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Discussion Starter · #1 ·
I assume these are UHF antennas? One foot is a little too close. You want to keep them more than one wavelength apart, at the lowest frequency of interest. In the installation instructions for the 4248, Channel Master recommends keeping it at least 30 inches away from any other antennas, which is about right for channel 14. This is the vertical spacing between booms (i.e., between the mounting positions on the mast).


Running two cables would be the best.


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I fully understand that you do not want a rotor driven antenna....I am just curious to why not? If you would not mind...could you explain why?


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IS THAT A REMOTE CONTROL IN YOUR POCKET OR ARE YOU JUST HAPPY TO SEE HDTV?
 

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Thanks everybody, and Ken for the link. I think the advice I've gotten so far is to keep them at least one minimum (UHV-14) wavelength apart. But from the link above it looks like that is for sharing the signal on one F-connector. It's unclear if I still need to worry about that if I run 2 separate cables and have the software choose which antenna is being used for each channel. But I guess it can't hurt.


Again, though, I was just doing this to point in two different fixed directions. The antennas would not be parallel.


I guess the reason I dislike rotors is because they are not automatic and you have to wait for them. It seems clunky and makes it harder to channel surf. As a computer software guy I tend to avoid and distrust all moving parts, whenever possible.


My family had a rotor all the time when I was a kid. Maybe it just seems like old tech.


- Tom





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Tom,


Don't underestimate the power of an IR controlled rotor. CM has one that is really smooth. You get a little box with a 3 digit LCD display that indicates the bearing location in degrees, and you can program up to 69 different presets for the channels & locations you want.


Cost is about $70-90, and you can upgrade to a better HD rotor, if desired.


If you use a remote that does macros, you can program channel changes and antenna direction all in one neat little string.
http://www.starkelectronic.com/cmmatv.htm#rotor


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Hi -


I've been using a WinTV-HD card for OTA reception here in Southfield MI.


According to www.antennaweb.org, all my HD stations are more or less in one of two directions, either SE or SW from me. Now back last fall when I got set this up I could find a single compromise direction that got all six local stations, using a mid sized fixed directional rooftop antenna.


But now that the leaves are on the large surrounding trees (or something), even my 10 foot mast above my 2 story home does not seem to get it. I spent a couple hours on the roof shouting to my son yesterday and there is no single direction that seems to work reliably for all six stations. And maybe theres even supposed to be 7 by now. I don't know if WB is on the air here, but I don't get it.


I absolutely loath rotor driven antennas, and don't want one. But what if I just put a 2nd antenna on the same mast, maybe a foot lower. I mean, if there are really only 2 directions I want then that would cover it. My WinTV-HD card allows each separate channel to be set up using one of two different f-connectors on the back of the card.


I know very little of antenna design. Is there any cross talk or interference or 'bad vibes' if I had the two antennas one on top of the other but pointed in different directions? I could have 2 completely separate cables into the house to the 2 f-connectors if needed. Or is there an even better way?


Any ideas?


- Tom





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Quote:
Don't underestimate the power of an IR controlled rotor. CM has one that is really smooth. You get a little box with a 3 digit LCD display that indicates the bearing location in degrees, and you can program up to 69 different presets for the channels & locations you want.
Ken -


Thanks. I guess I should have figured the technology would have evolved a bit since what I've used. And it at least has a remote. But I still think I'll keep it as a last resort.


- Tom


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[This message has been edited by trbarry (edited 09-05-2001).]
 

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Tom,


You are right about the channel surfing issue, it certainly can't be done without waiting for the antenna to finish it's move.


Another idea with the two antennas would be to use an A/B RF switch w/IR control. You would have to use two coax feeds from the antennas' location, and switch both channel & A/B input in short order, to surf.


If you do use two antennas, have you found the Jointenna info, yet? Somewhere on the ChannelMaster website it explains how you can put both signals on one coax, which may work for your application.


After reading your other posts about reception issues, I'm not sure what the problem really is. It could be the trees or your tuner card, antenna or cabling. I guess you have to start somewhere and narrow it down, so, have you tried the RF feed into a NTSC tuner? If you get decent analog reception, that may eliminate the antenna & cable as the problem.




