When I completely remove the preamp from the system I get a slightly higher signal on my vhf channels and slightly lower signal on the uhf channels, based on my converter box signal strength "Bad to Good Signal" scale.

At the start of my test (with the preamp in the system) I was no longer getting ABC which was disappointing, but for the most part I was getting the other major networks with a little pixelation. Without the preamp in the system I was getting slightly more pixelation.

One other thought, does it matter than I'm using galvanized EMT conduit (i.e. magnetic) as a mast? I saw that Channel Master and a few other manufactures make galvanized steel masts so I figured it wouldn't interfere with reception, but that was just an assumption.

If your current preamp is returnable, the Antennas Direct CPA-19 will have better overload resistance and a bit less noise.

You're not describing an overloaded amplifier, so I would hope for slight improvement based on the subtle improvement in amplifier noise figure. Don't expect a big change, I'm simply looking for ways to get the most from what you have to work with.

EMT is fine... it won't affect the performance of the antenna. EMT is not likely to be as strong, but the antenna is not too big, don't sweat it. Antenna mast will also be ferrous and have similar magnetic properties.

Yep, my current preamp is returnable. I just ordered an Antennas Direct CPA-19. Thanks for the advice, like you said I'm not expecting a big difference, I'm hoping for a little less pixelation.

One more question, how does wind effect reception (e.g. no impact, poor reception due to antenna movement, poor reception due to douglas fur movement)? When it was calm last evening and this morning I could pick up ABC, but during the day yesterday and today with the wind I get "no signal" for ABC.

Wind in the trees can produce changing signal levels and reflection effects. Neither is going to help the tuner do it's job.

I see that KCPQ-13 has a construction permit for a 15 KW translator on Capitol Hill, next to KZJO, KSTW & KCTS . No idea of when to expect it to come online... And at that power level, I don't expect it to be usable for you behind the hill you're facing. I still think a high-VHF antenna in the attic would easily see the primary KCPQ transmitter on Gold Mountain south of you.

I'll be quite interested to hear how the CPA-19 performs for you. A lot is going to be asked of it.;)