New set up in Canton Ohio

timotb · 18-Dec-2011, 10:43 PM

http://www.tvfool.com/?option=com_wr...4033328f8cf7ae

I bought a cheap 125 mile antenna on ebay, The WA830TG. Reception is good when the rotor doesn't get stuck. Otherwise I have to look outside to see the current position and move it guessing the correct azimuth for the desired channels.

It appears I have two strong areas of channels, 310 degrees and 070 degrees. Forget channel 47, its all Religion. Im interested in WJW and WUAB, both should be strong but I receive neither.

I will probably send this antenna back since I have 60 days to try being the rotor gets stuck often. Finding a quality antenna is my goal.

GroundUrMast · 19-Dec-2011, 8:30 PM

Your experience with WUAB in particular, continues to build the case against using a low or moderate gain antenna followed by a high gain amplifier in the mistaken hope that the amplifier will make the antenna perform like a high gain antenna.

Return the WA830TG, get your money back. (Perhaps post a review if you can.)

There are several ways to approach your situation. Two ideas come to mind:

1) Two antennas, each cabled to the TV separately where an A/B switch or, if the TV has multiple inputs, two DTV tuner boxes give you the means to select the desired antenna.

To receive WUAB & WJW reliably, I'd use no smaller than a Winegard HD7694P pointed toward 335°. The HD7698P would not be overkill IMO. If the cable length is 50' or less and you are not going to split to multiple sets, try this with no amplifier.

Looking toward 75° compass, a 4-bay panel antenna will do well unless you want to receive WYTV and/or WYFX.

U4000, DB-4, DB-4e, CS4, CM-4221 or HD4400.

http://www.antennacraft.net/Antennas/AntennasUHF.html
http://www.antennasdirect.com/store/...-Antennas.html
http://www.channelmaster.com/Channel...ntenna_s/3.htm
http://www.winegarddirect.com/cview....nly%20Antennas

(The DB4e is optimized for use in the new post 2009 UHF band and so has more gain on the lower channels than the previous DB4)

If you are interested in either WYTV or WYFX, go with an Antennas Direct XG91 or Winegard HD9032 instead of a 4-bay antenna.

2) A single antenna with rotator. This can work well for a single TV. It gets frustrating for views who don't have control of the antenna rotator. The Winegard ...7694 or larger would be my choice. Re. a rotator, the NTE U-106 plus the TB-105 thrust bearing is a strong consumer grade rotator system.

Electron · 19-Dec-2011, 8:41 PM

The simple dependable cost efective way to receive the digital tv stations all around the compass is to install a Channel Master CM3000A antenna above the roof. http://www.channelmasterstore.com , http://www.solidsignal.com , http://www.amazon.com

GroundUrMast · 19-Dec-2011, 9:18 PM

Quote:

Originally Posted by Electron

The simple dependable cost efective way to receive the digital tv stations all around the compass is to install a Channel Master CM3000A antenna above the roof. http://www.channelmasterstore.com , http://www.solidsignal.com , http://www.amazon.com

I'm quite skeptical that an omnidirectional antenna would reliably receive WJW and WUAB.

timotb · 19-Dec-2011, 10:45 PM

Groundurmast might have the best solutions. I was hoping for a simple, one antenna set up similar to what I already have but a little higher quality. Doesnt seem to be any. Thanks to everyone, and Im still open to ideas.

Electron · 20-Dec-2011, 7:50 AM

Install a http://antennacraft.net , HDMS9100. High quality rotating antenna.

GroundUrMast · 20-Dec-2011, 5:40 PM

The Antennacraft product line is reputable and the manufacturer provides reasonably helpful performance documentation. http://www.antennacraft.net/pdfs/HDMS9100.pdf

Based on this published information, I'm lead to believe that the net high-VHF performance will be a negative number. The antenna gain is spec'd at -6.4 dBd and the integral amplifier NF is 3.7 dB (H-VHF band). At best I expect the result will be a reduction of received NM by about 10 dB.

WJW, real CH-8 is predicted to arrive at a NM of 18.4 dB. Therefor the expected net NM at the output of the antenna will be about 8.4 dB. That's begging for unreliable reception results IMO. And this does not consider how much edge path fading and multipath will be present.

