Hi all,
I agree on the cell phone antenna BUT not all include the 800MHz band so shop carefully. This topic has been talked to death but I'll make one more mention of the old 800MHZ trunk lip mount antenna I attached to a 4" square electrical box cover, soldered 4 3" copper wire radials to and mounted outdoors on an angle bracket. I got the dinosaur for free so you may consider visiting some shops and poking around in dusty corners.
I cannot overemphasize the importance of good quality coax at this frequency! There's no point having a good signal pickup by the antenna just to dump it on the way to the receiver. Go with Belden 9913 air dielectric, best bang for the buck, but be careful since there are several similar types but only ONE is hollow. Failing that nothing less than Times Microwave LMR600 will do, LMR800 is preferable and well worth the price.
Skud, 400 is on a par with RG-8U polyfoam which is fine for VHF short runs but above 300MHz it starts to get quite lossy. 25' of it may work fine for you but still you could improve things a bit and Ginky just may have farther to go. Then he's only interested in one band so a discone isn't for him, an antenna strictly for the purpose is smaller, lighter, more durable and has decent gain while a discone has none. You've got the right idea being helpful and all but sorry, you missed the point.
Now there you go Ginky, to sum it all up what you need is not the average cell phone antenna nor scanner antenna, rather a high gain 800MHz antenna all by itself strictly for the purpose. That's why I'm using an older cell antenna ONLY for 800, not one of the new tri-band ones. I got it for nothing but if unavailable I still would have paid for an antenna strictly for the band, this is an area where no compromise is acceptable. Being 800MHz can be problematical, when it comes to antennas and coax go for the gold, you'll be glad you did. Hey, buy it at dealer net and write it off as a business expense, it pays to have a tax number.