180 degrees out of phase antenna!!!

jonnyd97

DTVUSA Member
#1
Hello men:

Thanks to the thoughtfulness and time that you guys have taken to respond to my previous posts and questions I have got my HD7698P up and running and pulling in the NYC stations from 30 Rockefeller Station in New York, here in farmland Connecticut! So I thank you gentlemen for that.

Now, in typical American fashion, I am getting greedy haha. Upon experimenting with the antenna, I can get a good amount of NY stations, *OR* I can get the key important CT stations. My TV Fool report indicates that Hartford CT is 180 degrees away from New York City.

Therefore, my question is, how may I receive *both* sets of broadcasts?

May I:

1. purchase an additional HD7698P antenna,
2. install the second antenna on the opposite end of my roof pointed toward the other stations,
3. using the exact same lengths of RG6 Quad Shield, wire both antennas to a CC-7870 combiner,
4. run the "combined" signal through my existing (as of today) RCA preamplifier then distributed through my house to all sets.

Or, how would *you* do it? I appreciate any response you may have. Your responses have already yielded me a lot of results in my quest to *CUT THE CORD* and save some money for my growing family!

Regards,
Jon
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#2
Jon,

Any two (or more) antennas can share the same antenna mast but if possible, seperate them by at least three feet to reduce interaction between them. You suggested using two identical antennas and YES they could be combined on a single coaxial cable, but have you engineered the consequences? If so, you would not be here on this Forum asking questions, you would be teaching us.

Please scroll down to "The Two Antenna Trick" here: Stacking multiple antennas

If you use two (non-combined) antennas I suggest two coaxial feeds and an A-B switch. I think the best option would be to use an antenna rotator using your existing antenna that you already know receives both antenna farms.

Think about it: the time it takes to rotate your antenna during a commercial break between shows is less time than a bathroom break. Works for meeee!

Jim
 
#3
Therefore, my question is, how may I receive *both* sets of broadcasts?

1. purchase an additional HD7698P antenna,
Looks like all the Hartford CT stations are on UHF, you shouldn't need another large/expensive 7698 to grab those stations. A smaller UHF only antenna should do the trick for Hartford.

You will likely need to run a separate cable to each outlet that you would like to have the Hartford stations & use an A-B switch. Combining 2 antennas onto one down lead usually yields poor results. Of course you could use a rotor on the 7698, but that can cause conflicts with multiple outlets.
 
#4
3. using the exact same lengths of RG6 Quad Shield, wire both antennas to a CC-7870 combiner, -
Cable length doesn't matter for this application. The CC7870 is simply a 30 year old splitter design, nothing special. You can do the same thing with a $6 splitter from a store.


4. run the "combined" signal through my existing (as of today) RCA preamplifier then distributed through my house to all sets. -
Sure, you can run it through there. Unfortunately, there's no way of knowing if it's going to work until you actually try it.

The A-B switch or rotor ideas will work since they don't rely on chance but will be less convenient.
 
#5
This subject has recently been discussed in the thread Need help with antennas started by dennismck. Read it if you haven't. I doubt any of us can add much that was not mentioned in that thread.
Steve
 

jonnyd97

DTVUSA Member
#6
Okay thank you fellows! I think it might be the mathematical opinion of you guys that approximately 50% of my signal will be *lost* if combining two antennas into one downlead, even if by using the glorified splitter known as the CC7870. Does anyone disagree with this assumption? Thank you again.
 
#7
You will loose a bit more than 50%, typically 3.5 to 4 dB. 50% = -3dB.

That's before any potential mischief from phase cancellation shows up should both antennas pick up the same signal.
 
#8
Please scroll down to "The Two Antenna Trick" here:
There's also the two antenna / two tuner trick: http://www.dtvusaforum.com/dtv-hdtv...7244-combining-two-unlike-antennas-kicks.html Navigate to post #33.

If you use two (non-combined) antennas I suggest two coaxial feeds and an A-B switch. I think the best option would be to use an antenna rotator using your existing antenna that you already know receives both antenna farms.
Whew! Two completely different suggestions in one paragraph. I got whiplash!

Think about it: the time it takes to rotate your antenna during a commercial break between shows is less time than a bathroom break. Works for meeee!
No way. Wouldn't work for me. I'd break the rotor in a week.

Jus messiinwitcha,
Rick
 
#10
Here is what I might try for my "secondary" antenna, with which I hope to receive six (6) total channels, including subchannels.

I will run the downlead from my roof into my attic. Into a six-way splitter. Into six DTT901 converters. Each of the converters is tuned to a separate channel (hence the total of six units). The output of each of the six (6) converters feeds into separate Modulators. I would tune the output of the modulators to Analog 51 thru Analog 56, perhaps. I will combine the output of all six Modulators. I will run that coax to my television.

