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Old 27-Jan-2015, 12:43 AM   #1
mjeck
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Cure for dropout it wet windy weather?

Hi - I'm 3-4 miles from local broadcast towers, and generally get great reception with the Channel Master CM3016 up in the attic. But occasional problems with pixellation/audio drop, especially WHDH (real channel 42), but to a lesser extent on all channels. When it happens it can be frequent and quite annoying. Definitely worse in wet, windy weather. I want to make it stop.
I've read here that this can be caused by multipath interference, even from trees swaying in the wind. That could definitely be an issue for me, several large conifers along or near LOS to the towers.

So my question: What is most likely to work best in this situation? I read somewhere that a highly directional antenna with a signal attenuator can work...if so, suggestions for antenna and signal attenuator?

More context and TVFool report:

http://www.tvfool.com/?option=com_wr...2c1591ca34dd7c

Would really like to keep the antenna in the attic, slate roof, but could probably reposition it so that it "looks" through wood shingle-sided gable end.

driving two TVs via single splitter.

I only care about the 6 or so major network stations that are all 3-4 miles to the west and all UHF. I realize the CM3016 is a VHF/UHF combination antenna. Disconnected the leads from the VHF portion a few days ago; seems better but too soon to tell.

I'd appreciate any advice!
Thanks!
Michael
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Old 27-Jan-2015, 2:42 AM   #2
GroundUrMast
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I see no reason to use an all channel antenna in this case... Certainly not in the attic. The few L-VHF signals shown on your TVFR are quite weak and probably would not be reliable even with the highest performance L-VHF antenna mounted outdoors clear of obstructions. In this case, the only thing the long element at the rear end of the CM-3016 offer is the ability to receive more interference in the L-VHF and FM bands.

I'd definitely recommend that you avoid the impairments caused by a tile roof which causes problems dry but get even worse when wet. I'd also look for a reasonable way to get over or around obstructing trees. When they're wet and swinging in the wind, they're really good at causing changes to the RF propagation which most tuners simply can't adjust for fast enough to maintain a lock on the signal. You're right, this a form of multipath interference.

I'd start with moving the existing antenna outside... no need to spend money on a new antenna yet. If you can not find a satisfactory location/aim point outside, then we can try several other steps. Adding a 10 dB or even 20 dB pad would be one of the steps to consider.

If I moved in next door, you'd no doubt see an Antennas Direct DB2E and an Antennacraft Y5713 (or possibly the Y10713) above my roof. The signal levels are so strong that any amplifier would be expected to cause trouble due to overloading/distortion. If there are nearby FM transmitters, an FM filter/trap would be indicated.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Old 27-Jan-2015, 12:07 PM   #3
ADTech
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Here's the only "Sure Cure" short of a very tall tower:

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Old 27-Jan-2015, 3:43 PM   #4
mjeck
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THanks very much, will try re-positioning first.
Is there a consensus on whether a bowtie design like DB2E or corner reflector design like a winegard HD-9032 is generally less susceptible to mutlipath problems?
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Old 27-Jan-2015, 4:10 PM   #5
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My intuition tells me that the 'capture area' of a 2-bay panel vs a Yagi is quite similar. My experience is that trees (particularly wet and moving trees) are a problem for either Yagi or panel designs.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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