Help with KTVU (preamp overload)?

[neruo]

Here's my TV Fool report: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3de779e7fb0e3979

Here's my setup: I have an Antennas Direct V21 mounted in the attic (for a total of about 12 feet off the ground), attached to a winegard 8700 preamp. The antenna is pointed at Sutro tower (304 degrees). I have about 60 feet of new RG6 coax going to one TV. In general I get very good reception for the channels I want. Except Fox. The main transmitter on RF channel 44 is very weak, and RF channel 48 is very strong (all "signal bars" lit up, 30db+ SNR), but 48 occasionally breaks up. KCSM on RF channel 43 is weak, but usually not weak enough to break up. Other channels coming from Sutro are 4-5 "bars" with SNR of around 22db.

I'm thinking I may have overloaded the preamp.

Here are my questions:
* How do I tell if the preamp is overloaded? How do I know it's not the tuner?
* Does it mean anything if RF channels 43 and 44 are both weaker than should be expected)?
* Would a high input preamp such as Winegard HDP269 help?

Mounting the antenna on the roof is not an option (wont' pass the wife test), and I'm planning on adding a splitter and additional tuner in the future.

Thanks for the help!

[GroundUrMast]

Have you tested reception with no preamplifier parts in the system? (Remove the mast-head amplifier and the power insertion adapter completely.) The levels shown in your report are strong, arguing against the need for any amplifier at all.

If you still have trouble, the symptoms can also be indicating multipath. Multipath can be a problem in both weak and strong signal conditions. The solution may be found in repositioning the antenna (aim and or location).

FWIW, a low SNR is not proof of low signal level, but rather an indication of poor signal quality. Signal power (strength) is only one simple element in the equation...

[neruo]

Thanks.

I tried removing the amp and here are my results.

KTVU on RF channel 48 is no more stable than before. I still get high signal levels (and supposedly high SNR), but the picture still sometimes breaks up. I suppose this means I'm getting multipath interference.

I now get fewer channels from Sutro tower (for example, hardly any signal at all from KBCW, and KCSM, both of which were a bit spotty, but mostly available with the amp). I suppose this means my tuner has a poor input transformer.

For now, I think I'm going back to using the amp; since I RF channel 48 that I thought was overloaded did not improve without the amp, I take that to mean that a lower gain amp would not likely improve the situation. At least with the amp I get more (and more stable) channels.

I'll try moving the antenna eventually, but I'm not seeing an obviously better location in the attic.

[teleview]

The following is a Teleview recommendation for broadscast Tv reception.

The Tv transmissions are strong at your location.

Remove ALL parts of the amplifier , the outside part , the power inserter , the power supply.

Aim the antenna at about 335 degree magnetic compass direction.

Here is how to aim antennas , http://www.kyes.com/antenna/pointing/pointing.html.

Rescan for broadcast Tv channels.

____________

Move antenna to above the roof.

Rescan for broadcast Tv channels.

As always , trees and tree leaves do a real fine job of reducing or blocking reception and so do buildings and other obstructions.

Install the antenna at a location that has the least amount to no amount of obstructions of any type or kind in directions of reception.

[No static at all]

Experimenting with different locations in the attic may solve your spotty reception with Fox TV. If not you may need to get the antenna outside. If so, you can use an antenna with a smaller footprint, like the RCA ANT-751 (https://www.google.com/search?q=rca+ant751&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a#q=rca+ant751&hl=en&client=firefox-a&hs=0iV&rls=org.mozilla:en-US:official&prmd=imvns&source=univ&tbm=shop&tbo=u&sa=X&ei=kmBaUNOSKMbu0gGSpIDYBw&ved=0CIUBELMY&bav=on.2,or.r_gc.r_pw.r_qf.&fp=d6177351a23d2331&biw=1024&bih=605) to keep the wife happy.