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Discussion Starter · #10 ·
Even connected to separate cables, you still want to keep them apart. Otherwise, one antenna can "detune" te other. This is in accordance with the general guidance to keep the antenna that distance from any horizontal conductive surface (TV signals are horizontally polarized).


I believe Radio Shack still has an IR-controlled A/B switch. If I was in this situation I'd program the Pronto so that when you hit the icon for the particular channel, the macro would include the instruction to flip the switch.


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Sort of an offshoot of this - but -

I have a CM3614 VHF and a CM3021 UHF, both sitting on the same mast / rotor. The 3614 is right above the rotor, and the 3021 is about 12-18 inches above that. Is that too close ?


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[This message has been edited by Scooper (edited 09-05-2001).]
 

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Thanks everybody.


I guess I didn't explain one part of it properly. My WinTV-HD card effectively has the a/b switch built-in. If I were to run 2 cables all the way from the roof to the card there are 2 separate 75 ohm f-connectors on the back of it, switchable in software.


Any given channel is defined to be on either one or the other and can switch (with no moving parts http://www.avsforum.com/ubb/wink.gif ) just by changing channels.


But I suspect maybe something's wrong with my antenna cabling.


I went to radio shack and bough a cheap (non-amplified) set top antenna, choosing the one that had the most things I could tinker with. After a lot of that I was able to find a position that gets Fox & UPN, the two stations that are SW of me here in Northern Southfield. The only thing that works better than that position is sitting holding it in my lap and even here on the HDTV forum I am not that dedicated.


If I can rely on that after a couple days I'll climb back up on the roof and point the antenna SE. That should give me the best reception for the other 4 stations. I get 3 of the remainder anyway, but not PBS now, even though I used to with no problem. Except maybe ABC HD movie sound is still messed up but others also have that problem here.


I know FOX & UPN don't have any HD anyway but I wanted to record digital SDTV Buffy and I like to watch X-files, Allie, & Dark Angel even in 480p. Please don't flame me for watching non-HD but I like those shows.


If this combo settop/rooftop works then I might just leave it like this or I might add the 2nd antenna on the same mast. At least I now know to separate it some.


- Tom




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Quote:
Originally posted by trbarry:
I guess the reason I dislike rotors is because they are not automatic and you have to wait for them. It seems clunky and makes it harder to channel surf. As a computer software guy I tend to avoid and distrust all moving parts, whenever possible.
Your distrust is not unfounded. I used the CM 9521 rotator in my attic and it died after three days. Just wouldn't turn anymore. I returned it and got another one and this one has been going strong for two weeks. Hopefully I won't have any problems with this one.

Pics of my antenna installation


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Quote:
Originally posted by trbarry:
I spent a couple hours on the roof shouting to my son yesterday ...


Any ideas?
Try using your cell phone next time! Or those inexpensive FRS walkie-talkies!


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Tom


Sony SAT-T60 DirecTc>ic>Vc>oc> w/2.0.1

Sony SAN-24MD 24" elliptical dish
 

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Discussion Starter · #15 ·
Quote:
Originally posted by Scooper:

Sort of an offshoot of this - but -

I have a CM3614 VHF and a CM3021 UHF, both sitting on the same mast / rotor. The 3614 is right above the rotor, and the 3021 is about 12-18 inches above that. Is that too close?
If it's working for you right the way it is, then it's not "too close" for your situation, even if the antenna may not be performing exactly as designed.


With the 3021, the distance that counts is the distance to the lowest active element (the bow-tie), not the bottom of the screen. If you're 18 inches from the bottom of the screen, then you're probably close to 2 ft. from the bowtie.


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Well, last week I finally broke down and ordered a rotor.


And, just as washing your car can cause it to rain ... the next day the temperature dropped, the wind rose to frightening levels, and all the leaves fell off my trees.


Of course I now again have good reception on all channels, and a rotor somewhere in the mail. ;)


Maybe next spring.


It's nice that if I will have seasonably bad reception it will only occur during summer rerun season. :cool:


- Tom
 
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