The TOI adjustment is performed from 100 MHz to 3.6 GHz.
This adjustment requires a high mixer level in order to raise the distortion products out for the noise floor. In order to meet these high power levels, it is recommended that an E8257D with Option 1EA or 1EU be used. The adjustment does allow other sources (E8267D for instance) to be used. Most sources will likely achieve the required output power. However, there is a chance the output power may reach an "unlevel" state. If the source does "unlevel", then a different source must be used.