91xg help for 92081

[sdchris]

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d9fbeccc886cbb4

I have a 91XG located above my chimey which connects to a uhf/vhf input (VHF is a C5) and then down to a generic amp from frys, not a channel master 7777 which everyone raves about. My problem is that I'm picking up the Fox affiliate KSWB, but I'm missing: KUSI, KPBS, and KNSD. These 3 stations come from the last location. Should I be concerned about anything that wouldn't bring these last stations in? They are the same exact distance from KSWB (fox).

I should add some more info while I'm having this beer. The vhf/uhf input is some sort of generic splitter that comes with the c5. So on my antenna mast I have the 91xg mounted about the c5. Both antennas connect to this splitter and then feed down into my channel master 3412 amp located about 25ft away. Then from there, the cable goes a few feet to my tv. I'm not sure if this would pose a problem or not. I'm assuming a 7777 mounted outside near the antennas might take care of my problem, but I'm unsure at the moment. Thoughts?

Thanks for any assistance!

Chris

[ProjectSHO89]

Several things:

The U/V combiner included with the C5 is a pretty good unit. I've bench tested several and it's a pretty efficient device for its type.

The C5 and 91XG should be 1) Several feet apart (3-4' suggested) and 2) pointed in slightly different directions (by about 30 degrees). The C5 is easy to aim (wide beam width) but the 91XG usually requires a fine touch, especially when in a low-signal environment. Being off by only a couple of degrees in aim can make or break reception.

As you are in very hilly country, there are additional considerations that won't reflect in your TVfool plot. For example, if your home is on the back side of a hill that faces north, TVfool will be over-optimistic about forecasted signal powers. Likewise, the calculations cannot take into account local obstacles such as trees, buildings and that last hill, if any. My rule of thumb is that, if you have to look upward to see the horizon from the antenna mounting point, then the antenna will also need to be tilted. Use the adjustable tilt bracket on the 91XG to boresite the boom at or just above the horizon in the aiming direction.

A mast-mounted preamp would be preferred to using a downstream distribution amp. Generally, a pre-amp is more sensitive (lower noise figure) than a distribution amp. Additionally, there is a certain amount of signal loss in that downlead before the DA. 25' of RG6 plus the noise figure differential between a PA and a DA probably equates to an additional 3 dB of system noise and that might be enough to cause a system on the edge to fall off the cliff. Also, an amp right before the TV input is usually ineffective for improving digital reception. Usually, an amp in this position degrades overall performance unless.

Check your aiming direction and tilt, install a pre-amp at the mast-head, and remove the distribution amp down-stream unless it is needed for system distribution.

[sdchris]

Thanks, ProjectSHO89. I oriented the antennas using my girlfriends iphone 3gs compass. The C5 brings in the vhf no problem.

I'm going to head over to frys tonight and see if I can snag a pre-amp. I'll also remove the amp at the bottom. Once it's complete, I'll let you know how it goes.

Chris

[sdchris]

Okay so I got the channel master 7777 pre-amp and hooked it up outside. From there, frustration ensues.

I hooked the C5 into the 7777 vhf input, 91XG into the 7777 uhf input, and then cable to preamp power supply to the 7777. From there I fed it directly into the tv like it said. Viola, a few more UHF channels come in. VHF, however, is non-existent. Confused by this scenario I try to reorient the antennas to thee proper direction. Still no luck with VHF, but my UHF is now picking up several signals from LA. They are a bit spotty, but still being received nonetheless.

My next trick was to add the amp to the mix to see if I could strengthen the signal more. It gave me more LA stations, but I still was left without VHF 8 and 10. Confused still, I decided to junk the iphone 3gs compass and just buy a regular compass.

I got a regular compass and reoriented the antennas to the proper location. They were off a good 10 to 20 degrees. Still no VHF. Confused and baffled, I unplugged everything and put the VHF output to the amp to the tv. Bam, cbs and abc. Albeit abc was a bit spotty but cbs was sharp. Back to the 7777 and nothing.

I then went back to using the splitter that came with the c5, but it causes me to lose nbc on uhf. Could it be the 7777 I got was bad? I'm not sure why the VHF wasn't passing through the 7777. Any thoughts on what I might try next?

Thanks in advance,
Chris

[sdchris]

I'm a schmuck. Okay, so if any of you are running a search on 7777 channelmaster and not being able to get vhf and uhf, this is what you need to do. Open the thing up and click the separate inputs button. Then you can use it with two different inputs.

[tigerbangs]

Don't be so hard on yourself, Chris: but if you had looked at the instructional video posted on this forum about the Titan 7777, your questions would have been answered...