unless it's in your channel list made with a scan, you won't find it.

There are four transmitters on Mt. San Bruno: KNTV 11, KTSF 26, KFTL 28 and KKPX 65. Do you get 11, 28 and 65? That would indicate whether or not you're receiving signals from Mt. San Bruno.

As for the channel numbers, there is the channel that the station transmits on and also the "virtual channel" that the station sends out that's displayed on your TV set. The "virtual channel" is the station's old analog channel number.

In some cases, like KGO and KICU, the transmitter and virtual channels are the same. KGO transmits on channel 7 and channel 7 is their virtual channel. KICU transmits on channel 36 and channel 36 is their virtual channel. In most cases, though, the transmitter and virtual channels are different. KTVU is virtual channel 2, but they transmit on channel 44. KRON is virtual channel 4 but they transmit on channel 38. KTSF is virtual channel 26, but they transmit on channel 27. Take a look at my DTV channel lists linked below to see what the transmitter channels are for each channel.

Good luck with your reception efforts, Gosmond!

Larry
SF

I suggest you get an FM Trap. A highly variable signal quality reading, especially in VHF High channels is a good indication of FM interference. FM Traps are cheap, but I have not been able to find them locally.

Buy two or three of them, just in case.

The Pico-Macom HLSJ, with the "L" port capped with a 75 ohm terminator, makes an excellent 25 dB attenuator for FM band. It's cheap, only about $2 online. The Holland HLSJ is a decent second choice.

I have a Sony XBR6 and a Sony L5000. Both have a full channel scan and add scan feature. The full scan will wipe out all the TV's channels and rebuild the real-to-virtual mapping on whatever it scans. If it isn't scanned the channels cannot be received. This may be due to any number of reasons. The add scan feature allows you to re-scan without wiping out the existing channel mapping. This is handy in my case since I have two antennas - one for San Francisco and one for Sacramento. So I can add to whatever antenna 1 got with whatever antenna 2 got and rescan as new channels are added. Unfortunately the TVs have no channel delete feature so cruft can accumulate if stations move around or cease to exist.

By the way, all this discussion about receiving KTSF 27.x is a bit confusing since KTSF is RF 27 and its virtuals are 26.x. So one should be tuning in 26.x on the TVs to receive KTSF's stuff (personally I think the 26.x's are useless and hide them from my channel selections )

I live in Foster City (next to San Mateo). I recently bought Antenna Direct Clearstream2 antenna from Costco. I am looking to get the following channels: 1.x, 2, 5, 7, 9.x, 11, and 54.x

I tried multiple positions for the antenna but I have never been able to get Channel 7 (ABC). I got 1.x when I lay the antenna on the ground facing up but the signal strength is pretty low.

I then positioned the antenna on the chimney (at about 15-20 feet above ground) in the direction of north (so around 10 degrees) as the back of chimney is in the north direction. With this setup:

1) I still don't get Channel 7 (ABC). Why is that?

2) I don't get any of the 1.x channels. I see, from TVFool, that 1.x is in 99 degree direction. Is that the reason, I don't get 1.x? Does it mean that if I have to point my antenna in direction of 99 degrees? How is that I was getting this channel when I lay the antenna on the ground facing up?

3) 5 (CBS) seems to be weak. All other channels (that I am interested in except above 2) seem to be good. Any particular reason why this is the case?

Attached is TVFools Analysis.

Thanks for all the help!!!

1- Channel 7 is transmitting on the VHF band and the Clearstream2 is just a UHF antenna. It's not large enough to pick up the VHF signals unless they're very strong. They have the Clearstream5 for VHF. If you're getting channel 11, also on VHF, then that signal is strong enough for the UHF antenna to work. (See my DTV list, linked below, for the transmit channel of each station. Most are NOT transmitting on the channel they ID as, which is their old analog assignment.)

2- Channel 1 is transmitting from the same location as channels 14 and 48, Mt. Allison in the hills above Fremont. However, it's a low power station, so would not be as strong as the others. You were probably getting a reflection when you got it with your antenna pointed face up. The direction of the antenna is critical for weaker signals.

