Is it good enough?

[harold]

http://www.tvfool.com/?option=com_wr...f1f0e11b178bfc


Will winegard 8200 antenna pick up channels from 48.8 miles with NM (dB) -12.5 Pwr(dBm) -103.5 and path1 edge?
Some co channels and adjacent channels are closer at 352 & 300 degrees

[ADTech]

Why would you select a large, all-channel antenna when you have no low VHF stations in your area? Those really long elements on the back are for channels 2-6 and you have none of them.

Please identify the specific station(s) you're concerned with.

[harold]

I have the 8200 left over from analog and didn't know I had towers close.

[harold]

Special channel k30jp -11.1 nm dB 48.8 distance and 334 degrees. What rooftop at 27 height would work?
Thanks!

[rabbit73]

Hi, Harold:

Is it good enough?

Probably not for 100% reliable reception under all conditions, but it has been done at times because the tvfool report is only a computer simulation. If you are willing to take a gamble, go for it. You can see how the signal runs out of energy by the time it reaches your location. It is in your favor that you are in the "wide open spaces."

What rooftop at 27 height would work?

You would need to go to 200 ft to get your K30JP NM up to -10.2:
http://www.tvfool.com/?option=com_wr...f1f051db74fc37

and up to 400 ft to get it up to +1.4 dB:
http://www.tvfool.com/?option=com_wr...f1f06b12a09a2f

A Noise Margin of zero is the weakest signal that can be received. You can add your antenna gain of about 13 dB, which brings the NM up to +1.9 dB. You can also add your preamp gain, but you must subtract its noise figure (NF), because its internal noise reduces the SNR (Signal to Noise Ratio) of the signal. This should give you enough gain to overcome the coax loss and will improve the system noise figure.

Disclaimer: I can't guarantee that this will work; you are on your own. I never want to discourage anyone from doing antenna experiments. I always learn something from my antenna experiments, especially the ones that don't work because I have to figure out why they didn't.



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

[Billiam]

Rabbit73. When I lived in a small town some 40 miles east of Kansas City, I was able to reliably and daily pick up a very weak UHF signal with a NM of minus 16 and it was 2 edge. Once I installed a MXU 59 and later a HBU 55 I was able to receive it all the time with a pre amp.

That being the case it may be possible for the OP to pick up that station if he's lucky. A pre amp will certainly be needed to determine if it can be received reliably.

[rabbit73]

Billiam:

Thanks for the benefit of your experience. I will modify my post to give Harold a little more hope, but not too much.

[ADTech]

A 410 watt station on a 410' tower almost 50 miles away is pretty much going to be a "no-show", no matter what you put up in the air or how high you put it.

[rickbb]

Not to mention that according to the terrain profile he's down in a hole from that tower.

[rabbit73]

I have had some success with very weak signals. A few years ago I tried tvfool reports for my location by zip code, address without height, and address at 5 ft height. I also did a recent update with NMs for 5 ft, which is the height of my antenna because it is in the common area, not my controlled area.

