Rich Measures wrote:
>>I don't use equalizers in any new power supply, but I do take care to
>>use more and better matched diodes - so we agree on that much, Rich.
>
>Indeed, Ian. And do you measure the avalance potential of each unit?
>
No, because I don't have the capability to measure it at the actual
junction temperature it will reach when operating at full load.
Instead I buy quality parts and rely on uniformity from mass-production
- and if in doubt, use more diodes. That goes along with using mains
filters and VDRs to minimize the risks from incoming line-side spikes.
>>On the other hand, I won't tear the equalizers out of existing power
>>supplies that have proved reliable.
>>
>If you have 4x as much piv as needed, it should play ok..
Let's not overstate the risks. Hundreds of thousands of equalized diode
strings in older equipment (designed back when PIV was expensive) are
running successfully and reliably at lower PIV margins than 4x.
I would never build a new rectifier stack that way, but still think the
best strategy is to let existing ones run till they drop... if they ever
do...
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.demon.co.uk/g3sek
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