[rabbit73]

What is the longest practical lead-in run length and lowest loss transmission line?

If you don't use a preamp, the coax loss directly subtracts from the antenna gain. The attenuation factor for coax increases with frequency, so the loss for UHF channels is greater than for VHF channels. It is about 6 dB per 100 ft of RG6 for UHF TV channels.

When you use a preamp, it compensates for the transmission line loss by making the signal stronger before the loss. The preamp should be near the antenna to keep the coax loss between the antenna and the preamp input low.

Most systems can tolerate RG6 runs of up to 200 feet, depending upon the current draw of the preamp. The signal travels on the surface of the center conductor; the DC current for the preamp uses the whole cross section of the center conductor. RG6 with a copper clad steel center conductor is usually OK up to 100 feet; switch to RG6 with a solid copper center conductor up to 200 feet. RG11 and hardline are used for longer runs.

Since the preamp is at the headend of the system, it determines the system noise figure, so the distribution losses after it become less important. To increase your understanding read through this thread:

http://forum.tvfool.com/showthread.php?t=109

I don't understand what my location has to do with the best deep fringe antenna.

My house is in a depression so I am planning to put a tripod and mast atop the ridge of the gable roof.

As an example, if the signals are coming in over a ridge line, the tilt feature of the 91XG might be useful. It would allow you to tilt the front end of the antenna up to intercept the incoming signals.

but I would like to know which antennas (intended for residential installation) have the highest gain.

The Antennas Direct DB8e is the current champion for a high gain UHF antenna. The VHF section of the Winegard HD7698P is near the top of the list; it is also one of the highest gain VHF-High/UHF combo antennas.

There used to be a good selection of VHF-only antennas, but they have been discontinued. The MCM 30-2475 and 30-2476 imports have just become available. They are inexpensive, have poor assembly instructions, but perform OK.
http://www.mcmelectronics.com/produc...-2475-/30-2475
http://www.mcmelectronics.com/produc...-2476-/30-2476

Thanks for the coordinates. Your report would look like this:
http://www.tvfool.com/?option=com_wr...5134c727dda50f

It looks like you have a good selection of networks at 320 degrees magnetic. Most of your channels are UHF, but ABC and PBS are on VHF-High real channels 7 and 13. You can use a VHF-High/UHF combo antenna or use separate VHF and UHF antennas.

Sometimes strong local FM signals can interfere with TV reception. Taking a look at an FM report can influence decisions about an antenna system for TV reception. Here is your fmfool report:
tmp/7e4636a14a/Radar-FM.png
KYKC -24.1 dBm doesn't look like a serious threat, but you should have an FM filter.

If you want to protect your privacy, you can now delete your coordinates.