At the television I will combine the coax from my "primary" antenna and the coax from my Modulator. My "primary" antenna should provide the "primary" channels via their virtual channel numbers. My "secondary" antenna should provide the other channels by tuning the TV to analog channels to A-51 thru A-56.

You like?
 
#11
Men,

If you do not like my Modulator idea above then how about this idea inspired by my new expert friends here at DTVUSA:

I can run the downleads from each of the two (2) antennas to my living room. I can plug each of the two coax cables into their own HomeWorx HW-150 Converter box, chosen because of its HDMI outputs. So, yes, I would have *two* (2) converter boxes at the TV location. When my wife points the remote at the HW-150, the channels will change on *both* converters. Then if she does not like the reception she is receiving then she can grab the Sony TV remote and change inputs (HDMI-1 versus HDMI-2) on the television to choose which antenna she is watching, New York versus Connecticut.

Sounds idiot-proof and technically feasible to you?

Which antenna is as powerful as the HD7698P but only receives UHF? The 8200?

Thank you!!!
 

Trip

Moderator, , , Webmaster of: Rabbit Ears
Staff member
#13
Part of the problem is that you have at least a few stations on the same channel that would wipe each other out. WTIC-31/WPXN-31, WCBS-33/WFSB-33. So if you try to combine the two antennas, those signals will be lost entirely.

- Trip
 
#14
Trip! Thank you for that note. I had not yet considered that interference issue! You are referring to my TV Fool report that indicates the interference to which you refer.

All the more reason that I might have to have two (2) separate converter boxes at my television location. So that each converter will only receive signal from its corresponding antenna!

Wow if I had tried to combine the signals without hearing from you first then I would have completely had *no* chance in receiving *either* CBS station, the CT FOX station or the CT ION station!

Why would a network (CBS) transmit on the same frequency in adjacent markets? And furthermore wouldn't FOX and ION be upset that they are competing with each other? In other words if I only use one (1) antenna then I will only receive one channel *or* the other!

Thanks
Jon
 
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Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#15
Jonnyd97,

You said a 'modulator'. Are your referring to something like a Channel Plus SVM-24? Channel Plus SVM-24 S-Video Modulator 4 Channel - Smarthome

Jim

PS I have a similar plan but we will both end up with analog (almost SD) video on those channels. The channels you choose to use must not be adjacent: if 35, 41, 44 and 50 are not occupied in your area, use them. Adjacent channels like 35 and 36 will not work because they will interfere with each other. Lower channels are better IF they are available BUT remember the necessity to NOT have adjacent channels. Channel Plus units have plenty of RF output for an entire home.

PPS I have one and I am planning to add it to my system for my bird feeder cam, my front door cam et al. I have thought about using one channel as a weather-cam on one of my antenna masts. Think about that: I'd never have to look out the windows to see current weather (crazy, huh?)! Too funny.
 
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#16
Jim I think I have since abandoned the idea of using modulators but if I did use them then I would have to take heed to your suggestion and get some kind of modulator that can manage HD signals!

Jon
 

Jim5506

DTVUSA Member
#18
Just a note on combining 6 NTSC modulators into a coax line - there is considerable bleed over on NTSC channels - even the FCC did not put analog TV stations on adjacent channels in the same area usually a 2 channel separation is recommended.

Cable operators use high quality equipment to minimize co-channel interference so they can do it.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#19
Jim,

I didn't know a 12 mHz gap was ever recommended for FCC 'type accepted' receivers. In the analog days I had locals 4 and 5 with the 2 mHz aviation gap and I saw no competition from any of the three services.

Jim
 
#20
I can run the downleads from each of the two (2) antennas to my living room. I can plug each of the two coax cables into their own HomeWorx HW-150 Converter box, chosen because of its HDMI outputs. So, yes, I would have *two* (2) converter boxes at the TV location. When my wife points the remote at the HW-150, the channels will change on *both* converters. Then if she does not like the reception she is receiving then she can grab the Sony TV remote and change inputs (HDMI-1 versus HDMI-2) on the television to choose which antenna she is watching, New York versus Connecticut.
Forgot to mention in the duplicate post from other thread: Not sure why you need TWO converter boxes for this to work. Your TV has a tuner, right? Use it!

Which antenna is as powerful as the HD7698P but only receives UHF? The 8200?
There's a few, but I'm all tired out from the duplicate posts. :rolleyes:

Saw Palmetto ... Jim, I'm straaaaaaaaining to see the relevance. :behindsofa:

Rick
 
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