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Discussion Starter · #1 ·
Since the trees have come out my reception has gotten much worse. Channel 9.1(34) is below 20 and unwatchable, 26.1&2(27) is very erratic and 4.1(48) has drop outs when the wind blows. Since my antenna is securely fastened to my chimney and doesn't move (it a CM4221 so its not affected by the wind) I suspect it is leaf movement or blockage that is my main problem. Anybody have any experience or opinions on this?



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Dave B.

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I have a CM 4251 Seven foot parascope that is currently considered the highest UHF gain (directional) antenna. From Ravensworth Farm, I can receive all DC stations and all of the Baltimore stations (with a few pixels on ocassion) with leafs on the trees. If you are having a signal strenght problem, I would recommend that you go to the antenna with the highest gain. The antenna is big, but not that offensive. Please let me know if you would like to check it out. Tom [email protected]
 

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Discussion Starter · #3 ·
Tom,


I was getting 27 and 48 at a 99 to 100 signal level up to about 2 weeks ago. 34 was at 80 to 85. Nothing changed but the leaves. I am thinking about relocating the 4221 to the other end of my roof. This will require a tripod mount, so I'll probably do it this weekend.


I have seen pictures of the 4251 and it does look impressive. Looks like a big mesh dish. If relocating my 4221 doesn't work, I will probably give it a try.


Do you know what the reception area (angle) is for it. It is much more directional then my 4221, so I'm concerned about getting both DC and Baltimore from my location.


Thanks for the input.


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Dave B.

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[This message has been edited by dmbatch (edited 06-06-2001).]
 

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Dave,


If you don't have rotor, you should get one. Even stations transmitting from the same mountain will require a few degrees change for best reception. Also, the 4221 is not very directional and does not reject multipath very well, you should try a 4248 and mount it on a rotor.


See this thread for some antenna comparisions:
http://www.avsforum.com/ubb/Forum11/HTML/013407-2.html


Glenn
 

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Discussion Starter · #6 ·
Thanks Tom,


It looks like the 13 to 16 degree range of the 4251 would work for me without a rotor. The only exception might be WETA(27) but it's close enough to my house that it might not matter.



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Dave B.

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Dave, I don't use a rotor on the CM4251 Parascope and get all DC & Baltimore stations, including 27. I also have a Winegard 9095 UHF with rotor. I use UHF amps (7775 & 4700) on both antennas. I think it would be much easier to use a rotor with a CM4248 than it would be with a CM4251. I also had to get an extra chimney strapping kit, using four bands to hold the CM4251 in high winds. Tom
 

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Discussion Starter · #8 ·
Tom,


I have the 4700 on my 4221 now and it seems to do a good job of bringing in the distant stations without over saturation on the closer ones. I hope I can just find a spot on my roof that will allow my 4221 to work like it did before. If not, I'll be looking into something with more gain. The advantage to the 4251 is that I think you could tilt it like a SAT dish. That would make it easier to miss the trees.


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Dave B.

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Quote:
Originally posted by dmbatch:
Since the trees have come out my reception has gotten much worse. .... I suspect it is leaf movement or blockage that is my main problem. Anybody have any experience or opinions on this?
Yes, Since the leaves came out, I have lost WTTG (Fox 36). I'm hoping that these problems will be mostly cured when the various DTV stations go to full power. Otherwise, the only alternative is to erect better antenna setups.


--Gerald C




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STOP DVI/HDCP!
 

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I am using a CM 4248 and CM 7775 preamp. The antenna is in the garage attic, and I was also having problems with the signal once the leaves came out. There is one very tall oak tree in the way. I was luckily able to move the antenna to the other end of the attic so it no longer pointed into the tree. The reception improved a lot...its much more stable.


One interesting thing to note, since I got the CM preamp the signal strength of WUSA, WTTG, and WJLA(yuck!) didn't budge at all. They are all in the upper 70s to 80s. But, it improved WRC from a signal in the 40's to the 70's. I was really hoping it would improve PBS, but unfortunately the preamp didn't help PBS at all. The most I can get out of that channel is a signal of 10 - 20 which is totally unwatchable. I guess they are just broadcasting on too low power for me to pick up.


