I do most of my scanning listening to 800 MHz on my SDS200 Uniden scanner. For an outside antenna which is probably better, the Tram 1410 or the Tram 1411 for listing to 800 MHz ?
So if I want my tram 1411 to work better on 800mhz / P25 , Literally cut the whip in half ?Most discone designes are for some reason optimized to the 90-100MHz band, with the lower elements having a lenght of 35 inch or longer and diameter of the horisontal elements 25 inch tip to tip. Reduce all elements to 75% to still receive max at the VHF airband. Airplanes are usually received at line of sight with any sort of antenna so that could probably also be sacrified and then use the suggested cut all lenghts to half method to still receive max at mil air frequencies. If only 400MHz and above are needed then cut down to 1/4 lenght of the original size to really optimize the 700-900MHz reception.
You can use the calculator at: VE3SQB Antenna calculators