LA channels from San Diego

[scottcolson]

Hi all, I'm trying to receive Los Angeles TV stations from North San Diego county. I have an Antennas Direct DB8e antenna pointed at Mt Wilson in LA which is about 75 miles from me. I have a Channel Master Amplify preamp set to high gain installed at the antenna. I am able to pull in many UHF channels at around 60% signal strength including many with a high negative NM (-20 to -25 dB). The channels that I can pull in include 58.1, 50.1, 5.1, 40.1, and 4.1. All of these channels are in the 31 to 41 UHF channel range which is expected.

My problem is the upper VHF channels especially channel 11.1. I know the DB8e is a UHF antenna so I purchased a Stellar Labs 30-2476 Deep Fringe High VHF antenna. I disconnected the DB8e and connected the 30-2476 then pointed it at the same spot on the horizon as the DB8e. Nothing. I cannot get any signal on channel 11.1 no matter where I point the antenna. My TVFool report shows channel 11 with a -4.6 dB NM so I would think it would pick up something. What am I missing?

Thanks in advance. TVFool Report to follow: http://www.tvfool.com/?option=com_wr...e6a48429452a66

[jrgagne99]

Pulling in a signal with NM=-4.8 dB is tough. I'm amazed that you're pulling in the UHF channels you mention at -20 to -25 dB. Are you getting them reliably, or was it a sample size of n=1 (could have been favorable tropospheric effects)? In either case, these are all 2-edge signals, and folks here will no-doubt tell you you these are tricky beasts to tame. Maybe try walking the roof with your 2476 yagi to see if you can find a Ch-11 hotspot, then plug the DB8e back in and see if you still get your UHF channels there as well. Finally, use a good quality UVSJ to combine them them (i recommend the Antennas Direct one).

Interpreting NM in TVFool reports:
www.aa6g.org/DTV/Reception/tvfool_nm.html

[JoeAZ]

Welcome Scott,

It is amazing you get anything from L.A. at all.
The terrain to your north is mostly mountainous
and some of the highest peaks may be blocking
the signals for the Hi VHF stations. Walking your
roof with the antenna night just find you a "sweet"
spot for Rf 7,11 and 13. Good Luck!
This could be one of those cases where the TV
fool report is not accurate.....

[rabbit73]

Welcome, Scott

Interesting problem. You should be able to receive KTTV, but you can't.

I am able to pull in many UHF channels at around 60% signal strength including many with a high negative NM (-20 to -25 dB). The channels that I can pull in include 58.1, 50.1, 5.1, 40.1, and 4.1. All of these channels are in the 31 to 41 UHF channel range which is expected.

I don't see any callsigns or real channel numbers. I don't see any callsigns or real channel numbers. If they are listed at the bottom of your report, it is difficult to receive signals with a NM of less than -10 dB. If you are able to receive them, you have an excellent antenna system, your tvfool report is wrong, or they have been enhanced by Tropospheric Propagation.

My problem is the upper VHF channels especially channel 11.1......I disconnected the DB8e and connected the 30-2476 then pointed it at the same spot on the horizon as the DB8e. Nothing. I cannot get any signal on channel 11.1 no matter where I point the antenna.

Can you pick up KFMB and KGTV with the antenna connected directly to the tuner?

Can you pick up KFMB and KGTV with the Amplify set to low gain?

How long is the coax line from the preamp to the power inserter?

[scottcolson]

Hi and thanks for the responses.

It's funny but the most reliable channel I pick up is KLCS which has a NM of -25.4 dB. That's why I figured that KTTV at -4.6 dB would be a piece of cake.

The coax is 50 foot to the power inserter. The Amplify preamp lights up when plugged into the coax so I'm assuming power is good. Also, the 2476 has a tilt feature. The antenna is 40 ft up with no immediate obstacles. What should the tilt be?

I will try pointing the VHF antenna south when I get home both with and without the preamp and will report back the KGTV and KFMB numbers.

[scottcolson]

Ok, so I pointed the antenna South and both KFMB and KGTV come in at 85% signal strength no matter if the Amplify preamp is connected at high or low gain or if it's not connected at all. It seems that the max signal strength of my tuner is 85%. I'm gonna try another tuner.

[rabbit73]

It's funny but the most reliable channel I pick up is KLCS which has a NM of -25.4 dB.

I would have thought your most reliable channels would be from the S and SSE. Why are you messing with LA?

Ok, so I pointed the antenna South and both KFMB and KGTV come in at 85% signal strength no matter if the Amplify preamp is connected at high or low gain or if it's not connected at all.

That sounds good to me.

It seems that the max signal strength of my tuner is 85%.

That's entirely possible. The signal strength indicator is only relative, and will vary from brand to brand, and even within the same brand.

What make and model is the tuner/TV?

In a case like you have where the tuner is Maxed out, I insert a variable attenuator between the power inserter and the tuner to find out how much attenuation can be added before dropout. This is called margin to dropout, and often requires a combination of a variable attenuator and a fixed attenuator.



Here is an example of when I was comparing a Channel Master 7003 tuner with my Sony tuner:
Thread:
http://www.avsforum.com/forum/186-co...erter-box.html
post:
http://www.avsforum.com/forum/186-co...l#post48473881

[scottcolson]

Yes, right, the most reliable come from the South. I meant to say of the transmitters on Mt Wilson in LA, KLCS channel 58.1 has the strongest signal. My TVFool reports lists this channel with a NM of -25 dB. Go figure.

[rabbit73]

Oh, OK. Thanks for the clarification.

The tvfool reports are known to be inaccurate with weak 2Edge signals, but that is about the worst I have heard of.

Your reception of that channel is consistent with Tropospheric Propagation enhancement, which is more common at this time of year. You are otherwise pretty much in a dead zone for KLCS because of terrain interference:



Well, at least we now know your antenna and preamp are working OK.

[scottcolson]

Ok, I tried another tuner and I'm getting 45% signal on both KTTV 11.1 and KCOP 13.1 both high VHF channels. It seems that my Directv OTA tuner is flaky. I was hoping to get the LA stations just cause they have a lot more of them. Seems like a real crapshoot to me, I may just be SOL. Thanks for your help.

[rabbit73]

Thanks for making another test.

Tuners will vary a lot with their ability to capture weak signals.

How good is the reception quality with the other 45% tuner?

What is the other tuner?

You are just inside the KTTV FCC Minimum Field Strength Contour. The coverage is very spotty because of the rough terrain:



I think your location is just above the arrow where there is no color.

The link to the Longley-Rice coverage map for KTTV:

http://www.rabbitears.info/contour.p...=1423068&map=Y

[scottcolson]

It's an Insignia LCD TV from Best Buy, nothing special. There is quite a bit of pixelation on both channels 11 and 13. I do want to cut the cord and have been looking at the HDHomerun tuner. Have you had any experience with it?

[rabbit73]

I don't have any personal experience with the HDHR tuners, but the reports seem to indicate that they will beat your DirecTV OTA tuner but not be any better than your Insignia tuner. However, you will have a tuner for network use that has a helpful signal monitor.

I prefer to use a TV for TV reception, and not involve a computer. Computers are not user friendly for some household members.

[scottcolson]

I'll be stuck doing the debugging when the computer crashes. It's a shame that I couldn't get a better signal out of LA but at least the San Diego stations come in strong. Thanks again for all your help.

[rabbit73]

Glad that I was able to help you, Scott; have fun.

Best regards,
rabbit