SECOND HAND 
HT BATTERY ELIMINATOR (APPROX 90V)
 It takes 6 AA 1.5 volt batteries and converts their 9v output to 90V dc. Output is via a din connector, but you could wire direct. The design of the unit is such that the 90V output is only generated when the unit is connected to the load, so the AA batteries do not go flat when the radio is turned off.