[AMPS] Re: PS diode equalizing

[Rich Measures]

>Rich says;
>
>>However, without equalization resistors, there is equal reverse current in
>each >diode -- provided that the diodes are similar.
>
>Not quite - they should be identical. Minor point, apparently, but mixing
>from batches is a no-no.You may well need to use diodes from adjacent sites
>on the same wafer if you are going to push to the rated voltage  limit,
>because of the requirement to get capacities equal. 

€   at 35 or so kHz, this could be important. 

> Choosing diodes for
>equal breakdown voltages can lead you astray. 'Soft' breakdowns don't
>necessarily give the full answer, because break down volts reduces with
>temperature, but they do help. 

€  So use a 50% safety factor.  1N5408s are not expensive.  

> If you're buying your diodes 'loose' you've
>really no guarantee about 'batch' matching; it's slighty better if you buy
>them bandoliered, but there's still no guarantee. I suspect that using
>under-voltage rated resistors is probably worse than using a bandolier of
>diodes and no resistors.
>
€ I agree.  



Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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