What am I missing here?

[Lexpilot]

http://www.tvfool.com/?option=com_wr...e2cb373daafaba

My daughter is renting a house near UW Milwaukee campus and I hung a homemade coat hanger 8 bay on a 2X4 in the attic. There are miles of coax from dish and cable from previous renters that I used some of to run down, around and back up to the opposite corner of the house.
The antenna is in the west end in a window, there are houses in line with the stations that are only a couple miles out.
She gets everything fine except the NBC station WTMJ real channel 28 VIRT 4.1.
That is the station that has Sunday night football (she's a packer fan).
This station is in line with the others and only a couple miles out.
I was under the assumption that anything over 13 real is uhf.
Why doesn't this channel come in?
The others all show nearly 100% signal but have occasional drops to 50 or less. I think the short drop outs are interference.
Is there a good portable antenna we can try at the tv? I tried a $20 RCA flat one that didn't work well enough to use.
I can run new coax across the attic and down to the tv With a 50 foot run. Is there an antenna I can put up there to give better reception?
Help me keep her off cable please!
Thanks in advance,
Dan

[Jake V]

What's the design of your coat hanger antenna?

If it's working for everything else in the attic I'd first try moving it around a bit. Attics are not very antenna friendly. Sometimes even moving it a foot or up and down can make a tremendous difference. I'd also check connections and cable length.

If you're looking for a store bought antenna try the RCA-751 or Winegard Platinum 769 Series HD7694P pointed at about 325 degrees (measured with a compass).

[rabbit73]

What am I missing here?

You might be missing the possibility of overload with signals that strong.

With transmitters that close we need to see a report that is more accurate than block level.

Your report says
WARNING: Address was only resolved to block level and might not be that close to your actual location. For more accurate results, try entering a specific address or coordinates.

WITI has a Noise Margin of 80.5 dB (outside) even before adding the antenna gain.



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

Jake V is correct, try different locations for the attic antenna.

RCA ANT751 or GE Attic antenna 34792.

https://www.youtube.com/watch?v=1qYu...A&noredirect=1

The signals might not be as strong as listed on the report. When you are that close to the transmitter, the strongest part of the transmitted beam could be well above her location.

There are also some very strong local FM signals, but they usually affect VHF signals before they affect UHF signals. It might be worth the effort to try an attenuator in the coax line.

http://www.fmfool.com/modeling/tmp/1...a/Radar-FM.png

[Lexpilot]

Thanks for the replies.
Here is the exact location report:
http://www.tvfool.com/?option=com_wr...e2cb67d5b333d5

The antenna I made is this one:

http://www.popularmechanics.com/cult...al-tv-antenna/

Would fm interference cause the drop outs as well?

I take it there are no good indoor "rabbit ears" for a situation even this close to the transmitters?

Thanks again for the help,
Dan

[Lexpilot]

Rabbit, can you give me a link to an example of an anttenuator?
I have a CM 7777 at home with a switch that says FM trap that I leave in (on).
Do they accomplish the same thing?
Thanks

[rickbb]

Don't use the pre amp, you're already getting too much signal now.

As close as those stations are an 8 bay may have too much gain. A 4 bay should be plenty.

You should be able to get just about any antenna to work with those signals. If you can't then something else is going on. Could be interference from FM, or high voltage towers in the way, etc.

Look at the cables. Cable and dish installers don't need to be very particular with how they install as they are dealing with a very strong signal and aren't paid on how much cable or how many splitters they piggy back together.

All that sloppy cabling can kill an OTA signal, cause drops, etc.

I've had to re-cable 3 houses because of the messes the cable guy left behind.

PS, if you want to DIY and antenna look up Mclapp's designs. His are WAY better than the link you posted.

[rabbit73]

Thanks for the exact location report; the signals are slightly stronger.

The antenna I made is this one:

That antenna isn't an optimum design, but with signals that strong it has more than enough gain. Did you add a reflector to make it directional? A reflector can eliminate multipath reflections which can be a problem for an indoor or attic antenna.

Would fm interference cause the drop outs as well?

Yes; you can add an FM filter. Antennas Direct has an FM filter; you might need 2 in series.
https://www.antennasdirect.com/store...on_filter.html
I redid your FM report to match your new TV report; the signals are still very strong:
http://www.fmfool.com/modeling/tmp/4...e/Radar-FM.png

I have a CM 7777 at home with a switch that says FM trap that I leave in (on).

Yes, some preamps have an FM filter, but as rickbb said

Don't use the pre amp, you're already getting too much signal now.

Do they accomplish the same thing?

An FM filter makes the FM band signals weaker; an attenuator makes all signals weaker.

I take it there are no good indoor "rabbit ears" for a situation even this close to the transmitters?

Many people have had good results indoors with the Antennas Direct C2V. If you buy the BestBuy C2-V-CJM version, I think it comes with an indoor base.

https://www.antennasdirect.com/cmss_...ickStart_f.pdf

Rabbit, can you give me a link to an example of an anttenuator?

A splitter can be used as an attenuator. A 2-way splitter gives 3.5 dB attenuation; a 4-way, 7 dB. But you might need more than that. Antennas Direct makes a variable one:
https://www.antennasdirect.com/store...ttenuator.html

There are inexpensive fixed value attenuators:
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

The attenuator will make the TV and FM signals weaker.

[ADTech]

If you buy the BestBuy C2-V-CJM version, I think it comes with an indoor base.

It comes with a 20" compact J-mount for attic or outdoor use, it doesn't come with a base, though. However, it was re-done a while back so it simply can free-stand on the reflector and the bottom of the loop making an indoor stand unnecessary most of the time.

