IN or OUT?

m-323 · 18-Apr-2011, 3:08 AM

hi folks.

I made up an antenna mast, 30ft of aluminum tube (which is mounted 5ft above my deck) right now the cable is inside the the aluminum tube.

the guy I bought the antennas from says the cable should be outside because the aluminum may cause RF signal to bounce around inside the tube causing interference.

I thought it was better inside for less wind resistance and to protect the cable.

at the top of the mast are two 8 bay channel masters pointing in different directions. right now they are one under the other but I intend to move the lower one down about 15 inches from the other (on advise from the retailer again)

so my questions are;

1) would you put the cable in the mast or outside?

2) are the antennas ok to be right under one another or would 15' between them make any difference?

I was thinking max height should be the goal?

and

3) is a smaller directional antenna better than the square 8 bay channel masters?

thanks for your help.

John Candle · 18-Apr-2011, 4:51 AM

Yes it is Ok to have the coax inside the aluminum tube , as a matter of fact it is the best place for the coax , better then taping it to the out side of the mast. What does not go inside the mast or close to any metal would be the flat twin lead antenna wire , but then the flat antenna wire should not be used anymore anyway. To provide real and actual help with your reception situation you can do what the other question askers do and -->do this --> http://forum.tvfool.com/showthread.php?t=4 , post the radar report , use the actual address for the radar report , and the height you are mounting the antenna from the ground up.

m-323 · 22-Apr-2011, 3:20 PM

ok here it is...

I was getting about 20 channels although today, even ch 9 which should be one of the strongest is breaking up! I fine tuned rotation, getting about 70% signal strength but it was still breaking up.

I have a booster attached just before the channel box inside. I guess next step it to put a booster on the antenna itself?

also the cable is inside the aluminum mast. Some told me to put it outside for less interference but I think its more protected inside.

I cant see how it would cause interference inside cause cables are always put through conduits without incident and the cable itself is already encased in rubber right so I don't see what difference that could make.

pretty clear today here in the GTA.

heres a pic of the antenna ....

the one loose wire is just there for emergency in case one of the other stays breaks.

the kat kould really kare less!

this is the base I designed that the mast sits on which allows me to rotate the mast if necessary.

I made a plate to attach the shrouds to which is supported by a sleeve under it, so the plate can rotate... well actually the mast can rotate while the plate stays in place.

heres the top.

GroundUrMast · 22-Apr-2011, 5:46 PM

Coax inside or outside the mast is insignificant. If the coax and connectors are in good condition and the connections are solid, even the most critical measurements will not show any difference between the in/out placement. The advantage with coax inside the mast is physical protection.

When you say channel 9 is breaking up, are you referring to real channel 40?

Signal levels are strong enough to potentially cause an amplifier to overload. The last thing you need is two amplifiers in the system. How does the system perform with the existing amplifier completely removed?

How are the two antennas combined? Depending on your answer, you may need to consider changes in this area. This is were I suspect your real trouble lies.

m-323 · 22-Apr-2011, 5:58 PM

ok well I have not tried it without the amp altogether.

I have turned the power off to the amp and then I get nothing but I have not yet tried to bypass the amp .... at least with this latest antenna configuration.

the two channel masters are attached by a 2:1 splitter like this:

GroundUrMast · 22-Apr-2011, 6:04 PM

Removing power from most amplifiers will result in no signal at all.

Combining antennas with a reversed splitter works for a few applications. For most, you will find that the result is far less reliable due to mutual interference between the signals from each of the antennas. You have more than likely built additional multipath effects into the signal path and reduced the effective gain of both antennas. Amplifiers are not going to correct this.

Consider running a separate down-lead for each antenna. At the TV, select the desired antenna with an A/B switch.

