A UHF and a VHF antenna don't interact
Sure they do, but it's only a problem if they are aimed in different directions, which is why we don't normally notice any problem.

That's where a "band separator" gizmo is useful. When one is used to combine a UHF and VHF antenna onto a single coax, this gizmo prevents them from interfering with each other, even when the antennas are pointed in different directions from one another.

Having separate VHF/UHF inputs on the pre-amp is no guarantee of success either. I have a thread about this topic here (http://www.digitalhome.ca/forum/showthread.php?t=96055).

Sure they do, but it's only a problem if they are aimed in different directions, which is why we don't normally notice any problem.Fair enough, what I meant is that unlike in principle, in actual practice there is no interaction worthy of concern when they are on a single spar or alignment. :) I rest my case, mlord. (I've been dying to say that in a Rumpole Of The Bailey flourish!)

Ha! :)

But the point here being, that if separate antennas (as in this thread) are combined (as in this thread), they had better be pointing in exactly the same direction.

Otherwise they will interfere when sharing a single downfeed, unless a band separator is used to combine them.

Cheers

I posted back in 2005.
http://www.digitalhome.ca/forum/showthread.php?t=24755&page=6

I was happy with my original set up because it was cheap and I was getting pretty good reception of pretty much all Buffalo channels and pretty good DXing of Rochester Which was often). However, my rotor was becoming less reliable as time went on, until finally it just wouldn't turn. This was back in the spring. As the summer went by, I didn't really care to get it fix until about a few weeks ago.

I phoned around and it was very difficult to get someone even to come and see it. The tower is 40-45ft self-supporting galvanized (about 40 years old) and I don't feel comfortable to do the servicing myself. I managed to get a contractor to come and take a look at it and he said it wasn't something he wanted to do. He said that he felt the tower was unsafe. He checked the analog signal to see how the reception was (which was strange because what would he have done after Feb 09?). He said something was impeding the signal. He looked south and in the distance I have a few office buildings. Although, it never bothered my reception before. His recommendation was to install a new UHF antenna on the roof (tripod) or chimney because I didn't need that much height anymore. But, when looking through documentation Stampeder offers here, I was under the impression that height was important:

7. What do I need to know about antennas?
"Mount antennas outdoors and as high as possible, free from obstructions"

I took the plunge and gave the go ahead to install it on the chimney. Initially, I did not expect to spent what I was quoted for a new install, but I wanted it done and over with and the weather is not the best now to do it myself. Plus, I had to pay for the service call if the work was done or not. Also, he recommended me to remove the tower, at an additional quoted cost, but I just don't think that it's life is over. It currently holds a Channel Master 3678 Ultra Hi-Crossfire TV Antenna and a stuck CM rotor (pointing away from Buffalo). The top section of the tower is somewhat rusted. I did buy galvanized paint last year to paint the tower, but never got around to it. I may still do it next summer.

He installed a new Delhi 14-83 and a new CM 9521A rotor drive. In a few hours the work was completed. I checked the reception, somewhat the same I received before with the tower. The additional channels were WNYO 49-1 (which I couldn't get last winter but I think they improved their signal regardless), OMNI 1 & 2, and Global (which switched on after I stopped viewing). I cannot get CHCH-DT. I don't know if it is broadcasting now. There are reports here that it's on again and off again. With the Delhi 14-83 I will not be able to get VHF channels in the future. I was told that an antenna could be added in the future. One channel would be lost immediately after the shut down (RTN). I asked if this was a good model and he told me that this model has a higher gain. But, I was hoping for a CM 4228, for the first VHF channel that will revert to 7. One draw back being at chimney level, I doubt I will get much DXing like I used to.

