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Old 5-Mar-2015, 5:11 PM   #1
EndoftheRoad
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In Maryland, hoping to get Philly Stations

I've looked everywhere trying to figure out if its worth it for me to proceed or not. Figured it was time to ask the experts.

I'm on the upper chesapeake, roughly 60 miles from the Philly OTA signals that I'd like to pull in. I'd like to bring in WPVI(-94.0dbm), WCAU(-104.1),KYW(-102.5) and WTXF(-110.9) From looking at the DBM's, I'm assuming that the only shot i have is wpvi. We're at the far end of a peninsula, with a significant amount of foliage between.

http://www.tvfool.com/?option=com_wr...f1f02659bf0373

Configuration wise, I already have a Channelmaster 7777, and had an antenna that was already in place in my garage attic(forget the brand/model). Bought the CM 7777 hoping to boost the signal, and evidently the antenna that is in place is shot since i couldnt bring in any signals, and upon further inspection the antenna looks like it was attacked by a gorilla or a manbearpig.

The garage attic space is roughly 20 feet high where it would be mounted from ground level. The garage is preferable, but not my only option. I have the option of adding height to an existing pole which a cellphone booster is attached to that is about 25feet off groundlevel now if need be.

I'm more or less at the point where i just want to know if it's even worth the investment of an antenna. I've looked into the wingard HD7698 series, and Channelmaster CM3020. It's one of those i already have the preamp, do i invest more or just accept that Philly Stations are not going to happen. A cheapy monoprice antenna brings in 4 baltimore stations, so thats always a backup.

Any insight would certainly help.

Thanks,
Justin
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Old 5-Mar-2015, 5:47 PM   #2
No static at all
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My 2 cents . . . . you have a shot at WPVI if all nearby power lines are underground, but maybe 50/50 at best. The other Philly channels are too weak to be reliable.

Let's see what others have to say.
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Old 9-Mar-2015, 3:40 PM   #3
EndoftheRoad
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Closest above ground power lines are probably around a mile away I'd venture to guess if i'm looking at a straight line from the residence to the broadcast tower
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Old 9-Mar-2015, 3:50 PM   #4
ADTech
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My 2 cents: I see no real shot at reliable reception of WPVI since the real-world low-VHF noise floor is usually anywhere from 5-20 dB higher than the assumptions built into the simulator.

However, if you're going to try for it you will need something really big with wide elements at the rear. FM radio interference is likely to be an issue also, as WPVI is immediately adjacent to the bottom of the FM band and your pre-amp's FM filter is going to be ineffective at mitigating its effects due to the combination of its rejection band and your local FM frequencies in use.
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Last edited by ADTech; 9-Mar-2015 at 3:56 PM.
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Old 10-Mar-2015, 6:01 PM   #5
EndoftheRoad
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Great point about the FM interference, totally ignored that. So I guess i'll have a channel master Titan for sale. Thanks for taking the time to review.
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Old 11-Mar-2015, 1:56 PM   #6
Tower Guy
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If you want to try for WPVI anyway, here are a few thoughts.

ADTech is right, the low band noise must be subtracted from the NM value. The FCC assumes 4 db, which is a quiet rural location.
WPVI runs about 9 db more power than the TVFool database shows.
Low band is less effected by foliage than other channels, but you are so close to the limit that you need to plan to get above the trees.
Once above the trees, the NM value also increases due to height. It's + 4.6 db at 50', +10.5 db at 70'.

So, if you consider a 70' tower, the real NM with WPVI's power is +19.5 db. If you add 6 db antenna gain and subtract 4 db extra noise, the net NM is +21.5 db. That should work even in a noisy location.

The correct all channel antenna for WPVI is a HD7084P or HD8200U.

At 70', the NM values for most of the Philly stations becomes reasonable.

Strong FM stations can overload a preamp. The signal strength of the strongest FM station, WXCY-FM at 103.7, is -22.9 DB. That's a concern, but not an insurmountable problem.
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Old 13-Mar-2015, 6:21 PM   #7
stvcmty
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There are 2 analog LP channel 6s that you may have to worry about. They are both being used as Franken-FMs on 87.7. One is in DC and is Spanish (WDCN-LP), the other is on the Eastern Shore (WDCO-LP). The audio portion of their signal is surprisingly resilient and carrys stupid-far. (I am in Harford county MD, so how well they get to you may vary from my experience.)

Driving along 152 I can catch Spanish language programing on 87.7. In Bel Air I can get Christian Programing on 87.7. From me, WDCN is 56 miles and WDCO is 103 miles. That shows part of the problem of VHF-low, a low power signal can carry on forever.

They may cause co-channel noise. That could lead to non-intuitive aiming of an antenna for philly. The half power beam width of an antenna at VHF-low frequencies is pretty big. If WDCO is causing co channel interference, getting the antenna to put WDCO in a null could help, which if there is a null at 90 degrees would mean aiming the antenna at 62 degrees true rather than 45 degrees true.

WPVI is transmitting circular polarized, so it could even be worth trying skewing the antenna (antenna elements would not be parallel to the ground). There may be some skew that helps null out noise.

Your TV fool plot shows a pretty good chance of getting WMAR, ABC out of Baltimore. You might want to compare WMARs schedule to WPVIs schedule to see if there is enough philly originated content to go after. About all I can think of is the Thanksgiving parade, but that ends up on ABC out of DC.
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