Contrast this against the performance of the HD7694P. Conservative interpolation of the manufacturer's performance specifications puts the gain at about +8 dBd on channel 8. Using no amplifier, there will be no reduction of net NM due to amplifier noise. For WJW, the expected net NM will be 18.8 + 8 = 26.8 dB. I think adding a net of 18 dB NM significantly improves the chance of reliable reception of WJW.

Electron · 21-Dec-2011, 2:16 AM

Bob called to tell me that with the reception of HDMS9100 take a look at these figures. For reception of WJW on channel 8 the NM(dB) is +18.4 and the antenna gain with out the built in preamp is -6.4 so that makes the signal strength 12 NM(dB). The amplifier gain is 16 dB on the VHF channels and then subtract the 3.7 noise figure , making the amplifier gain 12.3 dB. So while it is true that a amplifier does not make signal , the amplifier will at least carry the 12NM(dB) signal from the antenna through the coax with no loss of the 12NM(dB). So 12 , while not a real hot number , it is Ok. . . And then if WJW 21 is on the air , the NM(dB) # is 14.4 . The antenna gain is +2.5 making the number 16.9 . The UHF amplifier gain is 20 dB and then subtract the 2.9 of noise and that leaves 17.1 dB. So the 17.1 dB amplifier gain will at the very least carry the 16.9 signal through the coax to the tv with 16.9 at the tv. The FCC reference point number for reliable reception is 0 NM(dB).

Electron · 21-Dec-2011, 2:22 AM

About how long is the coax run from the antenna to the Tv??

GroundUrMast · 21-Dec-2011, 4:36 AM

Quote:

Originally Posted by Electron

Bob called to tell me that with the reception of HDMS9100 take a look at these figures. For reception of WJW on channel 8 the NM(dB) is +18.4 and the antenna gain with out the built in preamp is -6.4 so that makes the signal strength 12 NM(dB). The amplifier gain is 16 dB on the VHF channels and then subtract the 3.7 noise figure , making the amplifier gain 12.3 dB. So while it is true that a amplifier does not make signal , the amplifier will at least carry the 12NM(dB) signal from the antenna through the coax with no loss of the 12NM(dB). So 12 , while not a real hot number , it is Ok. . . And then if WJW 21 is on the air , the NM(dB) # is 14.4 . The antenna gain is +2.5 making the number 16.9 . The UHF amplifier gain is 20 dB and then subtract the 2.9 of noise and that leaves 17.1 dB. So the 17.1 dB amplifier gain will at the very least carry the 16.9 signal through the coax to the tv with 16.9 at the tv. The FCC reference point number for reliable reception is 0 NM(dB).

Thanks for discussing this.

Looking at the predicted NM of WJW, real channel 8, we agree it's 18.4 dB per TV Fool.
We agree that the vendor specified gain of the HDMS9100 is -6.4 dBd in the high-VHF band.
We agree that the net NM at the antenna output, ahead of any amplifier would therefor be 12 dB.

At this point we seem to take different paths. I subtract the noise figure of the amplifier, 12 dB - 3.7 dB = 8.3 dB NF net at the output of the amplifier.

Assuming the amplifier is operating within it's linear region, the desired input signal & noise is amplified equally, by the gain ratio of the amplifier. The amplifier adds it's own noise to the combination of input signal+noise resulting in the total noise output increasing by the amplifier gain + noise figure. The net result is a lower noise margin at the output of the amplifier.

(I think we both agree that the amplifier gain is sufficient to overcome cable and splitter loss on the output side of the amplifier.)

If Bob says that you simply subtract the NF from the gain of the amplifier, I respectfully disagree. (Is Bob an Antennacraft engineer?)

Re. "The FCC reference point number for reliable reception is 0 NM(dB)", Using 0 NM as the design target leaves no margin for noise, fading, multipath or imperfections in the receiver. There are many examples in this forum where people have much better NM predictions, yet have trouble obtaining reliable reception.

http://transition.fcc.gov/Bureaus/En...7/fc97115a.pdf

pp A3, section III implies that noise in the low VHF band requires at least 13 dB better net NM (per TV Fool prediction corrected for antenna gain and system losses including amplifier NF) than the UHF band.

Noise in the high-VHF band is implied to be 5 dB higher than the UHF band.

Please correct me if I'm wrong.

Again,

Thanks for discussing this.