3- Channel 5 seems week? Same thing... antenna direction... channel 5 transmits from Sutro Tower in San Francisco, so your antenna should be pointed in that direction to get the best signal.

Good luck!

Larry
SF

Thanks for your response, Larry.

Regarding #1, Channel 11 is very strong. Is Channel 7 so weak compared to 11?

Regarding #2, given that Mt. Allison is pretty much in opposite direction to Mt. Sutro, what are my options? Do I need to have 2 antennas? It seems like a common issue with all OTA folks.

Thanks!

I have a 32" Vizio 720p set. I can receive all digital channels using roof top antenna. But I cannot get it to see digital channel 1-1. I tried rescanning, manually entering Ch 42-1, but no dice.

Using the same antenna feed, I can watch channel 1 on an HTPC.

Any tips with getting Ch 1 on Vizio?

Return It ... Return It ... Save your money.
Costco is selling this item on "Price Point" .... Not Performance.
What is the profit markup of this item ?

I saw a pallet of this junk also at the Hayward store.

Look online for these proven antenna manufacturers.

Antennacraft, Channel Master, Winegard,

Which model from Channel Master/Winegard do you recommend for my situation?

Thanks.

If costco sold the CM4228 .... Everyone would be happy.

Say no ... to junk antenna models !

For Foster City, Channel Master 4228 aka 4228HD, etc

Can the 4228HD receive signals from both Mt allison and Mt. sutro?

Hi,

Assuming no rotor!!

In Foster City, probably not.

In Sunnyvale, Yes. (Actual installation)

The CM4228HD has small lobes close to 90 degrees from it's main axis (A little forward of where the screen is pointing.)

I tried to find the polar plot showing this but the search into the "HDTV-in-SFbay@yahoogroups.com" failed to find my request for the plot which was met with a plot for a different antenna.

SHF

Looking at your TVFool I think you got the 1.x's because you probably just happened to get a "good" angle on the antenna (more about that below). And I assume that the Clearstream2 is not capable of receiving the vhf hi RF7.


See what I said above.


Again what I said above. RF42 (1.x) is practically on the back side of the antenna -- you just happened to be lucky when it was laying on the ground.

Basically to get those channels from your location (according to your TVFool) you will either need (a) a rotor or (b) two antennas (through an A/B switch), or (c) possibly (just possibly) and antenna without a reflector that might be able to receive signals from it's back side..

If 1.x is all you want to get there, trust me, IMO it's not worth the expense or effort.


Try turning the antenna a little more to the west and see if it improves.

The two style(s) of proven antenna models are the
1. Yagi Antenna Models
2. Bow tie Antenna Models

The "yagi" models are highly directional and need to be aimed dead-on.
The "bow tie" models offer high gains and "flexible aiming".

With "Flexible aiming"
It "may" be possible to get both locations at the same time.
No guarantees -- at your specific location.

I built a copy-cat of that model (Only 4 bays) without the rear mesh.
Installed @ Norfolk St in San Mateo on a outdoor fence.
It picked up both locations, plus Rohnert Park KRCB
So, .. that result contributed to my recommendation.

Tell us how ... it works for you !

The C2's VHF reception depends on the coaxial cable - just like your bedside clock radio uses the power cord for its FM antenna. You can usually play with the coax and make it work by forming a loop of coax off the side, but its usually easier to just buy an antenna that has an active VHF element.

I would expect the C2, if pointed at Fremont's towers, to get the Sutro/Bruno UHF stations off the back. It is actually a very well designed and efficient UHF antenna and is my favorite for close-in (within 30-40 miles) UHF work. It's also, in my opinion, the best indoor UHF antenna on the market. Loops and loops-in-front of reflectors have been a proven design for decades; to say that only Yagis and bow-ties are "proven" ignores this history. Loop antennas are similar to bow-ties in aiming characteristics since its just a circular "dipole" instead of a fan-shaped dipole.

