Problems with KMSP Signal Strength

[Ryan Van]

http://www.tvfool.com/?option=com_wr...b97d0200c32322

Existing Equipment: Outdoor mounted RCA Compact Yagi Antenna pointing at approximately 15 deg (20 feet off the ground), about 35 feet of Ultra Series by Mediabridge - Tri-Shielded UL CL2 In-Wall Rated RG6, Pioneer PDP-5010FD with built-in digital tuner. Connected 12/23/15.

I'm only interested in receiving the major networks.

KMSP (Fox) has very low signal strength on my TV and pixelates to the point of not being watchable. All other major networks are not pixelating at all. Any thoughts on how to improve my KMSP reception?

Thank you,
Ryan

[ADTech]

The issue is either on of an unfortunate antenna location (obstructed path, a reflection, or too close to some other object, usually metallic) or other electrical/electronic interference.

Try moving the antenna and try again. The "other interference" is far more difficult to identify and resolve.

[Ryan Van]

Originally Posted by ADTech

The issue is either on of an unfortunate antenna location (obstructed path, a reflection, or too close to some other object, usually metallic) or other electrical/electronic interference.

Try moving the antenna and try again. The "other interference" is far more difficult to identify and resolve.

Interesting... since my signal analysis stated I should be able to pick up the major networks with indoor rabbit ears I thought an outside antenna would ensure I'd get the networks.

Potential interference sources are... large diameter oak trees that I cannot get above, my antenna is about 10 feet above the power and phone lines that go from the pole to my house, and my antenna coax runs parallel and 6 inches away from the power cable (routed in conduit down the side of the house) and 6 inches away from the phone line (used for internet).

I was hoping it would be as simple as switching to a bowtie antenna, switching to a different shielded coaxial cable, or pointing my existing antenna at 34 deg (instead of 15 deg.). Would any of these items help with interference? I'd prefer to use my existing antenna unless a different antenna mounted in the same location as my current antenna would definitely help.

Another couple questions...
1) As you see from my signal analysis, many stations are in the same direction as KMSP, why is only KMSP impacted?
2) I could mount the antenna either strapped to my chimney or further away from the power lines. When does coax length become a problem? I mounted the antenna where I did because it was directly above where Comcast initially tied into the house and the location would minimize the coax run.

[ADTech]

since my signal analysis stated I should be able to pick up the major networks with indoor rabbit ears I thought an outside antenna would ensure I'd get the networks.

It *should*, however, the analysis cannot possibly anticipate every factor of your environment nor any mistakes that might be made by accident, usually due to seeking the "easy" installation spot.

why is only KMSP impacted?

Lousy luck, probably.

When does coax length become a problem?

Probably not, your signals are calculated to be "Very Strong".

Move the antenna a few feet using a temporary mount. Test. Repeat as needed until it works. Patience and persistence are virtues.

[Tower Guy]

KMSP is one of two VHF channels. I'd try an FM trap.

[Ryan Van]

Originally Posted by Tower Guy

KMSP is one of two VHF channels. I'd try an FM trap.

Thanks for the reply. How do I determine which FM frequency might be interfering with KMSP?

[ADTech]

Just trap them all out. That doesn't require any math.

It *might* be FM and a filter is easy to install. If you're not using an amp, it's much less likely but still possible that FM is interfering with that station. Given that your antenna isn't particularly sensitive to FM (it's probably down -5 to -10 dBd) and you didn't indicate any amp in use, FMI wasn't my first suspect.

There are several interference mechanisms for FM to interfere with VHF channels 7-13, the second order harmonic is the most common. To identify suspects, proceed as follow:

Identify the beginning and end frequencies of the TV channel. KMSP operates on VHF channel 9 occupying 186-192 MHz. Divide those frequencies by 2 which results in your suspect(s) lying between 93 and 96 MHz. You've got over 1.2 million watts of FM radiating from a site about 6 miles away of which several are in the suspect band. In other words, it's probably not a single station (if it's a case of FMI), it's a cumulative effect.

If you have any remaining Radio Shack stores around, call them and see if they might have a 1500024 (15-0024) FM Filter on hand. You'll have to call, do not rely on the website as many stores still have stuff leftover from pre-BK that isn't on the website.

[rabbit73]

or pointing my existing antenna at 34 deg (instead of 15 deg.).

Why is it aimed at 15 degrees? Is it because Fox comes in a little better at 15 instead of 34 degrees?

I see a lot of trees in your area. If it isn't the trees, it's fundamental overload from TV and FM signals.

Your FM signals
http://www.fmfool.com/modeling/tmp/1...2/Radar-FM.png

KMSP (Fox) has very low signal strength on my TV and pixelates to the point of not being watchable.

Fox is the weakest in that series of channels. The weakest is first to be affected from overload.

KMSP is one of two VHF channels. I'd try an FM trap.

Good idea.

The FM interference doesn't need to be a harmonic, it can be fundamental overload.

If you have any remaining Radio Shack stores around, call them and see if they might have a 1500024 (15-0024) FM Filter on hand.

The RS filter isn't suitable. You have KBEM-FM on 88.5 MHz only 0.8 miles away with a signal power of -9.9 dBm, if my estimate of your location is correct. You can do your own FM signal report here:
http://www.fmfool.com/index.php?opti...pper&Itemid=29

A suitable FM filter would be the MCM or better yet a HLSJ using the high and common ports.

http://www.mcmelectronics.com/produc...-FM-88-/33-341

Your first three TV signals have a Noise Margin over 73 dB even before adding antenna gain, which is overload territory.



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

It might be worth the trouble to insert an attenuator to make your signals a little weaker.

[Ryan Van]

I mounted my antenna a week ago and I picked approximately 15 deg. as a starting point. By the time I connected my system on 12/23 the roof was too icy to adjust the antenna.

There are many, many trees as you could see in the satellite image (your estimated location was correct, KBEM-FM is 0.8 miles away. With tree interference, is the best option to rotate/relocate the antenna until I get the best signal?

I think I'll start with an HLSJ and hope that will get me through until I can get back on the roof to rotate the antenna closer to 34 deg. Any preferred HLSJ manufacturers or locations/sites to by a HLSJ?

Thank you all for your assistance!

[rabbit73]

By the time I connected my system on 12/23 the roof was too icy to adjust the antenna.

Understood

With tree interference, is the best option to rotate/relocate the antenna until I get the best signal?

Try to relocate the antenna to avoid the trees as much as possible as ADTech said in post#4; trees block signals.
http://forum.tvfool.com/attachment.p...0&d=1448314548

Any preferred HLSJ manufacturers or locations/sites to by a HLSJ?

http://www.solidsignal.com/pview.asp?p=zhlsj
http://www.atvresearch.com/hlsjvhfba...-combiner.aspx
http://www.nsccom.com/browseproducts/HLSJ.HTML
http://www.nsccom.com/hlsj.aspx

Attenuator sources

variable
https://www.antennasdirect.com/store...ttenuator.html

fixed
http://www.3starinc.com/drop_in-line_attenuator.html
http://mjsales.net/collections/atten...ant=1083705673
Attenuation values 1, 3, 6, 8, 10, 12, 16, 20dB (FAM)
click on 1 dB for other values; the up and down arrows are faint