I still want to kept this tower and somehow try to get the rotor to move to Buffalo. If I can get that, I would be happy and I would have a second antenna. Plus, since it is a combo VHF/UHF I will received channel 7 in Feb. He said I didn't need a combo like this anymore. In the past when I had this problem, I used an old Archer rotor controller. Slowly jerking it back and forth, I managed to get the rotor to turn. But, the controller broke. Now, all new types are the quiet controller (remote control) units, which won't respond to quick movements back and forth. Does anyone have an old rotor controller that works and doesn't need it? Ebay has only a few and the shipping is expensive, which may be my only alternative because I can't get the rotor drive replaced.

Since the contractor came highly recommended by one DHer I put trust and faith that I got the best advise I could get from an "expert". I hope that I made the right decision. .

Hi Mark2074, I would agree with your installer that climbing a 40 year old self-supporting tower is not a good option given all the wear and tear on it over the years. Even if the metal joints are still strong, the buildup of crud on the tower and up on the antenna can make for a very unpleasant and/or unsafe experience. ;)

It seems like your roof installation went well, and I've always mentioned the Delhi 4BT-1483 as an excellent alternative to the CM4221.

My advice is to offer your tower and combo antenna to anyone willing to come and safely take it down. By safely I'm talking about experienced professionals like tree pruners who have the gear and the insurance to do it properly with no loss or damage. Would a truck with a 40' or 60' cherry picker be able to get a bucket up there to the antenna?

Hi Stampeder, the tower itself is 40 years old. But, 14 years ago an installer replace the original antennas (seperate VHF/UHF) because that time the rotor went bad. The combo is very clean and still in very good condition.

I thank you for the insight, I do value the opinions of you and the forum, but I will hold off on the removal of the tower for now. The new antenna is not a Delhi 4BT-1483. He installed a SFA-1483S "Super Flying Arrow" (sorry I didn't clarify before). I would have to have an VHF antenna installed in the near future. WNGS-DT Buffalo will revert to channel 7 in February and this is a great channel. I know that others are in the same situation, those who have a UHF antenna only will have to have another installed. Why aren't others installing a VHF now and avoid the extra cost and hassle later on? I already spend $800 on the new antenna system and having a good VHF antenna installed within a matter of months from this one, would be an additional cost I don't want to spend. If I can still utilize the combo, it will be a benefit to me and not to mention a big cost savings.

P.S. thanks for the spelling fix, I try to edit it but it didn't work the night before. ;-)

Hello,

I am getting ready to install a 4228 on a 15 foot mast on my house. My roof is galvanized metal aprox 30 by 40 and a single 30 degree stope. Will this affect my signal and is there a way to optimize the signal using the roof?

Hi genx, for very distant stations the answer is yes, there will be some influence. For almost all your expected stations you won't have any problems.

A few years ago I had a CM4228 on a pole with a very powerful Winegard AP-8275 preamp leaning on the aluminum siding of my house at ground level facing a neighbour's house that has a metal roof, and just for kicks I hooked it up to an ATSC tuner to see what I could get - to my astonishment I was picking up digital carriers (not lockable signals) from SeaTac on lots of the ATSC stations, and got a solid lock on CIVT-DT Vancouver which is located in the total opposite direction behind my house and huge trees. I posted about it back then:

http://www.digitalhome.ca/forum/showpost.php?p=207003&postcount=18

The lesson was that metal siding and roofs can and do bounce signals, but with Generation 5 and 6 chipsets todays ATSC tuners can easily reject such multipath interference. As I say, its the very distant, weak stations that might present a problem, but ya never know.

genx,
Many years back my parents had a combo antenna on a tower,... in fact the antenna and tower are still there, but now the functional equipment is a sat. dish.

When my Dad had the roof replaced they went with metal. Reception became horrible and thus the need for a sat. dish. The tower is beside the eaves, and the antenna is about 5' (guess) higher than the roof peak, if it where located next to it, and about 10' (guess) higher than the roof at the eaves.

Although stampeder indicated that a newer ATSC chipset will help with digital reception, you didn't indicate that is what you are using the antenna for (although we can make a solid guess since you are using a UHF antenna).

