[Amps] Switching Power Supplies

[Will Matney]

See below;

*********** REPLY SEPARATOR  ***********

On 7/14/06 at 9:48 PM Tom W8JI wrote:

>> Why don't you ask these folks:
>>
>> http://www.wattsunlimited.com/
>>
>> Surely one of you have disected this thing already.  No, 
>> it's not a good supply for a "tube with handles", but it's 
>> pretty cool for what it is...
>
>
>17% no load to full load regulation isn't so hot Joe. I'm 
>not sure how that would be for IM products or CW waveform 
>since power out is generally about the square of supply 
>voltage change. The CW waveform would look funny with that 
>much sag.


The Heathkit 220 and a few other models had around 15% regulation which is right on the edge of 
saturation (they ran a high flux density to save on weight and cost). They don't saturate, but under full 
load they're cutting it pretty close. A good stiff power supplies sag will be around 11% to 13% typically. 
I always use 12% when I'm figuring the DC voltage needed from a transformer.

>
>As for faults, the problem faced by a supply near the 
>negative rail, especially one with a grounded screen, is a 
>HV to ground fault dumps crap back into the supply. Most 
>supplies are pretty good at running into shorts, but they 
>are almost always terrible about handling reverse applied 
>voltages from supplies hundreds of times higher in voltage.

It's best to switch a transformer instead of using a choke in this instance. Any HV DC coming back 
would be isolated from the switching transistors/FET's, and their drive or oscillator. If it were me, I'd
use a converter circuit for the supply.


>
>73 Tom
>
>
>
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Best,

Will