My wife would probably murder me at the thought.
Can't have that going on now!
I'll see what I can put together for you but first, some questions.
How high could you place this antenna and do you think the antenna itself will be above the surroundings like other homes and what not around you? If you can't get it up there, I doubt it will help much.
What system or systems would you use it for and can you hear anything at all now on the CC for those systems?
Basically if you have no signal at all now, a Yagi is not going to help much if at all. You need to have some signal to work with.
A good test is if you have a portable or one you can borrow and get up on your roof and see if it will pickup the signal you are after. Even a faint signal. If so, then a Yagi can make a huge difference. Also take a visual look in the direction you would need to aim the thing and see what may be blocking its path from the roof point of view.
You don't need a digital scanner for the test, just any portable that will accept the frequencies for the system you are after so you can actually hear the signal with you ears! If you still get nothing at all then I'd say you are SOL unless you wanted to invest in a tall tower or figure out a way to get this Yagi maybe 30 feet above your roofline. Of course you need to make sure there are no restrictions on this if your are in a HOA area with antenna restrictions.
Or will you be using it to try and improve a system that you are currently getting now.
I forget if you said what you are using for an antenna now.
When I first started thinking about a yagi, I did go on the roof and was surprised at how well I could hear the cities new P25 system. I then new right away that a yagi was going to be ordered!
I did put mine on a rotor as I also wanted to monitor St. Charles which for me is 180 degrees out from the STL system. That actually worked out some as a yagi also receives some signal from the backside. In my case, I was lucky and could hear most of what I wanted from St. Charles area while the yagi was aimed into the STL city. Some of the weaker systems out in St. Charles do require me to aim it that direction and then I lose the STL system.
So a rotor is something to think about also if you will use it for more than one system.
If it will be used for the new JEFFCO system,I'd wait for that to come online and see what kind of signal you get.
What is your current antenna now. If you are just using an indoor antenna, you may like a nice omni mounted on your roof much better than a yagi as you will not need to worry with aiming the thing as you switch systems. Plus the omni would be all band so one antenna for all.
Still use LMR400 coax though as you want as much signal as you can get at the 400 and higher ranges.
It does suck you are in a hole. I looked at a place once that was a very nice home but it was way down in a hole and only had an opening to the west where there were no systems worth monitoring. That was a shame as I loved the home but I was not going to give up my radio hobby.
It was so low that even a 100' tower would not have helped. The place basically sat right at the point that all the hills dropped down together from three sides. I called these hills mountains!
Some people said I was nuts for not buying the place but why would I want a place where I could not enjoy my number one hobby. I would have been very miserable there! It would be about the same as taking a job that you absolutely hate!
I have a funeral to attend today so I'll see what I can put together later this evening based on whatever info you can answer.
You can also send me a PM if you have anything you don't want blasted out all across the internet!
It's good to know you have tinkered with your radios before! Most would never dream of opening them up! I also have the old pro-2004 and 2006. Great old classics there and they still kick butt to this day. I use one mainly for rail monitoring and the other just sits mostly but is hooked up and ready to go. I'd say I use it more for military air band more than anything when I get into that. I switch around a lot. I can go for months monitoring just police and then something gets me and the next thing I know, I'm doing rail or maring or air band stuff. I do also have a bunch of old crystal scanners hooked up and running when I hear sirens.
One has all the state patrol low band crystals in it and then another is the central county fire for when I hear the sirens. I also have Chesterfield PD in both. This makes it very simple when the wife calls me at work wondering what all the sirens are. I tell her what knob to turn and she is good to go. If more than a single knob is needed though, I may as well forget about as she becomes so frustrated that I cannot get a word in sideways! So I setup the old crystal scanner with the fire just for her.