[Amps] PSU design question

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Sat, 7 Nov 2009 17:20:04 +0000, Ian White GM3SEK <gm3sek at ifwtech.co.uk>
wrote:

>
>This resistor needs to be there, but it's only ever intended as a 
>backup; its value doesn't need to be a low enough to allow the HV supply 
>to deliver normal current.

REPLY:

Sorry, but I have to disagree with this design philosophy. If you are going to
add another part as a "backup", add another large diode. A 100 ohm resistor of
modest size could be blown open by a massive arc, thereby leaving the B-
floating, whereas a diode will almost certainly develop a dead short, far
greater protection. And big diodes are cheaper than big resistors anyway.

73, Bill W6WRT