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Old 9-Jan-2016, 4:13 PM   #1
tomfoolery
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Pre-amp makes things worse

First, the report: http://www.tvfool.com/?option=com_wr...51341a24f41621

Second, the satellite view of the main stations:



I'm using a DB4e combined with a telescopic dipole from a portable TV (shortened to approx. real 10 and 13 length), mounted in the attic, looking through the roof (see photo). They're combined with a UVSJ. Single 100 ft run of new RG-6, with connection to a single Panasonic plasma set through a wall plate. No other connections (not even a ground block, which I should correct).

I get all the main stations at 100% or very close to it (the first 8 channels), except that ION (WPXJ real 23) is usually solid, but often unwatchable.

But recently I started getting WKBW on real 38, which is out of Buffalo, with a NM figure of only 9.9! I only get it about half the time, since the leaves are off the trees I suppose, and usually more reliably at night. I don't care about the ABC affiliate, but it also carries Laff and Escape, which I'd like to continue getting, but more reliably.

I tried using an RCA TVPRAMP1R, with separate UHF and VHF inputs (switch correctly set) and the FM trap engaged, but it made everything worse, including my strong local channels. Unplugging the wall wart made it worse still, so presumably the amp is doing something.

I know, I know, I should put the antenna outdoors, but where it is now has a clear shot to my local stations (perspective of the map makes it look like it's through the neighbor's house, but it's not), though WPXJ 23 and WKBW 38 are through the maple (but not through the line of spruces), and I don't want to put it on the roof. I'd like nothing better than to put a DB8e and h-vhf antenna on the chimney, but that's just not going to happen. And we're not staying here much longer, so there's that, too.

I just thought there was a chance an amp would help overcome 100 ft of coax and possibly improve reliability a little, but I suppose it could be putting more noise on the line than it improves signal strength. Or it's just defective, which seems to be more common with this model than I realized.

So I guess the big question is, is it worth it to try another amp for twice the price, or am I just wasting my time?
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Old 9-Jan-2016, 5:01 PM   #2
ADTech
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Amplifier overload. You do not need nor should you use an amp, either it or the tuner(s) will overload.

Your locals are strong enough to overcome hundreds of feet of coax and a couple of splitters before any amp would be called for.
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Old 9-Jan-2016, 6:51 PM   #3
tomfoolery
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Thanks. I was afraid of something like that. So it looks like antenna improvements, like outdoor location, are the order of the day.
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Old 9-Jan-2016, 6:54 PM   #4
rabbit73
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Quote:
(perspective of the map makes it look like it's through the neighbor's house, but it's not),
You have to uncheck 45 degrees under Satellite to get 90 degree view; see attachment.

I agree with ADTech, a preamp would most likely be overloaded.

Quote:
So it looks like antenna improvements, like outdoor location, are the order of the day.
You could try a different antenna location and aim in the attic to favor ION before going outside. Maybe moving it a little further north.

You could also try a little attenuation in the coax to eliminate possible tuner overload even without a preamp which would affect ION first because it is the weakest desired signal.

There is also the possibility of interference from strong local FM signals. Try a HLSJ (high and common ports) in the coax.
http://www.fmfool.com/modeling/tmp/8...4/Radar-FM.png
Quote:
No other connections (not even a ground block, which I should correct).
The NEC doesn't require that the coax be grounded with a grounding block that is connected to the house electrical system ground for an attic antenna, but it is a good idea for your personal electrical safety and to reduce the chance of interference.
Attached Images
File Type: jpg tomfooleryTVFmap2.jpg (188.9 KB, 221 views)
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Last edited by rabbit73; 9-Jan-2016 at 7:33 PM.
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Old 11-Jan-2016, 12:21 PM   #5
tomfoolery
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Thanks. I'll try moving it higher and a bit north and see what happens.

The image now has '45 deg' turned off (I never knew that switch even existed), and you can see that the strong local stations skim over the neighbor's roof, but it's actually well below the antenna, even with the pin moved north as it is in this shot. And the weak stations at 250 mag. clear the deciduous tree less than 100 ft away, though there are trees further away.

Ideally, the DB4e with h-vhf kit mounted to a tripod on the roof along the same line would probably be a big help, but that's not going to happen. It's not an HOA thing - it's a WAF thing, and the Telecommunications Act of 1996 doesn't cover that. And we're not staying here much longer anyway, so I'll leave the attic installation of TV and FM antennas for the new owner as a selling point.

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Old 13-Jan-2016, 9:49 PM   #6
tomfoolery
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Update: I moved the DB4e and single dipole antennas further north inside the attic, and a foot or so higher, and picked up two more channels out of Buffalo so I now get all three in the red band (WGRZ real 33, WIVB real 39, and WKBW real 38), and WGRZ shows 0.5 dB NM at 62 miles with 2-edge diffraction. From inside the attic. Yikes. Signal strength* is down to 40% on WIVB, but it's solid most of the time.

ION WPXJ real 23 now comes in 100% signal strength almost all the time (but clean all of the time), and I gained a couple more, closer stations, that never registered before. I may play around some more, as I expect the trees to interfere more come warm weather, but I'm pleased so far.

I wonder if I can sister another DB4e to make essentially a DB8e, which also allows me to take one with me when I move?

Either way, thanks for the input. I had played with location a bit, but never moved it to that end of the attic, which seemed to be the ticket here.

*I suspect the signal strength 'meter' on the screen really is strength, as I sometimes get pixelation with signals in the high 80's or better, and a clean signal with some stations as low as the 50's and even 40's.
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Old 14-Jan-2016, 2:22 PM   #7
rabbit73
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Glad to hear that my advice helped you to improve your reception.
Quote:
I wonder if I can sister another DB4e to make essentially a DB8e, which also allows me to take one with me when I move?
Maybe a good idea, maybe not. It would depend upon what your tvfool report looks like there; every location is unique.
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Last edited by rabbit73; 14-Jan-2016 at 2:25 PM.
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