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Old 05-16-2011, 05:26 PM
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VintagePC VintagePC is offline
Tube bug got me 05/2010
 
Join Date: May 2010
Posts: 535
Quote:
Originally Posted by wa2ise View Post
That will work, but the fuse should be around 1.5amps or so. That's what I see in various B&W tube sets using a resistor and fuse. 0.041A is way too small.
I'd second this. The primary function of a fusistor is as a fuse. The secondary function (especially in tube sets) is to limit inrush current with the resistance it offers, providing a "soft-start".

The wattage for the resistor will be different (as you've discovered) because the heat dissipation of the resistor is much more efficient than that of a thin wire as in a regular fuse - so it can have a higher current without damage than its wattage implies.

If you can't get a replacement, you can do as you suggested, but for current rating, you should go 1.5-2x the current rating on the back panel of the set (if present). If you can get an actual current measurement, even better.

The reason you don't want an exact match is thermal stress- Inrush current (somewhat limited by the resistor) will be higher than normal draw, and even if it does not exceed the fuse rating, it causes the metal wire inside the fuse to flex from thermal expansion as it heats up- leading to premature failure and "blown" fuses when there's nothing wrong.
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