>
> What makes this big difference, the MFJ one does not have a transformer
> inside?
> _________________________________________________________________
>

Hi,
one of them (the 2nd) is a linear supply, while the other one (the first) is
a switching supply.
In a linear supply, excess power is dissipated (meaning it needs to be big
for heatsinking, plus a big line transformer), whereas in a switchmode
supply, the voltage conversion is very efficient, ideally 100%, so there is
no need for that much heatsinking, and there is also no need for a line
transformer.
Current limiting can be easily implemented in both cases (generally it's
done by using a sense resistor with a very small value and measuring the
voltage drop across it), but in one case I guess they chose not to.
- Marcel
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