The TVPRAMP1R is very competitive with the other preamplifiers intended for strong signal areas and it has very acceptable noise performance compared to any other consumer grade preamplifier.
Follow ADTech's suggestion re. keeping FM out. Then, if you run the basic antenna performance test and find the antenna is not providing a reliable signal on CH-7, you need to consider height/location options, adjustment/modification of the DIY antenna, addition of a H-VHF antenna or a new antenna.
Given your interest in DIY, a Yagi is easy to build:
http://forum.tvfool.com/showthread.php?t=1106 You could design/build for channel 7 and expect coverage of 9 as well. If you're familiar with 4NEC2, you may want to cross check the VK5DJ design before cutting material.