[rabbit73]

For the filter and attenuator to be fully effective, you might need to ground the coax shield with a grounding block connected to the house electrical system ground. Otherwise, the interference might get directly into the TV cabinet. It is not required by code, but might make a difference in performance.

Please let us know the results of your tests on this same thread.

Best regards,
rabbit

[Lexpilot]

Thanks for all the replies, it was worth the 5 day wait.
To be clear, the CM7777 is on my house 40 miles north of Madison not the daughters house in Milwaukee I'm working on.
The coax does go through a splitter/ grounding block. Should the FM trap go between the antenna and the splitter/ grounding block or closer to the receiver?

I've seen a piece of screen used as a reflector for the home made antennas, should it be connected to the shielding or insulated from everything.

If I give up on the coat hanger antenna which one would give best results, the C2V-CJM or the ANT751?

I'm going on Sunday to attempt the fix. I might just find that aiming it a bit differently with a reflector will help.

Thanks again guys, I post back after this weekend.
Dan

[rabbit73]

The coax does go through a splitter/ grounding block. Should the FM trap go between the antenna and the splitter/ grounding block or closer to the receiver?

It doesn't matter when you are not using a preamp. The attenuator and the FM filter can go any place convenient between the antenna and the TV.

I've seen a piece of screen used as a reflector for the home made antennas, should it be connected to the shielding or insulated from everything.

It does not need to be connected and can be mounted on wood. In the attic you could even use aluminum foil on cardboard.

If I give up on the coat hanger antenna which one would give best results, the C2V-CJM or the ANT751?

Either one is suitable for the attic, but the C2V would be safer and more attractive for downstairs.

[Lexpilot]

Thanks Rabbit, I found the Clearstream at Wmart for $100 and ended up getting a ANT751R for $46.
I'm going to try a reflector and readjusting the aim before trying the new antenna.

Not sure if you can tell by my user name or my approach to this set up, I am a cheapskate. Pilots are notorious for being cheap and suck up all the free stuff we can get!

I will report back with results,
Dan

[Lexpilot]

Turns out the landlord replaced the little windows in the attic and threw my antenna on the floor when he changed the one on the west end I had the antenna hung in.
I put on the screen reflector and put it in the rafters and this time I pointed it 320 degrees and about 5 degrees up since I'm only 2.5 miles from the towers.

Now we get all the channels in that direction at 100% solid without budging!!
When it was in the window facing 270 degrees, it was getting mid 60s with occasional pixilation.
Not sure if it was the reflector, aiming direction or the slight looking up that did the trick but she's a happy Packer fan again.
Thanks again guys for the advice and I've been reading up on this and the gray- Hoverman antennas and might start a new thread to improve my setup at home.
Here's a pic or two of the zero cost unit:

[Lexpilot]

Guess I can only put one pic in a post?

[rabbit73]

Thanks for the good news; glad she is happy.

You can have more than one attachment; just click on the Browse button again to add another one.

[ADTech]

You can have more than one attachment; just click on the Browse button again to add another one. _________________

They also have to have different file names. :thumb: If you use the same file name, you'll only get one (the last one) of them.

[rabbit73]

I have 9 attachments on one of my posts, with one of them showing in the post:
http://forum.tvfool.com/showpost.php...27&postcount=7

I edited your two photos, added them both as an attachment to this post, and made them show in this post.

I've been reading up on this and the gray- Hoverman antennas and might start a new thread to improve my setup at home.

You have made a good start with your DIY antenna. On future DIY antennas, the elements should not be directly attached to wood. They should be insulated from the wood because the ends of the elements where they are attached to the vertical feed lines are high impedance points sensitive to loss.

I don't think the original plans for your antenna give the vertical spacing for the distance between the bays. It should be about the same as the element length on each side. The M4 antenna (for mid-band) designed by mclapp has 9-1/2" elements on each side with a vertical spacing between the bays of 9".
http://m4antenna.eastmasonvilleweath...0Drawings.html

[Lexpilot]

Yes the plans for the antenna I used showed the spacing for the elements.
The vertical feed lines are .o41 stainless safety wire and are wrapped around the screws under a washer holding the elements to the wood. There should be no loss between the feed wires and elements.

I figured out the picture attachment issue, thanks for the replies.
Dan

[rickbb]

Wood can conduct electricity, but being inside and with strong signals you can get away with using it.

For any outside use you will need to use either plastic mounting or use insulating stand offs. When the wood gets wet it will ground out all the elements otherwise.

I like using Mclapp's 10 x 9 1/2 design, for me it gets the one hi-VHF station in my area without having a separate VHF antenna.

[Lexpilot]

Thanks rick, I know wet wood can conduct.
This actual piece is from an antique book shelf and is bone dry. I would bet if I checked it with my megger it would have insulating properties as good as PVC.

I'm not sure if I should start a new thread but I'm using the uhf portion on a combination unit I cut apart and it works pretty well. I'm 35 miles away and there is terrain and trees blocking the line of site to the transmission towers. It seems when it's windy, and the trees are moving I get occasional pixilation and less than optimal signal strength.
I have the antenna on a pole as high as I dare go and it is supported very well with guy wires so I know it is not moving on the wind.
My question is: Would one of these flat bay type or the Gray/Hoverman give better results?
I do have a CM7777 amp on the antenna and coax inside. It will not even display without the amp.i normally see mid 70% on the tv signal meter.
Should I start a new thread with the data report?
Thanks,
Dan