Your inability to receive channel 7 is most likely due to FM interference would likely be present regardless of your antenna selection. Both KGO and KNTV share the market with 100 kW (or so) FM stations that are on frequencies that allow for significant 2nd order harmonics right into the channels for 7 and 12 along with the high probability of IMD from multiple PM stations at power levels several times greater than the DTV signal. Many digital tuners simply don't have any FM filtering so this problem is actually quite common but often unrecognized. In your specific case, I see both a high probability of IM2 interference from the combination of KCSM on 91.1 (11 kW from the home of the San Mateo Bulldogs) and KQED on 88.5 (110 kW from Bruno) and 2nd order harmonics directly from KQED being the primary suspects. The good news is that FMI is completely fixable with enough FM attenuation through the use of FM traps/filters or high-pass filters that attenuate the power of the FM signal. My recommendation would be to insert either two Pico-Macom HLSJ devices in series (cap the unused LO port with a terminator!) or two FMFLT filters from Antennas Direct into the line and your channel 7 and 11 problems will go away, even with a C2 antenna. I would prefer the P-M HLSJ for this application as it attenuates the lower FM frequencies by an additional 4-5 dB over the similar Holland product giving a bit more "bang" for your two bucks.

For more background on FMI, see the articles by Charles Rhodes published at www.tvtechnology.com

I'm not saying this can't happen under any circumstances, but recently there's a lot of blame being placed on this as causing non-reception of channel 7. I'd need some proof in the form of actual measurements at people's homes before I'll buy into it.

I had OTA setups in the analog days in Fremont and Sunnyvale and helped other people with their antennas and I don't ever remember seeing any interference to channel 7, 9, or 11. In Sunnyvale I could get 10 and 13 and never saw any interference to those either and they were weak compared to SF stations. 8 was good in Fremont too.

2nd harmonic interference to an analog station would be very obvious and appear as some form of cross hatching in the picture. I never saw a single case of it and analog signals are very sensitive to this sort of problem. The interfering signal needs to be in the range of 50 dB weaker than the main signal for it not to be visible.

DTV is much more tolerant of an interfering analog signal than analog TV was. I've seen analog video carriers up to 10 dB stronger than the DTV signal on my spectrum analyzer and the DTV station was still receivable.

If KQED FM was such a big problem then essentially no one who received a strong signal from KQED would be able to receive KGO, yet there are no such widespread reports. Almost all the reports of problems with KGO are coming from people who don't have LOS to Sutro and/or are using indoor antennas or UHF antennas not designed for channel 7.

The guy in Foster City is not LOS to Sutro according to his TVFool chart and is using a UHF antenna. It's not a surprise he's having a problem with KGO. A UHF antenna is likely to be even worse at receiving KQED-FM as it is at receiving KGO-DT.

A high VHF antenna has gain on channel 7 and quite a bit of rejection at 88.5 MHz, so that alone is likely to solve the problem if indeed it is a 2nd harmonic issue.

The answer is very simple: Install an outdoor VHF antenna. And if he wants to receive Fremont, he'll need a rotor.

Chuck

I live in Alum Rock, and saw a definite improvement in my reception after adding an FM Trap to my system.
On the spectrum analyzer I could see no real difference with or without the trap. That just means that the FM signal was not overloading my distribution amplifier. In order for FM to interfere with TV signals, it must overdrive some circuit. The clipping is what causes the narrow band FM signal to spread out to its harmonics. In my case I believe that the tuners were being over driven.

The problems I was having were intermittent. But that is expected when the signal strength is affected by the weather. When the FM signal is strongest, it could over drive the tuner and cause interference.

Since I have added the FM trap, I have not had dropouts on channel 7, 8, 12 or 13. Before adding the FM Trap, channel 7s signal quality was continuously varying, since adding the trap it is stable.

The FM Traps I bought cost about $3 each. At such a low cost, it does not hurt to try one.