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Have you thought of just using an A/B switch for two simple exterior antennas? You can get A/B sws that have remote control. You might even be able to use diseqc switches with OTA antennas if you program a cheap experimenter's board to provide diseqc cmd sequences--you can get such boards for $2 or more if you want one with more functions. Diseqc cmds do not need much more than 8 pin microcontroller (you can find diseqc switch schematics that use just an ATMEL microcontroller on the sw side)
Before Ratshak went under they had a nice A/B switch that was remote controlled, and it was compatible with most Logitec remotes.
I also think Antennas Direct has one.
You don't need an a/b switch with a combiner folks.I'm pretty certain a remote controlled a/b switch won't be as reliable as a Channel Master combiner,& probably less money.
Also if he uses two separate TV antennas they should be isolated from each other, (one at each end of the roof) or they can affect each other if mounted on the same mast, it is very difficult to co-phase two antennas pointing in different directions, it's very tricky to setup without an RF spectrum analyzer, be-leave me I have done this for a living.(many moons ago)
You just cant connect two TV antennas together without calculating the correct co-phasing harness and spacing of the antennas and expect it to work, also most dual or quad antenna setups have all antennas pointing in the same direction.Quote:
Originally Posted by The Noof
With two TV antennas pointing in different directions they will interact, one antenna will still pick up station "A's" signal and try and add that to the signals from station "A" on the second antenna going to the TV set, the signals will be out of phase and this will cause phase cancellation, you will then be back to square one, a poor or no signal.
The problem is the interaction of the 2 bays/grids, especially on stronger stations.Both antennas will receive signal on stronger statios & the ghosting begins.lolQuote:
Originally Posted by Terryl
I use 2 4228 Channel Master 8 bays with a channel master combiner & preamp.They are on a rotor mast, mounted beside each other & the reception is outstanding.Phasing is everything
I totally agree, "Phasing is everything", two antennas of the same brand and make, the proper spacing, the proper length of coax from each to the combiner, and they both are facing the same direction.Quote:
Originally Posted by The Noof
But when you try and add two antennas together pointing in different directions the problems begin.
It can be done with proper shielding between the two antennas.
Agreed...when I suggested a second antenna, I wasn't suggesting they share the same mast:As far away as possible in fact.I never finished my conversation with the o.p because he didn't seem like that was a solution for him.Quote:
Originally Posted by Terryl
On a side note, I too have quite a few installs ( some better than others) since the popularity gain in uhf/ota free hd.I've learned much in a few short years,& been able to make many people happy.
I was thinking if one used a microcontroller for diseqc cmd then you could also have it programmed to respond to the TV remote controller as well--maybe set it up so that when you receive a given channel it sends out the correct cmd to select needed antenna--just need to add an IR sensor and they are cheap. It might be that one could use an FTA box for something like this too, maybe put the OTA antenna on the same line as a dish (OTA uses 50 MHz to about 600 MHz right now and FTA LNB uses 950 MHz to 1450 or maybe 2150--so little issue with the cable handling the signals but maybe issues with OTA antenna amp) might be issue if the FTA box does not get lock on a signal though--they tend to send out a switch reset cmd then set the port and that causes a dropout of signal. Maybe use an old FTA box that one could re-program to do what is needed or use a cheap FTA box and get creative with code.
Not really something that most in the hobby would tackle, but something that is possible. This guy likely is better off just rotating his current antenna by hand. But....
Quote:
Originally Posted by Terryl
I have one like this with a rotor and it works great. I'm also 70 miles east of TO. I get Toronto, Rochester, Buffalo and Hamilton.
In all over 40 channels.
I run 2 UHF antennas in the attic. It is a large attic so I have a 2 bay UHF and am able to get stations almost 90 miles away with that one, I have a cheap small yagi pointed 90 degrees or so away from that and it is probably 6 feet away from the 2 bay and it gets my closer UHF locals. I manually switch them as I don't have the switching setup.
If your stations are strong enough, I would just run 2 smaller UHF antennas and point them permanently. The 2 bay I have works excellent. Although I am running an amp. That is assuming what you are trying to get is UHF.
OK Kids, here is the problem with trying to run two TV antennas on one system without an A/B switch (of some kind) or total isolation between the two antennas.
ALL TV antennas have what are called "Side Lobes", (except for the spun aluminum dish) these side lobes can pick up signals or reflected signals from ether side of the antenna, they also have a back lobe, this would pick up signals from the back of the antenna, these lobes are not as strong as the main beam or front lobe of the antenna in question, and all antennas have different lobe patterns, and all channel elements create a different lobe pattern.
Here is an example for one single channel.
Attachment 26755
And it gets real complicated with a multi channel antenna like a TV antenna.
So the problem with using two TV antennas to try and point them in two different directions at once and combine them into one system is very difficult, it can be done, it all depends on the location of the transmitters, and the location of the antennas.
Some places the terrain will provide enough isolation or not have a problem with the main signals from one direction reflecting into the side lobes of the other antenna, some places you can isolate the antennas so they can not see the stations from the other direction, or you can use shielding to isolate the side lobes from receiving the apposing stations or the reflections from the other stations from the other direction(s).
If antenna "B" can see any type of reflected signals from the location antenna "A" is pointing to (and the other way around) and your combining them somehow without using an isolation switch,(channel combiner, two way splitter, A-B input on an amp) there will be phase cancellation of some signals, what ones and how bad depends on the channels transmitter strength and the terrain.
So it is best to go get a remote controlled A/B switch and use that way to combine the two, there will be less hair loss over time.
And lastly it's all Location location location.......Some places it could work, other locations it's major hair loss.
I am using Lava HD-2605 Ultra Remote Controlled HDTV Antenna with G3 Control Box with Ultra 4 Way Splitter HDTV Certified for all HDTV Antennas for 4 TV's for the last 3 years. It is working great and I am getting about 32 TD channels.
Like I say it's all in the location.
I'm using a 40 year old Channel Master deep fringe VHF (lo and high), FM and UHF with pre-amp, on a tower with an old HyGain rotor, at 125 feet AGL, fed into an old RCA 8 way amplified splitter driving 5 HDTV sets and 3 AV tuners.
I get about 15 channels to the North west (Sacramento) and about another 15 to the South East using the rotor when I want to look in that direction, (Fresno) but most are first and second edge, (I live in the mountains) but watchable 90% of the time.
I have no problems with the FM stations I need to listen to.
Now that also brings up another problem and that's a close in FM station blanking out the pre-amp (if used) some FM stations can cause signal problems, this is why the make some amps with an FM trap, this cuts down on any possible pre-amp overload for a close in FM station. (or stations)
And again it's all in the location.
ATSC was supposed to be designed to allow for "smart antennas". That is an antenna that was built to allow for electrically direction switchable operation. They turned out to be largely vapor ware, though some of the early convertor boxes were set up output the signals required (I know RCA put out a model). The only antenna that seemed to exist to use the signals was something that was only for local, strong signals and not deep in fringe (though one could use the signals to do something interesting if you have something that outputs them).