We introduce a vertical hot electron transistor structure in which the base is a two-dimensional electron gas (2DEG), upon which we can carry out both magnetoresistance and quantum Hall measurements as the transistor is turned on. Hot electrons are injected to have a controlled angle of incidence with cold electrons in a 2DEG and we examine the resulting effects on its magnetoresistance. We present new data on the various forms of electron heating that we are able to achieve in the base.