On Jun 24, 1:03*am, Paul Keinanen wrote:
On Tue, 23 Jun 2009 13:44:24 -0700 (PDT), raypsi
wrote:

I would steal a page from the japanesse, they came out with the best
regulators by swamping components down.

In this case they would swamp the inductor with a power resistor. I've
never seen this tech used by anybody else, except in the orient.

So to gain the extra current all you have to do is parallel a resistor
across the choke.

Even resistors will regulate, smart darn japanesse.

So all the resistor has to do is soak up the other 250ma with a power
rating that it can handle the current and voltage.

You could even make it adjustable slider type so it could be tweaked.

In the OP's case, the swamping resistor would have to about twice the
DC resistance of the choke to get about 2:1 current share between the
choke and the resistor. These resistances are typically in the order
of a few ohms.

Looking at the ripple frequencies 100/120 Hz and their harmonics, the
inductive reactance for 5 H is in the order of kilo-ohms. A swamping
resistor of a few ohms would be practically a short circuit across the
choke.

Paul OH3LWR

Hey OM:

Now for the rest of the story: use a high voltage FET 2Amp at 800V
across the choke and regulate it with a LM431, programmable Zener.
I has a EICO Triband HF rig model 753, it's power supply uses 2
chokes, I regulate the outputs: 790 Volts to the final and 275 Volts
to the rest of the rig. Solid as a brick outhouse. The chokes take
most of the load off the FET's. So if the chokes saturate the FET's
take over. With all the mods I done to the EICO 753's regulating the
DC outputs is best.

73 OM

de n8zu