My parents recently installed a new antenna and amp at their location and are now receiving HD signals from 4 different cities with their rotor(see tv fool below) They are receiving distant signals but their signal strength meter is between 80-95% on almost all channels. The problem is that their signals will drop to zero randomly no matter what channel they are watching. They are using what I believe is the Winegard HD8200U http://www.solidsignal.com/prod_display.asp?prod=HD8200U and the winegard 8275 Amp http://www.solidsignal.com/prod_display.asp?PROD=SAP8275
The antenna is mounted on a mast about 15ft above the roof line of their Morton Building, similar to this http://www.mortonbuildings.com/Garage-Suburban-Storage/Country-Craft.aspx, can this steel building be causing severe multipath?
The antenna run is about 150ft of RG6QD and is not split between the antenna and tv.

The stations to the north the antenna is "looking" through tall pines and the stations to the South and East are clear of any obstructions.

If the building may not be to blame, is the antenna and amp good enough to hold the signal or are they the cuplrits?

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d23c5c8062e0a30

Given that almost all stations are pretty weak and you have long coax run may want to think about using a preamp at the antenna, CM 7777 is a nice VHF/UHF preamp.

You are losing about 8 dB due to coax and the preamp will have a much lower noise figure then typical TV tuner.

Thanks for the feedback, sorry I forgot to include the preamp model, and i had the wrong model number

Hmmm, interesting. I have three nearby neighbors with metal roofs and roof mounted antennas (~5 to 8 feet above the ridgeline). They are pleased with their tv reception and did not mention any issues with varying reception over time. Based on their experience, I likely will install a metal roof on my home within a few years. Our signal strengths are significantly stronger than yours (NM's range from 40 to 56 dB).

They are receiving distant signals but their signal strength meter is between 80-95% on almost all channels. The problem is that their signals will drop to zero randomly no matter what channel they are watching.

If the building may not be to blame, is the antenna and amp good enough to hold the signal or are they the cuplrits?

I think that they are doing as well as they can from that location. The antenna and preamp are optimum for that location.

As for what's causing the dropouts, one option is simply the signal fading. There's not much that can be done about that. I tried a 50' tower at their location and it didn't help much. A 100' tower did help and made a bigger difference with the Albany stations than Utica or Binghamton. A 150' tower wasn't much better than a 100 footer.

Another possibility is electrical interference from something that cycles on and off. Listen to an AM radio on 540 KHZ (Daytime only) and listen for a loud tick when the signal drops out. If your parents can hear a tick that coincides with the DTV dropout, that confirms electrical interference.

If interference is confirmed the next step is to figure out what's cycling on and off at that time. Furnace? Exhaust fan? Well pump? Refrigerator? Hot water heater? Hot Tub? Air conditioner?

Are you absolutely sure it's all channels? There are a lot of VHF chs in the tvfool results. They are usually more prone to interference than UHF chs., especially for fringe reception. Interference from electrical devices, lightning, other VHF channels and FM radio stations are common.

I know it definitely happens on 6 and 29 the main channels they watch

I wouldn't hold out much hope for an interference-free channel 6 at that distance. Too many things in the air to disrupt that channel. The pine trees may be affecting reception of 29.

thanks for all of your assistance, if anyone else has any thoughts please weigh in, thanks again