[Heath] Replacement Capacitor Needed

[Wilson Lamb]

I expect the worst spikes occur when the PS is switched off and the primary happens to be at max voltage.
Don't skimp.  A shorted cap will ruin the xfmr, if there isn't a good fuse.
WL

----- G3OOU--- via Heath <heath at puck.nether.net> wrote:
> 
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>Hi Doug
> 
>I think that you are referring to C59 across the high voltage secondary of 
> mains transformer T-1. This capacitor must have a voltage rating in excess of 
> 1.414 times the rms voltage across it plus an allowance for the mains supply to 
> rise to its maximum tolerance and then some additional contingency. The 
> 1600v rating seems very reasonable to me.
> 
>You can get high voltage ceramic capacitors and use two or three in 
> parallel to make the total capacitance required.
> 
>I assume that the original capacitor was intended to reduce spikes from the 
> mains as it is a large value and probably the wrong type of construction for 
> high frequency RF decoupling.
> 
>73

Bob
Bob F Burns G3OOU, 
> G-QRP 6907, @BobFBurns
Crystal Palace Radio & Electronics Club: www.g3oou.co.uk
Technical web site: www.qsl.net/g3oou 
> 
>
>In a message dated 25/10/2017 01:30:10 GMT Standard Time, 
> dkdavies3 at gmail.com writes:
>
>I need to replace a buffer capacitor in the power supply 
>  rectifier circuit in an old HW-10 Shawnee I'm trying to restore.  It is a 
>  paper cap, oil filled and the value is 0.047uf @1600 volts.  I can find a 
>  0.047uf one but nothing rated at 1600 volts.  Is this a critical value or 
>  can I replace it with a polypropylene one rated at 650 volts? 
>

>Doug
>VE7DRF

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