Radiodan W7RF wrote:
>
>Do your thoughts on the negative lead or positive lead glitch resistor also
>hold true for DC choke (choke input ps)?
>+ or - OK, but with a greater need for insulation when placed in the
>negative lead?
>
I believe so... a choke input supply still needs a glitch resistor, to
handle the current surge out of the smoothing capacitor. If the choke
and resistor are in the negative side, the choke would connect to the
junction of the glitch resistor and the negative end of the capacitor.
That point will spike towards several kV negative if there is a
"crowbar" short from B+ to chassis, and if that point arcs to chassis
the surge current will bypass the glitch resistor.
Once again, it implies that the choke would need to be insulated to
broadly the same standards as if it were in the B+ lead. The difference
would be that in the positive lead the voltage stress to chassis is
present all the time, while in the negative lead it only happens in rare
emergencies.
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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