The later season. The antenna and knobs are all in the wrong position. So I do not think it is the MTX838.
However there is the possibility that he just grabbed a random radio from another character. Or the prop guys messed up. Etc.
The only way you'll know for sure is to actually look through episodes and check out the radios. That takes more time than I am frankly willing to spend. The later-season picture is from season 5 episode 9, if I remember the tag right. You could start there. Since most of the time a radio will be gripped in the hand, you'll probably want to keep your eye on the antenna/knob layout mostly.