eHam Forums => Station Building => Topic started by: WB2THV on December 13, 2004, 05:14:48 AM

Title: Linear OR Switching Power Supply??
Post by: WB2THV on December 13, 2004, 05:14:48 AM
Just a quick question.

What would be better for a "shack"? A linear or switching power supply?

I was thinking of an Astron 70A so I can power a HF rig along with a 2/440 rig, vhf/uhf amp (around 150W).

I see that switching supplies are cheaper and I don't see the higher amp versions. Only enough for say a HF rig or a mobile rig in the house.

Which one creates more "noise"?



Title: Linear OR Switching Power Supply??
Post by: WB2WIK on December 13, 2004, 09:25:38 AM
"Noise?"  If you mean radiated or conducted wideband emissions that can be heard in sensitive ham receivers, switch mode power supplies are guaranteed more likely to generate such interfering noise than linear power supplies.  However, some of the popular "ham radio" switching power supplies are very quiet, as they've been designed and manufactured to minimize this problem, with the knowledge that the power supply *will* be connected to ham gear.

The power supplies sold by the major manufacturers as accessories to their equipment (Icom, Kenwood, Yaesu) are switching type power supplies, almost without exception nowadays.  The reasons are long and varied, but in general, a switch mode power supply is not only lighter, but can also cost less to manufacture and be designed as "universal input," so a single power supply model can be used all over the world without changing anything except the plug on the end of the cord.  You can't make a "linear" supply like that cost-effectively.

The Astron RS-70M is a good, solid linear supply.  I've had one in my shack for many, many years and absolutely never shut it off.  Last time it was "off" was when I moved, over four years ago.  Likely next time it will be "off" is when I move again, unless there's a utility power failure in the meantime.


Title: Linear OR Switching Power Supply??
Post by: NS6Y_ on March 19, 2005, 10:21:10 PM
You can't go wrong with a linear.

Some switchers are considered very quiet, and some people seem to be very happy with them - if you go with a switcher I'd recommend a new one made specifically for ham radio by a reputable manufacturer.

An RS70M has got to be one HEAVY mutha, make sure you need one that big before running out and buying one, you may only need an RS35M or an RS12M.

With Astrons the number in the middle like 12 etc is the number of amps, and the M means it has Meters, which cost a little more but are often well worth it.