Ben
 

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Discussion Starter · #11 ·
I raised my 4221 up about a foot in it's current location and got some improvement. 27 is back to upper 90s, 48 is back to 99-100 and steady, but 34 is now gone completely. But.....38 in is the low 80s and steady, so I can get my CBS from Baltimore.


I am still planning to move the antenna to the other end of the roof tomorrow.


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Dave B.

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Dave,


Your highest gain is in the center of beam spread. I even rotate my antenna for stations broadcast from the same mountain 130 miles away, to get the best results. You will never get good results if you are trying to pickup different locations at the extreme of the acceptance angle.


What is preventing you from tilting the 4221? It would take a special mounting structure to tilt the 4251.


If you check the link I posted, you will see the 4251 does not perform well in multipath, and neither does the 4221.


Glenn
 

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Dave,

Before moving your CM 4221. Try tilting the bowie antenna first. I also had drop-outs before. But I went ahead and bought a 5ft mast from Home Depot and made a "T". And tilted the bowie at about 45 degrees and cured all problems.

Go to the AVS Forum and look for "How to tilt a uhf ant."

I found out that CM 4221 works best when tilted rather than

on an upstraight mount.


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PeterDz
 

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Dave,

I cut the 5 foot mast in 2 pieces 1 was about 3 ft for the back of the wire mesh. And about 2ft for the mount to be placed on the rotor. I drilled a whole side by side on the mast and bolted it together. So it looks like this " /l" just picture the 1 under the /. I tilted the antenna at about 45 degrees. With this set up you can still move the ant face to which angle is best for you. I made the bolts tight but can still be tilted to whichever angle but doesnot move, when left by itself. If you see where the wire mesh is attached to the bowie mast, it's bronze or gold in color. That's where I intalled the u-bolts to attach the 3 ft. mast at the back of the wire mesh.


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PeterDz
 

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Dave,

Give me your email add so I can email you the picture of what my antenna looks like. I just have to go up there and take a digital photo.


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PeterDz
 

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Discussion Starter · #16 ·
My address is


[email protected]


You can also email to any poster on this forum by clicking on the little mail icon at the top of each post. There is also a way to insert an image when you are posting on this forum by clicking on the insert image icon that is to the right of the Bold, italic and Underline icons.


Thanks for the information. I moved my antenna yesterday and am getting all of the DC channels very strong. I am not getting the Baltimore channels at all though. I used a tripod mount that allowed me to tilt the mast about 4-5 degrees, but I don't think that's enough.


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Dave B.

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Dave,

I tried placing picture here but file was to big. So I just emailed it to you.

Thanks.




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PeterDz
 

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Discussion Starter · #18 ·
Peter,


How much of an angle are we talking about?


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Dave B.

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Discussion Starter · #19 ·
Thanks Peter,


I think I will try tilting mine at the 45 angle and see what happens.




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Dave B.

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OK I will throw a curveball at you guys. I live in Columbia MD. I am surrounded by trees. As a matter of fact my CM 3021 (almost identical to 4221) is on an 8 ft mast on top of my home. It has a large oak that covers most of the antenna. It overhangs the antenna and covers about a 200 degree viewing area. Anyways when the leaves came in my reception.....IMPROVED. I mean significantly. Before the leaves came out I could at least look out from my antenna and ee through the trees branches. But now I have no hope of that with the leaves. Is it possible that the stations have increased their signal strengths and or "aimed" their signal a little more northward. I am dumbfounded by this. I thought that I would be in big trouble when the leaves came out. Every single channel either became stronger or stayed the same. Ch. 38 (CBS/Balt) and Ch. 48 (NBC/DC) stayed the same and everything else increased, with the most noticeable being WETA. I used to get 22 or so (in other words nothing) on WETA and now I get a solid 58 with little to no dropouts.


Go figure

Dino
 
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