[Amps] Has this SMPS got too much ripple for a SS bias

[Jim Thomson]

Date: Wed, 2 Oct 2013 15:10:42 +0100
From: Chris Wilson <chris at chriswilson.tv>
To: amps at contesting.com
Subject: [Amps] Has this SMPS got too much ripple for a SS bias
supply?


  02/10/2013 15:09

I have a Skanti commercial solid state 250W RF amp, 1 to 30 MHz. It
needs 50 volts and 5 volts supplied to it. The 5 volts is for the bias
circuits. I am told they draw about 3 amps maximum. I have a good
quality regulated 4 amp SMPS at 5 volts. Here is a `scope screen shot
of the ripple, measured without ground lead tails on the probe, direct
across the output to minimize pick up. The dots are the cursors, it's
an elderly Tek 7854 analogue `scope. Is this OK to use? Or do I build
a linear regulated supply? Thanks.

The `scope screen shot is at http://www.gatesgarth.com/ripple2.jpg  as
I don't know how to upload a shot here.

-- 
       Best Regards,
                   Chris Wilson.
mailto: chris at chriswilson.tv

###  IF this had no load on it, there would be No ripple at all.    The bigger the load,
the more the ripple.  Try putting a BIG lytic across the 5 vdc output.   That will kill the 
ripple asap.   You want a straight line on the scope....   5 vdc..under load.  
Right now, that scope pattern looks like a dogs breakfast...too much ripple.   

Jim  VE7RF