Real       tvfool-zip   tvfool-address  address 5 ft  Update 5 ft 5/7/2015
 CH         dBm  path     dBm  path       dBm  path    NM(dB)  dBm   path
  7 WTPC   -41.9 LOS     -74.0 2Edge    -81.0 2Edge     9.9  -81.0  2Edge
  9 WSKY   -58.1 LOS     -88.2 2Edge    -95.5 2Edge    -4.6  -95.5  2Edge
 11 WGBS   -73.8 LOS     -98.9 2Edge   -114.6 2Edge   -23.8 -114.6  2Edge
 13 WVEC   -38.6 LOS     -71.1 2Edge    -78.0 2Edge    12.8  -78.0  2Edge
 16 WHRO   -32.4 LOS     -62.3 2Edge    -72.2 2Edge    18.6  -72.2  2Edge
 17 WKTD   -50.0 LOS     -87.9 2Edge    -95.4 2Edge    -4.6  -95.4  2Edge
 20 WUND   -93.8 2Edge  -117.9 Tropo   -117.9 Tropo   -27.0 -117.9  Tropo
 22 WRIC   -57.9 LOS     -87.7 2Edge    -94.3 2Edge    -3.5  -94.3  2Edge
 25 WTVR   -60.4 LOS     -90.1 2Edge    -96.5 2Edge    -5.6  -96.5  2Edge
 26 WRLH   -58.5 LOS     -88.5 2Edge    -95.1 2Edge    -4.2  -95.1  2Edge
 29 WVBT   -32.7 LOS     -69.2 2Edge    -77.5 2Edge    10.6  -80.2  2Edge
 31 WAVY   -32.8 LOS     -66.2 2Edge    -75.6 2Edge    15.2  -75.6  2Edge
 33 WTVZ   -33.3 LOS     -63.4 2Edge    -73.2 2Edge    17.6  -73.2  2Edge
 40 WTKR   -33.9 LOS     -64.4 2Edge    -74.0 2Edge    16.9  -74.0  2Edge
 42 WCVE   -62.1 LOS     -92.6 2Edge    -98.7 2Edge    -7.9  -98.7  2Edge
 45 WNLO   -55.3 LOS     -93.4 2Edge   -101.7 2Edge   -10.9 -101.7  2Edge
 46 WPXV   -35.4 LOS     -67.0 2Edge    -76.4 2Edge    14.4  -76.4  2Edge
 50 WGNT   -34.8 LOS     -69.6 1Edge    -79.3 1Edge     8.5  -82.4  1Edge

What prompted me to make some tests, was that I had been asked if there was a way to hunt for and measure channels that had been missed during a tuner scan. If the tuner doesn't pick them up, we don't know why, and what could be done to receive them.

For the first test I connected my CM4221 antenna, which is outside close to ground level, to my Sadelco 719E signal level meter (SLM) with a short coax jumper (SCJ), and took some readings of my channels.

CM4221 > SCJ > 719E SLM

For the second test I added my CM7777 preamp to see if I could read the weak channels.

CM4221 > SCJ > CM7777 > SCJ > CM0747 Power Supply > SCJ> 719E SLM

Real      Test 1          Test 2      Amp Gain 
 RF           Equiv           Equiv
 CH    dBmV    dBm     dBmV    dBm       dB 
 16    -6.9   -55.7    +19.0  -29.8     25.9
  9   -10.2   -59.0    +13.1  -35.7     23.3  
 31   -12.2   -61.0    +12.1  -36.7     24.3
 33    -9.0   -57.8    +14.8  -34.0     23.8
 40    -9.0   -57.8    +15.1  -33.7     24.1 
 46   -19.9   -68.7     +6.2  -42.6     26.1
 50   -22.0   -70.8     +2.9  -45.9     24.9 
Amp Gain is the difference between the two tests and 
varies because the signal strengths changed between tests.

I was able to measure a few weak ones that don't always show up after a scan with the preamp:

                                           Signal Strength at Antenna 
                                           Terminals before 24 dB Preamp
                                                  dBm                                        
 17     NA      NA     -10    -59        NA       -83
 19     NA      NA     -26    -75        NA       -99
 22     NA      NA     -20    -69        NA       -93
 42     NA      NA     -25    -74        NA       -98
 45     NA      NA      -8    -57        NA       -81

Antenna enclosure on porch for CM4221 and folded dipole for VHF-High in attachments. The signals have to travel through the openings in the decorator blocks on their way to the antenna. Not much attenuation for UHF, but a lot more for VHF. The openings act like a high-pass filter, as their size is related to wavelength.

[harold]

Thanks guys for all your imput. I'm going to try pointing at 333 degrees and see if I can get stations from 300 & 355 degrees.

[rabbit73]

To make some more weak signal tests I set up my SONY KDL22L5000 TV indoors to see what I would get from a scan:

CM4221 > 6 ft RG6 > CM7777 > 50 ft RG6 > CM4707 Power Supply > 3 ft RG6 to TV or SLM

The gain of the preamp and the loss of the coax gives a signal 21 dB stronger at the output of the CM4707 than at the antenna; I measured it so that I can calculate the signal strength at the output terminals of the antenna from measurements indoors.

