Campbell RF401, Instruction Manual, Page: 30 / 130

RF401-series and RF430-series Spread Spectrum Radio/Modems
14
TABLE 4-1. 15966’s Voltage Regulation
Current Drain
(mA)
Resistive Load
(Ohms)
AC Adapter Output
(Volts)
0 (no load)
∞
(open circuit)
12.22
122
100
Ω
12.20
807
15
Ω
12.11
The voltage regulation of the 15966 is exceptionally good.
Power connector polarity: inner conductor positive (+)
There are many AC adapters available with barrel
connectors (plugs) that will fit the RF401 or RF430. Some
of these (including the CSI AC adapter Item # 272) will
cause immediate damage if plugged into the RF401 or
RF430 even briefly. It is also possible to damage the RF401
or RF430 with an AC adapter labeled as low as “12 VDC”
because it may output an open-circuit (no current drain)
voltage exceeding the maximum. The very low quiescent
current (170 µA) of the RF401 or RF430 in its default and
other standby modes allows the supply voltage to rise at
times virtually to its open-circuit level.
The RF401 or RF430 radio will sustain
damage if the Power jack voltage ever
exceeds 18 Volts!
120 VAC line voltages vary from location to location and
from time to time so observing a 16.5 VDC maximum is
wise. Unconsidered AC adapter selection raises the specter
of over-voltage damage to the RF401 and non-warranty
repairs!
There are several things to consider. Beware of AC
adapters outputting an AC voltage. An AC adapter can
output the correct voltage but the wrong polarity. The center
conductor of the barrel connector must be positive (+). The
AC adapter must also be capable of supplying the
instantaneous peak currents demanded by the RF401
transmitter. The best approach is to obtain the AC adapter
recommended by CSI (Item #15966). If this is not possible,
obtain an AC adapter that matches the voltage vs. current
characteristics shown below.
To be sure that the candidate AC adapter’s “no load” voltage
is below the 16.5 VDC recommended maximum, measure
the output with a DC voltmeter while the AC adapter is
plugged into the outlet but not powering anything.
CAUTION