I have chosen a different solution. http://forum.tvfool.com/showthread.php?t=820

John Candle · 22-Apr-2011, 6:12 PM

I can see that you are on the right track in the pictures. One antenna is pointed at the american stations and the other antenna is pointed at the Canada stations. The antenna that is pointed at the Canada stations needs to be at a 90 degree angle (side ways) to the American stations. And the antenna that is pointed at the American stations needs to be as close as the antenna can be to a 90 degree angle (side ways) to the Canada stations and not lose to much signal strength from the American stations. Flat panel UHF antennas have Minimum reception at the sides of the antenna. . Yes separate the antennas by at least 15 inches , this is the length of the metal receiving elements of the UHF antennas and the separation will reduce cross talk between the antennas. Put the American antenna on top and the Canada antenna on the bottom. I also suggest a Winegard CC-7870 antenna combiner and use a Winegard AP4700 UHF preamp on the power passing side of the combiner for the American stations. Here is a place in Canada to buy Winegard , http://www.techdepotcanada.com , T . Try the American antenna with and without the preamp.

GroundUrMast · 22-Apr-2011, 6:23 PM

Per Winegard, the CC-7870 is just a splitter in reverse. (In a convenient weather resistant package. And with power blocking on one port.) http://winegard.com/kbase/kb_tip_res...hp?tip_num=291

John Candle · 22-Apr-2011, 6:45 PM

If you decide to go with the 2 separate antenna solution with 2 separate down leads then saveandreplay , http://www.saveandreplay.com has remote control A/B antenna switches. Also read and understand this about , Real Broadcast Digital Tv Channels , Virtual Broadcast Digital Tv Channels , Analog Tv Channels , http://forum.tvfool.com/showthread.php?t=695 .

John Candle · 22-Apr-2011, 6:55 PM

If I were doing it from the start I would use a Winegard HD7698P antenna with no preamp and aim the antenna for best reception of the American stations , the Canada stations will be received at a angle on the antenna because the canada stations are very strong. I would use a Distribution amplifier for the Tv's in the house.

GroundUrMast · 22-Apr-2011, 7:02 PM

How many sets will be connected?

m-323 · 22-Apr-2011, 9:52 PM

OMG! this is tons of Great Info guys thanks!

looks like either way, I will be taking it DOWN again which is not really an easy task.

gosh, Id like to be able to get away from the TWO down lines IF possible.

turning the TOP antenna to the US and the bottom one to Toronto makes sense. I was considering that but then thought, I can live without the US channels so I wanted to absolutely be able to get the few out of Toronto you know? so I put the emphasis there.

before I had the "US" antenna pointed about 130 degrees off the Toronto one, so it was aiming almost reverse to the Toronto one. this was in line with Rochester but then a friend said that Buffalo is closer so I tried to point it at Buffalo which is about 50 degrees off Toronto according to the map.

I guess the other option is to point them both in one direction, thereby getting the best signal and no cross signal with other channels, but that means rotating the mast to see US channels and how can I become a professional couch potato if I have to keep going outside to rotate the mast?

its bad enough now, sometimes I sit down and FORGET to pick up the remote BEFORE sitting down!

BTW for a picture, Im using the small Casio LED projector! its so small, it sits on top of a bookcase. You can hardly tell its there and we project the images on a wall about 18ft away. The image can be up to 100 inches across (not diagonally) but we have it at about 8ft wide and hte picture is just great! its our second projector. Using projectors in lie of TV has been life altering!

Sound is piped through the surround sound stereo so the experience is rich!

We dident even have to paint the wall! I have a small 4x4 projector screen that we used just to test to see the difference and yes, you get a bit more reflection, eg brighter picture, but 99% of the time the picture is just great. the only time as have to close one blind is if the sun is just going down and its only certain times of year.

there are no mounting brackets to hang a big heavy tv on and when its off (which is usually never) the room looks neat with no TV.

Kids play video games on it all the time. I will highly recommend it!

this was it aiming on another wall. we since changed the room around and the picture is even more vivid on the new wall cause its not as directly effected by windows.

in this pic, all the blinds are open and its the middle of the day. You can see the walls are taupe colour, not even white!

GroundUrMast · 22-Apr-2011, 10:27 PM

Another thought on combining antennas via reversed splitters: The phase relationship between both antennas must be maintained. This requires the use of identical baluns and identical type and length coax cables from the balun to the splitter.

Failure to observe this requirement will result in unpredictable results, in some cases, great signal on some channels but others nearly canceled out completely.