Campbell Scientific RF401-series and RF430-series Spread Spectrum Data Radios/Modems - Manual (Page 5)

– CAUTION –
Where an AC adapter is used, CSI recommends
Item # 15966.
Any other AC adapter used must have a DC output not
exceeding 16.5 Volts measured without a load to avoid
damage to the RF401/RF430 Series radio!
Over-voltage damage is not covered by factory warranty!
(See Section 4.2, Power Supplies, for AC adapter requirements)
Power plug polarity