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Discussion Starter · #1 ·
I live 30 miles South of Atlanta. I have a DTC100 connected by a single unbroken length of RG6/U to my original antenna which is a dual band R/S model 110" and my new antenna a Winegard 9085 Yagi. I am using the R/S as my VHF and passing it through the Winegard. My Antenna's are mounted on the rooftop of a 2 story house approx 35 feet high. I have a small wetlands with White Oak trees I must aim through, the patch of trees are approx 100 feet deep; then I have an otherwise unrestricted view of the broadcast towers downtown. The trees seem to have no effect on my signal. I have the same signal strenth now as when they had no foilage on them during the winter.


Atlanta has the following DTV channels. 10 - NBC; 19 - CBS;

27 - FOX; and 39 - ABC.


With just my R/S alone I had the following results:


Channel Signal

10 88

19 94

27 28-80 with signal lock only 25% of the time

39 25-30 with signal lock only 1% of the time


I then purchased the Winegard Yagi and I now get these results:


10 88

19 25-70 with signal lock 95% of the time

27 94

39 25-76 with signal lock 98% fo the time


I installed the Yagi yesterday and it was overcast. Today the weather was much clearer and I have yet to see a signal drop too low for a lock.


My biggest frustration is that I helped myself except for CBS/19 which has the best HD selection. I would like to cure my dropout problems. Is it time for an amp. If so won't that effect the 27/Fox signal?


please help!!!!????
 

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It sure sounds like for channel 19, the R/S signal and the Winegard signal are cancelling each other out. You need to either remove the UHF portion of the RS antenna, switch out the R/S antenna with a VHF-only (Winegard has these), or combine them with thr proper frequency-selective combiner such as a Channel Master Model 0549 coupler (check the Channel Master website).



------------------

You have a right to install OTA and dish antennas on property under your control.


See http://www.fcc.gov/csb/facts/otard.html
 

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If indeed the RS is interfering with ch. 19, you could use a UHF/VHF splitter/combiner ($9.99 at Radio Shack) to combine the antennas, rather than "passing through" (how are you doing this, does the Wineguard have a dedicated connection for passthrough?). This will keep the UHF signals from the RS antenna from interfering.


Bob


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Evil Gemstar: All your guide are belong to us!
 

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Randy,


I don't see why you should need more than one antenna.

It is my feeling that the simpler system is better than

the more complex system. At 30 miles, a 110" UHF/VHF

combo should work. I'm sure you have your reasons and

I would like to understand them.


I am very interested in DTV reception in the Atlanta

area, and have organized a YahooGroups based mail list

about this. We have a database and map with which we

keep track of the reception results for various types

of equipment and locations. Please join us:

www.yahoogroups.com/group/ahdtv
 

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Local antenna groups is a great idea. I am on the east side of Corte Madera in Marin county, north of San Francisco and am interested in finding the best antenna for OTA in this area. The local stores are clueless. Anyone in this area want to join a discussion group?
 

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By your description it sounds like you have incorrectly connected your two antennas. You cannot put two antennas in parallel by connecting their leads together and then continuing on to your receiver. Electrically you are in no-mans land. If you are going to use 2 antennas, you must combine them with a proper combiner that maintains the design impedance of antennas.


When you say

"I have a DTC100 connected by a single unbroken length of RG6/U to my original antenna which is a dual band R/S model 110" and my new antenna a Winegard 9085 Yagi."


You imply that you have somehow cut open the RG6 coax and made connections to the middle antenna. If indeed this is what you have done, you have really violated the integrity of your antenna system.


Also it was a bit unclear whether you tried the Wingard 9085 alone or only connected with the RS antenna. Obviously Channel 10 is VHF and the UHF antenna is not designed to pick up that station but it may get enough signal to be ok. The standard UHF Yagi antennas typically are optimized for the middle of the band and the low end will have several db less gain than the middle. The beamwidth is also wider at the low end giving you a little more potential multipath probs.


At this point I think we need to clearly understand how you have connected the antennas and try to help you get them setup correctly.


..Doyle
 

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Discussion Starter · #7 ·
Sometimes no matter how hard I try to be clear it still comes out muddy.


Thanks everyone for your suggestions so far. But let me try to be clearer about the hookup.


The Yagi is on the top of the mast with the R/S 4 feet below it. I ran RG6 Coax from the R/S to the Yagi. Winegard has a pass thru connector for VHF. Then a seperate RG6 is running from the Yagi to the DTC100. I hope that makes it clearer. I guess the issue is does the Winegard "passthru" the VHF and the UHF from the R/S antenna or does it only accept the VHF portion of the signal from the R/S antenna.


I have a call into Winegard Tech support and I'll report what they suggest.


I will go home tonight and remove the Radio Shack and see what happens.



