SB-610 Experience

[Mark Graalman WB8JKR]

  But that fuse won't be able to supply the LV and filament currents
at the same time. That primary winding is supplying everything!


Mark  WB8JKR


On Fri, 1 Aug 2003 08:43:54 -0700 Kinney John-r17512
<J.Kinney at MOTOROLA.COM> writes:
> How about putting the fuse on the primary side of the transformer?
> All you need to know is the step up or down ratio, i.e. 120VAC to
> 600VAC is 5 times.  Ohms law says the power is the same on both
> sides (give or take a little), so if you are using 10 mA on the
> output at 600VAC then you are using 50 mA on the input at 120VAC.
>
> I have in the past used an LED for a fuse.  In the AC circuit I used
> a Bi-Colored LED (two LEDs in parallel with opposite polarity) that
> had a maximum current capacity of 30 mA.  This worked very well for
> trouble shooting also as the intensity would change with current
> changes.  Certain light bulbs would work equally well, as someone
> else on this list has already mentioned.
>
> 73's
> John KA7CVJ
>
> -----Original Message-----
> From: Mark Graalman WB8JKR [mailto:wb8jkr at JUNO.COM]
> Sent: Thursday, July 31, 2003 2:02 PM
> To: HEATH at LISTSERV.TEMPE.GOV
> Subject: Re: SB-610 Experience
>
>
>   I'm not sure but I would think the HV secondary may only
> be rated at about 10 ma. or so and the smallest fuse I've
> seen is about 100 ma. Anybody know what the secondary
> can really tolerate current wise?
>
> Mark  WB8JKR
>
>
> On Thu, 31 Jul 2003 12:06:59 -0400 Peter A Markavage
> <pmarkavage at JUNO.COM> writes:
> > Has anyone considered a small low current fuse or a fusible link
> in
> > series with one of the secondary high voltage leads. Given that
> > exact
> > replacement power transformers are not readily available and since
> > the
> > high voltage secondary winding can be under a lot of stress, due
> to
> > component aging or leaky or possible shorting of the .15 mfd
> > capacitors,
> > some means should be provided to protect the HV secondary. I seem
> to
> > recall running across computer monitors and some small portable
> TV's
> > that
> > used fuse links to protect their HV secondaries.
> > Pete, WA2CWA
> >
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