I have several sand-filled HV fuses that I no longer need. If anyone is
interested, contact me off list.
George/K0IW
On Feb 16, 2010, at 11:49 PM, Fuqua, Bill L wrote:
> If I recall the fusing current for a #30 wire is about 10 amps continuous
> current.
> Eimac suggest that a #30 wire in series with the plate of a tube survives a
> discaharge the tube would not be damaged.
> This is from an application note on construction and testing of crowbar
> circuits.
>
> I have thought a #30 wire or somewhat smaller wire was stretched inside a
> grounded piece of copper
> pipe such that there would be no discharge when HV was applied would be a
> great fuse. This is because if
> an arc in the tube would vaporize the wire and producing a plasma that would
> short the B+ to
> ground via the surrounding copper tube or pipe. Also, it would be easy to
> replace.
>
> 73
> Bill wa4lav
>
> ________________________________________
> From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf Of
> K1SG@aol.com [K1SG@aol.com]
> Sent: Tuesday, February 16, 2010 6:59 PM
> To: amps@contesting.com
> Subject: [Amps] HV Fuses
>
> In recent threads, there have been a number of comments about high voltage
> fuses.
> Carl mentioned sand-filled fuses, something I hadn't heard of.
> I checked the Mouser catalog for HV fuses, and was stricken with
> sticker-shock...$38 for a fuse?
> OK, we re-think this one...
> I know that an old but workable approach is to use a thin piece of wire
> as a fuse...mount it between a couple of standoff insulators, and it should
> function fine, and if current is substantially too high, the fuse wire
> blows. How do you figure the appropriate size wire to use? And then, how do
> you
> go about ordering 6" of #30 wire, or whatever it is? If you need more
> current capacity, to use the above example, can I put two strands of #30 wire
> in parallel, and expect them to function as a reliable fuse? I'm always
> worried about kinking the wire, or if it's enameled, sanding off more than
> just the insulation.
> The plan is to fuse the HV output of a 5KV 2A supply to a 3X3, which of
> course will only be used at the legal limit or into a dummy load.
>
> Steve Gilbert
> K1SG
> K1SG@AOL.com
> 508-435-9133
> FN42fe
>
>
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