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

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The RS is a UHF/VHF antenna, right? If so, you should block (filter) the UHF band before you can combine the signals.


SM
 

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Quote:
Originally posted by Randy:
Sometimes no matter how hard I try to be clear it still comes out muddy.
Randy, You did good, sometimes we ask questions to make certain of our answers (which comes out clear as mud sometimes).


I have the Winegard info sheet, [WC-62, rev. 1/93], and the engineering specifications sheet on the CA-9085. They do not indicate if the CA-9085 module has a UHF trap on the pass through or not. If it does not, then the above replies apply, if it does, then we will punt and see what we can come up with.


UPDATE

==============

From the Winegard site: Precise director spacing combined with efficient corner reflector system. Weak UHF signals captured and reflected with minimal loss to driven element for increased uniform gain on all UHF frequencies on Channels 14-69. Features 75 ohm built-in VHF coupling jack.


Based on this info, I would proceed as others have already suggested.


------------------

Wendell

Technical Services Supervisor

MAETV


[This message has been edited by Wendell R. Breland (edited 05-09-2001).]
 

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I concur with Doyle.


You cannot simply hook up two dissimilar antennas and expect them to work correctly (as I think you have found out).


Stacking two identical antennas a specific distance apart with 1/4 wavelength splitters can be used to add 3 dB more gain to your overall antenna system.


What's likely happening here is that two different UHF signals are combining from each antenna and introducing out-of-phase problems. The signals are literally cancelling each other out.


Your best bet is to use a UHF-only and VHF-only antenna with the appropriate combiner, or (better yet) use two separate feedlines.


If you need to use one feedline, chose a VHF antenna that has extremely low response in the UHF band, and a UHF antenna that has low gain in the VHF band. UHF-only and VHF-only preamps will also help boost gain in their particular band segments.


KC
 

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Discussion Starter · #11 ·
I just off the phone with an antenna designer at Winegard.

The 9085 signal combiner box does reject UHF and only passes VHF. He thinks that it is the reflection from the other antenna that is causing my problems. (Smart group we have here).


I asked about a preamp and he say's it will probably enhance the bad with the good.


I'm going to take down the r/s and see if it is better. If it is I guess I'll buy another VHF only antenna.(or could I take a hacksaw to the UHF boom?????)


I thought I would pass on some other comments he made:


1. They are 75 miles from the closest DTV signal and they don't have much experience with Digital signals yet.


2. In three weeks they are releasing a new line of HDTV antennas?????see item #1.




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

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If all you need is channel 10 on VHF, can't you get a single channel 10 VHF antenna and combine it with a UHF antenna?


Glenn
 

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This guy could be a valuable resource. Did you tell this Winegard engineer about the Forum????? He would make a great addition.


Too bad he doesn't have much experience with Digital. Did he make any comments or give descriptions of the new line of antennas?
 

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That makes a lot more sense. Essentially you have a UHF/VHF splitter which means one is a high pass filter (UHF) and the other is a low pass filter (VHF). I think taking down the RS antenna is a good start. You have had no trouble receiving your single VHF (10) channel. I would see if the Winegard gives you good signals on all of the UHF channels and by the way, it should. Additionally, you may find that the UHF antenna actually picks up the VHF channel 10 ok. If not, then you can decide which way you want to go with combiners or additional antennas. I would stay away from amplifiers at this point in time. You are only 30 miles away and if you have a clear shot you shouldn't need an amplifier. Combining a separate VHF only antenna should give you your desired results especially if the combiner is a UHF/VHF combiner with good rejection of the other band.


..doyle
 

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In Dallas we have the same sort of DTV channel configuration that you do in Atlanta: one station (ABC) on VHF and the rest on UHF. I have a VHF antenna on my roof which has done a great job of receiving all the analog VHF channels, and will also beautifully pull in two or three of the strongest UHF channels (but does a poor job on most of the other UHF stations).


I have not yet bought an HDTV STB, but I'm getting close. I'm wondering what I'm going to need to do about antennas. Should I expect that I will need a second, UHF-optimized antenna? If so, how should I combine them?


(I'm about 20 miles from the towers in Cedar Hill, with significant tree cover between the existing antenna and the towers)


[This message has been edited by lhl12 (edited 05-09-2001).]


[This message has been edited by lhl12 (edited 05-09-2001).]
 

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lhl12,

If cost is an object then start with what you have and make an assessment of what you need to do to improve it once you are setup. There is plenty of help here in the forum and a number of guys in the Dallas area so you should be able to get some good inputs. It is difficult to give much advice until you get started. Keep us posted.


ps- Give us a handle, lhl12 is hard to type and hard to pronounce.