I didn't use a splitter to feed the TV and signal level meter because I wanted max signal strength; I just substituted one for the other. When I am comparing the sensitivity of two tuners, then I use a 4-way splitter to feed the two tuners and my SLM to bring them to the cliff with an attenuator.

I first measured the strength of some signals with my 719E SLM to check the system. The 4221 was used for UHF and a folded dipole cut for CH13 for VHF:

Real           Equiv
 CH   dBmV      dBm
 7    +1.5    -47.3
 9    -5.0    -53.8
11   -10.0    -58.8
13    +4.0    -44.8
16   +21.5    -27.3
29   +11.5    -37.3
31   +11.5    -37.3
33   +12.1    -36.7 
40   +14.2    -34.6
42   -25.0    -73.8 very unstable, antenna aimed in wrong direction
46    +2.3    -46.5
50    +3.5    -45.3

The noise floor measured about -10 dBmV (-59 dBm) on VHF-Low and about -20 to -25 dBmV (-69 to -74 dBm) on VHF-High, which doesn't leave quite enough margin for reliable reception of CH11. I need to improve my VHF-High antenna.

The tuner scan gives the channels in virtual number order:

Virtual Real Errors   SNR   Sony Signal Strength  Out of Ant OTA Signal 
  CH    CH             dB    Scale   dBmV   dBm       dBm       dBm **   

 2.1    20   0-6971  13-15   58-61  -26.5  -75.5     -96.5    -108.0
 3.1    40     0      25       79   >-4.0 >-53.0    >-74.0    >-85.5
 4.1     9     0      26       78    -7.0  -56.0     -77.0     -77.0 FD
 6.1    25   0-3000  13-17     75   -11.3  -60.3     -81.3     -92.8 *
 7.1    11   0-3000  13-15   67-68  -20.0  -69.0     -90.0     -90.0 FD
 8.1    22     0     17-20     76   -10.0  -59.0     -80.0     -91.5 *
10.1    31     0      25       78    -7.0  -56.0     -77.0     -88.5
13.1    13     0      28       79   >-4.0 >-53.0    >-74.0    >-74.0 FD
15.1    16     0      25       79   >-4.0 >-53.0    >-74.0    >-85.5
21.1     7     0      31       79   >-4.0 >-53.0    >-74.0    >-74.0 FD
27.1    50     0      25       79   >-4.0 >-53.0    >-74.0    >-85.5
33.1    33     0      23       78    -7.0  -56.0     -77.0     -88.5
35.1    26     0     18-19     76   -10.0  -59.0     -80.0     -91.5 *
43.1    29     0      25       79   >-4.0 >-53.0    >-74.0    >-85.5
45.1    45     0     22-23     72   -14.5  -63.5     -84.5     -96.0
49.1    46     0     25-26     78    -7.0  -56.0     -77.0     -88.5
23.1    42    NA      NA       NA              Not picked up by scan *
 * Signal from rear of antenna
 ** FD Folded Dipole for VHF, 0 dB gain; CM4221 average gain 11.5 dB 
Notice that some SNR numbers below 15 dB are given by the Sony TV.

The Sony signal strength scale doesn't go any higher than 79, no matter
how strong the signal. It's derived from the AGC, which has a much smaller control range than the dynamic range of the TV. See attachment No. 1, and notice that the calibration curve is maxed out at 79.

My newer Sony, a KDL32R400A, has a much greater range for the signal strength scale, with one dB steps. Excellent for antenna experiments, but I'm at a different location now. See attachment No. 2.

The TV did well with the real CH 20 and 45 weak signals. CH 20 is a Tropo signal that is not expected to be stable, CH 45 was very stable.

It also did well with CH 11, considering that the noise level was high on VHF-High which reduced the SNR. Some days CH 11 is stable, some days not, depending on the power line noise. A better antenna for CH 11 would improve the SNR.

See the tvfool chart in my previous post and compare the signal power (dBm) numbers at 5 ft with the OTA Signal dBm numbers in the above chart.

[rabbit73]

Originally Posted by harold

Thanks guys for all your imput. I'm going to try pointing at 333 degrees and see if I can get stations from 300 & 355 degrees.

You are welcome, Harold. Please let us know on this thread how it works out.

