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Switching Regulator Tests
Figure 23. Power Output Connection Details (Load resistor not shown)
Check for 3.1 to 3.3v across the 3.3v output. This will be going to 2.9v regulators that need at least
3.0v to regulate
Check for ~7 to 8v across the 5v output. This is output is very poorly regulated and can go up to 10v.
It will drop to 5.5 to 6v when used on transmit. This can be temporarily tested with a 150 ohm resistor.
The drain on the 9v battery should be well under 25 ma.
If the 9v test goes well, connect to 12v and check the current drain for roughly 13 ma.
At this time, remove the
The 100 ohm resistor, diode and 9v battery are not used in the final kit.
9v battery connection.
The diode can be left in place, unused, and the 100 ohm resistor will be
removed at a later time, after the main circuit board has been populated with enough parts to draw
enough current to keep the switching regulator's 3.3v and 5v outputs working properly.
It might be just me, despite the large number of parts (and active components) in the rig, the fact that the
load of the receiver can be roughly approximated as a 100 ohm resistor across a 3.3v supply is kind of
neat. This is not much more current that it takes to light up a LED to full brightness from a pair of AA
batteries. The completed receiver draws about 28 ma from the 3.3v output of the switching supply.
I might also note that after the switching supply is turned on, the current drain will gradually decrease
over time, over perhaps a hour's time. This seems to be a function of the electrolyte on the 100 uf caps
setting up and stabilizing over time.
Norcal NC2030 v5
12-18-05
Page 29 of 128
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