[hpsdr] Go linear!

[Chris Albertson]

> So I vote linear.  IMHO, it's cheap, dirt simple, and quiet.  A
> little
> heavier, maybe, and perhaps a tiny bit bulkier, but it's much cheaper
> and
> cleaner.   Remember that we are in an environment where quiet is
> paramount.

I thin you are right, Just get an78XX and be done with it.  But there
are
some things switching mode power supplies do well.  One is rejecting
nois in the AC line.  

How many people remember having computers before the PC era?  Back
then, most computers used linear supplies and there was much concern
about
having your AC power be very clean.  Back then, an office copy machine
could
not be plugged into the same circuit as a computer because of all the
transients it would put on the AC line.  

Maybe for a radio we don't care if a spike comes through so long as it
in infrequent, like say when your refrigerator or air conditioning
system 
cycles.  I doubt you would notice a one time transient but computers
are different.  A one time spike that resets it every couple hours is
unacceptable.   I remember having a motor-generator installed at
a data center.

The other good thing about switching is they are "more green".  They
use
only 1/2 the power of the linear.  The linear supply converts a lot of
what comes into it into heat.  But then radios don't use much power,
only when you key the transmitter and that does not add up to much
time.

All that said this a small amount of power.  A linear supply feed from
a
pair of lead acid batteries would provide some very clean power. 
Charge
then with a switching mode charger when you are off the air.


Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Office: 310-336-5189  Christopher.J.Albertson at aero.org


       
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