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Old 30-May-2016, 11:09 PM   #1
eggman531916
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preamp with separate VHF/UHF isn't separating bands enough

Ok. So on Saturday I hooked up separate Vhf-Hi and a Uhf antennas for my mother using a RCA TVPRAMP1R pre-amplifier. She picked up 15 channels where before, she only had 2 channels (8.1, 8.2 on real channel 8)which is WGAL, Me-TV. The problem I'm having is that, while she picked up an extra 13 channels, both 8.1 and 8.2 are now heavily pixelated and are her worse channels. I could pick up real channel 8 no matter which way I pointed a single antenna. the problem happened when I combined the two. I'm thinking that the channel 8 signal is so strong that it's still getting through the pre-amp on the Uhf side. For Uhf, I built her a McClapp vertically stacked 8-bay with 9" spacing and 9.5" whiskers. I probably should've built a Uhf only gray-hoverman, but I really didn't expect to have the only Uhf channels come off of an almost 90 degree angle either. I was originally going to try to use the 8-bay for both bands. So, after that lengthy explanation, I was wondering what would be a good way to attenuate real channel 8 out on the Uhf side. I thought about using Vhf/Uhf diplexer before the preamp on the 8-bay and leaving the Vhf side unused. Thought anyone?
Here is the TVFool report, but I'm not sure about the accuracy of it:
http://www.tvfool.com/?option=com_wr...e2cbe9e92f7239
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Old 31-May-2016, 10:35 AM   #2
ADTech
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Channel 8 is far too weak to cause any overloading. More likely, the amp is defective or the switch isn't set properly.
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Old 31-May-2016, 11:38 AM   #3
No static at all
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I'm wondering if the TV picked up & re-mapped one of the weaker UHF translators when you re-scanned? I would try disconnecting the UHF antenna & then try rescanning to see if it sees RF 8.

Does her TV allow you to manually input channels?
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Old 31-May-2016, 7:28 PM   #4
rabbit73
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Hello, eggman:

I see you also posted your question on DHC, but I'll answer here first.
Quote:
on Saturday I hooked up separate Vhf-Hi and a Uhf antennas for my mother using a RCA TVPRAMP1R pre-amplifier.
What VHF-High antenna are you using?

The RCA preamp has a quality control problem. When the combined/separate antenna switch is in the separate position, it sometimes doesn't make good contact with the VHF antenna. The fix is to use the combined position with a UVSJ before the preamp to combine the antennas.

I agree with ADTech, overload doesn't seem likely, unless the tvfool report is waaay off. The report puts her in a valley and not on a hill top. The terrain in her area is very rough.

I did an FM report based on the short coordinates for the tv report; I don't see any strong FM signals that would interfere with TV reception.
http://www.fmfool.com/modeling/tmp/b...1/Radar-FM.png

Also using the short coordinates, I did a terrain profile that puts her location along Pine Grove Rd route 233 in the Michaux State Forest between Fayetteville and Wenksville. There are some hills in the signal path from WGAL.

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File Type: jpg eggman531916TVFp2WGAL.JPG (107.2 KB, 609 views)
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Last edited by rabbit73; 31-May-2016 at 8:36 PM.
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Old 31-May-2016, 10:10 PM   #5
rabbit73
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I did a second profile with the signal path from WGAL extended a little beyond your mom's location.


Quote:
The problem I'm having is that, while she picked up an extra 13 channels, both 8.1 and 8.2 are now heavily pixelated and are her worse channels. I could pick up real channel 8 no matter which way I pointed a single antenna. the problem happened when I combined the two. I'm thinking that the channel 8 signal is so strong that it's still getting through the pre-amp on the Uhf side.
I also suspected overload until I did your FM report and saw another hill beyond your mom's location.
Quote:
Here is the TVFool report, but I'm not sure about the accuracy of it
I am willing to do another more accurate profile to confirm my theory, if you can send me her coordinates in a PM for privacy. You can see the coordinates change below the tvfool interactive map browser as you drag and drop the cursor to her antenna location. The interactive map browser is here:
http://www.tvfool.com/index.php?opti...pper&Itemid=90

