Once again thank everyone for the help, but above all encouragement to just try it.
I got my mast on the roof and setup the antenna, pointed it and just ran the cable from the amp loose down the side to see what I got and if I needed to change where I am pointing. (I will tidy it up at the weekend) The result was dramatically better than the backyard mount. In the back yard using a 8 ft pipe as a mast I got 5 dB on KPIX (-2.7 NM from the report). On the roof with a ~ 8 foot above the ridge line so may be 25 ft in the air I get 17 dB AND a clear picture rather than black...
but it gets better....KQED, what I wanted to get but with a -6.9 NM so tough comes in at 20 to 21 dB, a clear picture (HD) and it does not break up. KQED is on RF channel 30 and I think that is optimal for the antenna, I assume the quoted gain is somewhere in the middle...like ch 30!
So despite what everyone in Pleasanton say you can get TV, infact all the major channels from Sutro tower in glorious HD for FREE, all you need is an extreme fringe antenna and stick it as high as you can.
In summary
report is
http://www.tvfool.com/?option=com_wr...46aeeb079b5556
I used a Channel master CM 5020 Extreme Fridge Antenna with a CM 7778 amplifier on a pole ~ 8 ft above the ridge of the roof using a gable mounting kit...and a few 2x4.
I get all the major stuff I care above from Suto Tower including KQED with has a predicted noise Margin with a reference dipole of -6.9 dB but with the BIG antenna I get 20dB signal.
Once again thank you for all the help and encouragement.
I know 2 other people that were waiting for my result to cut cable, and they were both at locations that are predicted to be a little better.
Colin