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Old 20-Jul-2012, 10:18 PM   #21
GroundUrMast
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Quote:
Originally Posted by MetHerb View Post
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I'm curious why you say "actually be able to watch WPRI". The TV Fool report list the db at 4.1 and regularly can get stations now the -4 range and as low as -14. My new setup should have an antenna with higher gain (actually, I don't even have a VHF antenna now) and shorter and better cabling for less signal loss. Do VHF signals work differently? My only distant VHF station that I'm hoping to pickup is WRGB from Albany which is listed at 1.5.
...
You've got at least two TV Fool reports posted, so it's not clear which one is most representative of your situation.

Using the NM value of 4.1 dB for WPRI I get an estimated net NM of just under 10 dB at the TV, see attachment.

WRGB on real channel 6 is lower in level (using your NM value of 1.5 dB) and there will quite likely be more RF noise and interference to contend with at that frequency range. Finally, neither the 91XG or Y10713 are designed to receive real channels 2 through 6. Using a Winegard HD5030 to estimate the results I get an estimated net NM of -6.5 dB, see attached.

A net NM of less than 0 dB strongly suggests that you can't expect the tuner to lock on the signal. IMO, a net NM of 10 dB or greater is a reasonable goal when designing for 'reliable' reception.
Attached Images
File Type: png MetHerb WPRI Net NM Estimate.png (47.8 KB, 460 views)
File Type: png MetHerb WRGB Net NM Estimate.png (47.9 KB, 483 views)

Last edited by GroundUrMast; 20-Jul-2012 at 10:25 PM. Reason: target NM values
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Old 20-Jul-2012, 10:44 PM   #22
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Also, I wanted to ask about a low noise spliter/combiner. What does everyone recommend? I have a couple of ideas but I'm just wondering.
Splitters are passive components. They don't produce noise beyond the low level thermal noise. http://en.wikipedia.org/wiki/Johnson...3Nyquist_noise

The gain of the preamp is going to elevate the signals well above the noise of any passive component.

Ideal brand splitters from Home Depot have served me well. Others recommend Holland brand.

A splitter with 5 to 1000 MHz of bandwidth and 3.5 dB (2-way), 7 dB (4-way), 10 dB (8-way) insertion loss is representative of the specification ideal for OTA use.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Last edited by GroundUrMast; 20-Jul-2012 at 10:46 PM.
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Old 21-Jul-2012, 12:16 AM   #23
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In the first post of this thread, you expressed a desire to receive WSBK. Are you willing to custom build a very large antenna dedicated to that task? http://forum.tvfool.com/showpost.php...40&postcount=3

Realistically, signals that weak and subject to co-channel and adjacent channel interference are unlikely to be reliable. But some folks have fun chasing after them anyway.
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Old 21-Jul-2012, 2:11 AM   #24
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Originally Posted by MetHerb View Post
I like the fact that the Antennacraft is actually cheaper...thanks for the tip!



I'm curious why you say "actually be able to watch WPRI". The TV Fool report list the db at 4.1 and regularly can get stations now the -4 range and as low as -14. My new setup should have an antenna with higher gain (actually, I don't even have a VHF antenna now) and shorter and better cabling for less signal loss. Do VHF signals work differently? My only distant VHF station that I'm hoping to pickup is WRGB from Albany which is listed at 1.5.

Also, I wanted to ask about a low noise spliter/combiner. What does everyone recommend? I have a couple of ideas but I'm just wondering.

Thanks again everyone for your thoughts as I put everything together!
If you are in Stafford Springs then you have a lot of large hills and forests between you and the tower. And I think this is a 2 edge signal. VHF signals are tougher to catch when they are weak compared to UHF signals.

In my current location I have a Ch. 7 with a NM of around 1.0 and it is also a 2 edge. I also have to receive it through several small hills and lots of trees. And I need a pre amp to even see it for a few hours during the day because I have a very large Oak tree in an adjacent yard that directly blocks the path of the signal to my antenna at its current location. But if I moved the antenna to the middle of the roof where a chimney sits, then I would be able to watch it continuously if I added a little more height than its present 22 feet above ground.

I suspect you will run into a similar problem at your location. Every bit of extra gain will count. I've tried several VHF antennas at this location and to date the best one at getting this signal is the Antennacraft HBU 55. I tried the HD Stacker, YA 1713 from Winegard, Y10-7-13 from Antennacraft and 7084p from Winegard in this very spot and NONE of this could even detect a signal on CH. 7 at any time during the day or night while I tested them out. But the HBU 55 is actually able to at least receive it during some night time hours and early morning around daylight and beyond for a couple of hours past sunrise before it fades. BTW. The HBU 55 has about .5 db more gain on Ch. 7 than the Y10-7-13 according to the Antennacraft Tech Support desk. And the UHF section on this antenna is better than expected. It actually outperforms the MXU 59 and 91XG from Antennas Direct on most of the middle range UHF signals at my location. And on the following 2 edge, weak signals, the HBU 55 is slightly weaker on Ch. 45 (NM of minus 12) and also Ch. 17 (NM of minus 8 but comes in sporadically) but stronger on Ch. 15 (NM of around 9) . Overall it gets the nod over the other two UHF only antennas.

Last edited by Billiam; 21-Jul-2012 at 2:37 AM.
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Old 21-Jul-2012, 2:16 AM   #25
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I should add. I swapped out my RG6 for RG11 (100 foot run) and even though I am using a Pre amp (8275 from Winegard) I saw a 1.5 to 2 db gain across all channels. Whoever claims you don't need both for improving the strength of a weak signal is uninformed. It worked for me. If you see some signals breaking up after you install your new antenna or antennas and believe that another db or two will stabilize the picture, then I recommend trying RG 11 in place of RG 6 cable.
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Old 21-Jul-2012, 2:55 AM   #26
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Tv Reception.

I agree with Billiam. On the issue of using RG-11 coax.

Reception situations that require squeezing more of signal strength out , 2 to 4 dB more signal. RG-11 has less loss then RG-6.

RG-11 coax is good to use.

Here are Ultra low noise amplifiers that will squeeze out a few more dB of cleaner signal.

http://www.kitztech.com

http://www.researchcomms.com/hdtv.html

Last edited by teleview; 21-Jul-2012 at 3:24 AM.
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