I see a lot of trees in her area; are there any in the signal path?
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File Type: jpg eggman531916TVFp2WGALext.JPG (103.5 KB, 621 views)
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Last edited by rabbit73; 31-May-2016 at 10:42 PM.
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Old 3-Jun-2016, 2:13 AM   #6
eggman531916
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Thank you all for replying. Sorry in the delay to answer, but work's been pretty hectic lately. Anyways, real channel 8 could be picked up from any direction on either antenna, no matter where I pointed it. So, I'm thinking TVfool may be way off on that one. The other Vhf-Hi channels come in perfectly, real channels 10 and 12, so I don't think it's the preamp. I'm not sure what particular make and model Vhf-Hi antenna it is, as I found it when someone was going to throw it out, so I took it home and repaired it. I believe it's a 9 or 10 element yagi, but I'd have to recount the elements this weekend to be sure. There are a lot of trees around as you guessed correctly on the location. But, again, on their old antenna, they could only pick up real channel 8. Channel 49.1 (real 30) comes in at an odd angle at almost 90 degrees to the left of WHTM, which doesn't really make sense either unless it's a reflection or something, but I did notice other people's antennas pointing in that direction too. All this is why I was guessing it may just be the antennas interfering with each other with both picking up real channel 8. Basically, my plan at this point is to use the Uhf side only of a UVSJ and put it before the preamp on the 8-bay to try and knock down the Vhf-Hi signal. No need to worry about another scan Rabbit73. You've pretty much nailed it on the first ones. Thank you though anyways.
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Old 3-Jun-2016, 2:15 AM   #7
eggman531916
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No static at all.....I had thought of that too, but not until after I left her place. I'm probably gonna try that this weekend if my first plan doesn't work.
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Old 3-Jun-2016, 2:17 AM   #8
eggman531916
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I'll let you all know what I figure out. Thanks for all the help!
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Old 6-Jun-2016, 3:45 AM   #9
eggman531916
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Success!

Alrighty then. First off, I must humbly admit that I was wrong about the antennas interfering with each other. Secondly, it turns out that while real channel 8 is a strong signal, it can still be blocked. While I don't understand why I could pick it up everywhere around her house and in every direction, it turns out that my final mounting spot needed some adjustments by first cutting a single branch that was about 10 feet directly in front of the yagi, and secondly, for whatever the reason at this spot, I actually had to aim the thing whereas before, it wasn't necessary. I tried each antenna individually first and when that didn't work, I plugged the 8-bay into the VHF port, which also didn't work. That's when I noticed the branch and cut it. Channel 8 came back in pixelated (it wasn't even doing that when I got there). I aimed it about 10-15 towards the direction of the transmitter and it cleared up perfectly. So, problem solved. And in my haste to hurry before the thunderstorm rolled in, I over tightened the balun and broke it, losing all Vhf-Hi channels. Of course, I didn't have a spare, so I stripped the coax and put the ground braid to one side and the center conductor to the other and it worked (I think I saw this in one of the other threads). Not the greatest solution, but it should hold until I can get back down there to put another balun on it. Can someone tell me why this worked and if that's the case, why use one at all? I'm going to copy and paste this for the Digital Canada forum as well.(That's alot of typing.)
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Old 6-Jun-2016, 3:18 PM   #10
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You can pick up an RCA-branded balun at almost any Lowes home center. I just picked up two a week ago at my nearby store so I can check them out.

http://www.lowes.com/pd_302829-63374...d=3724168&pl=1


FWIW, it's exactly the same balun that Winegard puts on the RCA-branded stick antennas they build for Voxx and is also exactly what you'll now get if you order a Winegard TV2900 from Solid Signal.

The direct coax connection worked because it was "good enough", the typical requirement for digital reception.
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Last edited by ADTech; 6-Jun-2016 at 3:21 PM.
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Old 6-Jun-2016, 5:02 PM   #11
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Thanks for the link AD Tech, and the explanation. It looks like her Lowe's carries it, however, mine in Altoona does not. At any rate, I appreciate all the help I've received and the wealth of information from reading through the forums. Thank you.
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