PBS Reception Problem in SF Bay Area

[RogerCA]

Hi all,

Newcomer to OTA Broadcasts here. I installed an outdoor antenna on top of our condo building a couple of months ago (Winegard MS-2000). I was quite amazed at the number of channels it picked up (78, although not all of them 'usable'). I know this is an omnidirectional antenna, which may not be the best, but it was highly recommended by others living locally.

However I noticed over the past couple of weeks that reception for the local PBS station (KQED, Ch 9) has deteriorated considerably, to the point of being unusable. All other stations broadcasting from the same location (Mt. Sutro in San Francisco - Channels 2, 4, 5, 7, 11) are fine with strong signals. Interestingly enough I can pick up a much stronger signal from their translator station (KQED+ on Ch. 54; I can even get KCRB (CH 22) in Santa Rosa, almost 70 miles away). Unfortunately they don't always broadcast a 1080 HDTV signal.

I'm wondering whether this could be just an issue with multipath interference, or whether I should try to adjust the antenna (since I think omnidirectionals don't actually receive stations in a complete 360 degree pattern). Below is a link to the TV Fool signal analysis for my location:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d46ae1c983cb26a

Any help would be very much appreciated - I'm at a loss... Or maybe I need to get a different antenna?

Thanks so much!
Roger

[GroundUrMast]

You can find a small amount of directional behavior with just about all the 'omnidirectional' antenna designs. Try rotating in 10° increments...

Also, closely inspect for moisture in connectors or physical damage to the the coax, including sharp bends or crushing. These can cause problems that seem to affect only one or a few channels. If in doubt, try a new piece of coax (one of the least expensive test tools you can have). Coax-Seal or Scotch brand # 2228 Sealing tape is recommended on any connection exposed to the weather.

[teleview]

Bad connections and bad coax are the first situations to check.

Water damage of connections , water damaged coax.

The coax and connections can look good and still be bad.

As a Test.

Run a continues length of NEW coax that has the compression type connectors , not the old crip type connectors , through a open door or window , direct to one Tv.

_________

Tvfool shows the Real channels that are transmitted and received , and the , virtual numbers.

KQED Real UHF Digital channel 30 , virtual number (9.1) , PBS .

[RogerCA]

Thanks for your replies, folks.

First of all, I must apologize - the antenna I'm using is actually an MS-3000 (which is the same as the MS-2000 but with a Power Inserter).

As for the coax - that's the same as was installed by Dish for the satellite receiver. It runs from the roof of our building (above the 4th floor), into my unit on the 2nd floor. All straight runs, no kinks, etc. Only one TV connected, no splitters. I sealed all the connections when I installed the antenna.

Interestingly enough, I only get KGO (7/7.1,2,3 - Sutro Tower) and KNTV (12/11.1 - Mt. San Bruno) plus a few foreign language channels without the power inserter (total of about 35). I get a total of 70+ channels with the inserter.

Running a new coax isn't really possible, given that its such a long run down the side of the building where I don't have easy access. I spent a couple of hours tweaking the orientation to see if it would make a difference (even though it is a multidirectional antenna). Seem to have found a 'working' setup; still not perfect, but probably as good as it can be. I'm still puzzled by the signal strength difference between the Sutro stations, but I'll live with it...

Thanks for your help!

[GroundUrMast]

Interestingly enough, I only get KGO (7/7.1,2,3 - Sutro Tower) and KNTV (12/11.1 - Mt. San Bruno) plus a few foreign language channels without the power inserter (total of about 35). I get a total of 70+ channels with the inserter. That's expected when using an amplifier. Turn the power off and you can expect to get very little signal through. In some cases, strong local signal may be powerful enough to get through the shielding of the TV tuner or coax shield.

If you are interested, we can suggest other antenna options...

[RogerCA]

Thanks - I'm open to suggestions :). A more powerful directional maybe?. Was just wondering whether the signal difference could be difference in transmitter power. KQED has about 730 Kw, KTVU, KRON and KPIX all have about 1000....

Thanks - I look forward to your suggestions!
Roger