Balsam Bill

I am not allowed to post my TV Fool report url so these are my Lat and lon and height for TV Fool: lat: 46.77895 Lon: -93.15937 Antenna height 32 to 34 feet above grade.

A recomendation for the above referenced tvfool location will be greatly appreciated. I am receiving all the Duluth stations with my old setup, the signal strength varies from weak for KDLH to very good for KQDS. I have a weather beaten combination antenna of unknown make and age mounted on a chimney supported mast about 32-34 feet above grade. Coax of unknown type probably 6. An amp that is in the house not on the antenna. An RCA converter box and a 4 year old Advent HD ready TV. The signal strength is not solid on the KDLH real 33 channel and is mostly unwatchable. WDIO real 10 and WDSE real 8 are fairly steady but will pixalate and freeze and loose signal strength with , I assume, different weather conditions. KBJR has been fairly steady, but not great, and KQDS rock solid. The converter box just has a bar graph from bad to good no % numbers.This Duluth markets station transmitter choices are strange. The highest rated network CBS station KDLH bought the lowest power transmitter and the highest UHF channel 33 while the Fox KQDS stepped up to the plate and bought a 1000 watter to the party. As you can see I am 49.4 miles away and all towers are on the same compass heading which is where my antenna is pointed. Although I am located in the wooded boonies my antenna faces a cleared field and the trees are 800 feet away. Strong wind potential and snow and ice issues at times. So antenna ? preamp? better conveter? I want the best possible solution for solid watchable signals the vast majority of the time and due to the 14 pitch roof I would like to do it once and have it last. Thanks for any help.