There were a few questions about current drain posted to the net. This is
a favorite topic of mine, since low current battery operation is one of my
eternal design goals :)
As a general rule, no-IF-amp receivers based on the NE602 draw around 15 to
20mA. You can reduce this further if necessary by using a
low-quiescent-current regulator for the regulated voltage (usually 5 to
8V). Also note that most AF amp chips we use in these designs operate
class AB; the current they draw varies with the load impedance and power
output. Thus if you switch to a speaker and crank up the volume, you can
see 50 to 100mA on peaks.
In the case of the NorCal 40A, the receive-mode current drain is around
17mA, and add a few more mA if you build in a KC1 keyer/counter. The
transmitter is also extremely efficient, with a current drain of only 250mA
average at 2W output running from 12V. Typical final amplifier efficiency
is 70 to 80%.
For the Sierra, the receive-mode current drain is 30mA without a KC2, and
about 35mA with. This should be of interest to backpackers (or those
running on batteries at home) who need a multi-band rig. Other multi-band
rigs are much higher. Selected examples:
HW8 90mA
QRP+ 200mA
OHR400 300mA
Scout 600mA
These rigs also have much higher transmit-mode current drain than the
Sierra, partly due to their higher output power. (The Sierra is *supposed*
to be a 2 to 3W rig when operated from batteries--it's a good compromise
for backpacking!)
Of course, the OHR400 and Scout are not likely to be carried in a pack due
to their weight. And of course the OHR400 is a great multiband kit for
home use, with very solid construction.
73,
Wayne
N6KR
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