>
>Anytime I see power problems like this, I break out the scope & look for
>oscillations on the voltage output. I once had a linear power supply that
>broke into oscillation at ~55 kHz, causing TX spurs + & - same. Before it
>caused the controller problems, it crowbared itself. The problem was a
>cold solder joint on a 1000 uF output filter cap.
>
>Bob NO6B
VBG. ESR comes in many forms.
I once had a simple 7805 that was about a 2W transmitter in the AM band.
The cap on the output had failed open circuit. The only outward
symptom was that it was significantly warmer than it should have
been, given the input and load conditions.
Linears are definitely inefficient, and can be noisier than
switchers, depending on what's going on around them.
The myth of the quiet linear is a dangerous one.
I greatly prefer switchers, but designing them is one of the things I
do for a living.
I've seen some ghastly implementations there as well. It is easier
to do a bad SMPS design, than it is to do a bad linear design.
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