[rabbit73]

In post 5 I said:

It is in your favor that you are in the "wide open spaces."

The lack of vegetation can improve your chances.

To quote Calaveras:
http://www.avsforum.com/forum/25-hdt...l#post34113986

Here's a specific example I have for a station with no vegetation issues.

KACA is a low power station in the northern San Joaquin Valley with its antenna 460' above the ground. Attached is the TV Fool terrain plot showing this is a one edge path, 51 miles away and only 6.5 KW ERP towards me. There is no vegetation along the path except on the one ridge the signal passes over which is about 15 miles away. With antenna gain and system noise figure taken into account TV Fool predicts a Noise Margin of -4 dB. I should not be able to receive this station under nominal conditions. But I do receive this station and the measured noise margin is +21 dB. The SNR is almost always in the range of 24 - 28 dB. I don't know why TV Fool is under predicting this station by 25 dB but this is what I find in almost every case when there is no vegetation blocking the signal.

[harold]

I have the 8200 pointed at 285 and get the cw channel sometimes. I'm thinking with the narrow beam width I would probably be ahead to install a new multi-directional to be able to get signal from the 300 to the 355 k19aa my hd Pbs station.

[rabbit73]

I have the 8200 pointed at 285 and get the cw channel sometimes.

jdemaris had some good things to say about the 8200:
http://www.hearth.com/talk/threads/t...7/#post-851486

When I used signal projection, like from TVFool.com - I can get all the channels listed as low a minus 30 NM which is pretty weak.

The Winegard HD8200 is by far that best antenna for "fringe" reception on all the bands - low VHF, high VHF, and UHF. It's not as good on the UHF bands as several UHF only antennas but often good enough for many people. keep in mind, it's a big antenna.

jdemaris knows a lot about antennas. It is worth your time to read his post linked above and all three pages of that thread at hearth.com.

[harold]

http://www.tvfool.com/?option=com_wr...f1f0828bf958c5

I added this and used 5 for height. If I go higher I get higher NM. I'm also changing to a uhf antenna. I'll post results.

[rabbit73]

I added this and used 5 for height.

Your new tvfool report is at a different location. Did you move, or is this one more accurate?

I added this and used 5 for height.

Why? Is that the new height of your antenna?

If I go higher I get higher NM.

That is normal.

I'm also changing to a uhf antenna.

Why? Does that mean you don't need any VHF channels? What UHF antenna are you going to use?

[harold]

It is more accurate and entered many different height numbers. The 5 ft gave me -8.5 nm and. 27 ft is -11. something. The only vhf channels are 12 & 7 display channels and 8, 11 real. Twelve is PBS and available on 19 k19aa less than ten miles at 353 degrees. Seven is ABC at 123 degrees. Another Abc is available 5 k42ib at 333 degrees. The uhf antenna I intend to install is the b91x.

[harold]

If you look at the towers in my viewing area some rebroadcast the same callsign on different real channels. Example: kjtl, real 15, virt 18, 42 miles and 125 degrees. It is also k32ic, real 32, virt 18, 6 miles and 349 degrees. Again at k20jb, real 20, virt 18, 30 miles and 296 degrees. (K33hg at 225) 33 miles.
When recording some programs from k19aa instead of that programming I get recorded programming from kfdx real 28 also k25jo real 25 both are virt 3. Channel 19 is a PBS rebroadcast from kwet 74 miles and 345 degrees. K25jo has NM(db)31 and k19aa is NM(db)27
All the channels available from the tower 30 miles and 296 degrees show 14.7 – 16.9 NM(db) and with winegard 8200 antenna I have trouble picking up those. A lot of the time just a hit and miss situation.
I'm thinking if I point my antenna to 340 degrees I can pick up the tower with k19aa, also tower with k32ic, and the tower with k30jp 46 miles away. Those three towers are 333 to 353 degrees. I know the tower 46 miles show NM(db) -7 to -10. Those same channels on the tower 30 miles and 296 degrees with positive NM(db) are a sometimes available. I might still get some signal from 296 degrees with it pointed at 340?
I selected an antenna height of 5 because as I select higher the NM(db) numbers get worse until about 500.
Anyone have suggestions