..Doyle
 

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Discussion Starter · #17 ·
Ok everyone,


It worked!!! here are my results, with the past results for reference:



With just my R/S alone I had the following results:


Channel Signal

10 88

19 94

27 28-80 with signal lock only 25% of the time

39 25-30 with signal lock only 1% of the time


I then purchased the Winegard Yagi and combined it with the R/S then I got these results:


10 88

19 25-70 with signal lock 95% of the time

27 94

39 25-76 with signal lock 98% fo the time


Now with the Winegard Yagi alone I get:


10 0

19 94 no fade

27 94 no fade

39 82 - 86 no fade


You guy's know your stuff!


Now I need a VHF only antenna. Any recommendations? How far apart should I keep the antennas to keep the same thing from happening again? Or was this only a symptom of a Dual Band antenna? I was thinking of buying a 10 ft mast extention which would put the two approx 14 apart.


Here's what I found interesting;

When I had the antenna's combined the signals I got would not change much when I tried to fine tune the direction. Now, I find it is very tuneable. It is very directional now!


I also tried to put a splitter on the main RG6U line so my wife can record with the vcr. My channel 19 signal suffers the most. It went from 94 to 82. Any suggestions?


What I want to do is split the signal to three separate locations. I figure the best way is to use one 2 way splitter with one split lead going straight to the reciever and the other lead split again to the other two bedrooms. Does this sound right or should I get a distribution amp?



BTW-I wrote a personal email to the Winegard antenna design engineer and asked him to join us on the forum.



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

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Quote:
Originally posted by [email protected]:

For what it's worth, the DTC100 signal meter does not indicate strictly signal strength. I believe they sample the BER in some fashion.
I think that's true of all STBs. They have an AGC in the front end, so the receiver chip has no way of knowing what the signal level is.


One of these days I'm going to wage a campaign to have it referred as "signal quality meter" or something like that.




------------------

You have a right to install OTA and dish antennas on property under your control.


See http://www.fcc.gov/csb/facts/otard.html
 

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Quote:
Originally posted by Randy:
Now I need a VHF only antenna. Any recommendations? How far apart should I keep the antennas to keep the same thing from happening again? Or was this only a symptom of a Dual Band antenna?
Randy, This is assuming you want to stick with Winegard, then check out Winegard VHF Antennas . Channel Master recommends a minimum of 30" spacing between VHF and UHF antennas.


Every time you split the signal you lose a little more than half of the signal you had to start with. You have a couple of options, use the Winegard DA-1411 4-Set Booster Coupler or one of the Winegard Pre-Amps. I would use one of the models that has less than 20dB of gain.


------------------

Wendell

Technical Services Supervisor

MAETV
 

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I'm the originator of the other thread. I've learned a lot since I started that thread, but still have some problems when it is windy. There's not much left to try.
  • I've installed RG-6.
  • I've eliminated all upstream splitters.
  • I've removed the amplifier.
  • I've tested a variety of (horizontal) orientations.


When there is no wind:
  • 10 (NBC/11) never fails
  • 19 (CBS/46) never fails
  • 39 (ABC/02) never fails
  • 27 (FOX/05) never fails



When there is some wind:
  • 10 (NBC/11) never fails
  • 19 (CBS/46) never fails
  • 39 (ABC/02) watchable
  • 27 (FOX/05) not watchable


When there is considerable wind:
  • 10 (NBC/11) never fails
  • 19 (CBS/46) watchable
  • 39 (ABC/02) not watchable
  • 27 (FOX/05) not watchable


Fortunately, the most likely to fail come in best on analog, and I've resorted to that from time to time.


Reviewing the polar plots for some of the antennas on the Winegard site mentioned above does not indicate that a larger antenna will yield much better directionality. Therefore I don't think that will help with multipath and therefore I don't think that will help at all.


I'm considering testing with some attenuation, just to learn more about the signal strength factors. But my experience is that I have neither too much nor too little signal strength. I think I have a multipath problem, and neither attenuating nor amplifying will help that (I took down my amplifier as I mentioned above).


The only meaningful thing I think I can do is install a rotor. The testing I've done indicates that I lucked into the exact best position early on. Even a few degrees change makes things worse (it has to be windy to test, and it takes a lot of dedication because the better/worse determination can only be made through statistical consideration of all 4 channels, and also some amount of ladder climbing for each test). Still, I can do better testing with a rotor, I could determine best orientation for each channel independently (but only need to mess with that when it is windy), and I could presumably get better analog reception on stations which don't broadcast in digital (something I really haven't expored to this point).


BTW, I live 8-9 miles from the transmitters NE in Atlanta.


Thanks to people here for so much help to me, and the help provided to others like Randy has also been helpful to me.


-CB- http://www.avsforum.com/ubb/smile.gif
 
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