The point I'm trying to make is that analogue reception however, will very likely be affected.

As for using the roof to optimize the signal,... no. The antenna's reception pattern should already be optimized in the horizontal plane.

I had someone who considers me somewhat knowlegeable of TV antennas (almost all I know came from this forum :) ) ask me about an installation that I couldn't answer.

What is the effect of placing an antenna close to overhead cable tv and/or telephone wires? It's a no-brainer about locating them close to power lines - lots of information available about how deadly this can be.

But what about CATV or telephone? Is there a safety concern? I'm guessing that there might be interference from a CATV line given the frequencies involved. How much space should any CATV line be from an antenna?

Thanks for any thoughts you might have on this!

Attics take a huge toll on the signal you get. The few that I have measured so far have been in the 20 dB range of attenuation. Those attics are made of standard asphalt shingles, over roofing felt, over plywood type construction. I have not been in an attic like yours.

Its even worse than that. The last batch of standard asphalt shingles I used had steel wool like metal in them. It was very tough picking out the metal splinters in my hands, heh, not to mention what that does to reception.

But what about CATV or telephone? Is there a safety concern? I'm guessing that there might be interference from a CATV line given the frequencies involved. How much space should any CATV line be from an antenna?

Most of the time, IIRC there is only like 6 volts on the telephone line until a ring comes in. Then its like 90 volts.

If you get too close to a CATV line, the cable company may accuse you of stealing their signal.

If you get too close to a CATV line, the cable company may accuse you of stealing their signal.

Not only that, but its possible to pick up stray signals off the lines which means that you may either i) bring in CATV signals or ii) Interfere with the signals you are trying to get.

Its best that such an instance be avoided...

That's exactly my question - how far away does the antenna need to be away from the CATV wire to avoid interference? Right now, it's maybe 4 or 5 feet below it, and maybe 6 feet to the north of it facing south.

He's think of getting a taller mast but not sure if getting closer to the CATV wire will actually make the results worse. :confused:

How far is going to depend on a lot of factors in each different situation. The good news is, the interference lessens quadrupally with each foot away.

Please view the following link for details. Stampeder, please place this post in the right place, if it's not.

This is the original:

http://www.digitalhome.ca/forum/showpost.php?p=833055&postcount=653

Follow up is in installers thread:

http://www.digitalhome.ca/forum/showpost.php?p=842721&postcount=390

I will install my CM4221 in the attic (yeah I know.. it will be better outside.. :)

I never did it before, and I wanted to attach the antenna to the wood under the roof, then drill from the roof into the external wall (down-vertically) and fish the RG6 to the room below

Hints ? tips ? Things I need to watch for ?


Thanks

Chris

I've merged your post into this thread that contains a huge amount of info on attic mounts and the things you need to do. :)

V & E antenna came to finally service the rotor. But, they did not change it. ..
If you are still having issues then, or are just willing to wait until spring, then I'll volunteer to visit and help sort out your rotor woes.

EDIT: sent you a PM.

I need some recommendations for a new antenna mast. This is the second time the lower mast has wrapped around the side of my garage roof. I've been using cheap poles from my nearby Lowe's. The DBGH's wind resistance along with a few 55 mph wind gusts took care of this one in a flash (the transformer on a pole down the street also took a hit - it was quite spectacular at 4am).

I'm only looking for a four or five foot mast. I am eventually moving it to another point on my main roof to get it away from an atlas fir between me and Baltimore. I was thinking about using some electrical conduit, but that probably bends too easily.

http://www.digitalhome.ca/forum/picture.php?albumid=113&pictureid=558

Any suggestions would be appreciated. My DBGH has been taking quite a beating this winter.

Craig

Not certain if the ones at Lowes are fence poles but galvanized fence poles from Rona/home depot should work no? The corner 10' poles are the strongest. They go for around $10 each. Dont buy the horizontal poles they are the weekest. Quite the antenna you have there!