No, you want to drop it by 2 Volts. With 1 Volt, you are still 10%
high. That's way too much!
To destroy 2 Volts at 15 Amps so you need a resistance of 0.133 Ohms
in series with the filaments. The resistor will be dissipating 30
Watts. 8pcs x 1 Ohm/10W wire wound resistors in parallel gives you
0.125 Ohms (1.875V drop) and 7 in parallel gives you 0.143 Ohms
(2.145V drop) with plenty of dissipation headroom.
Alternatively you could use some lengths of smaller gauge wire in
series with the filaments to lose the 2 Volts but remember that you
are dissipating 30 Watts continuously so make sure you don't melt or
burn anything.
Once again, don't settle for 1 Volt drop.
73, Alek
VK6APK
At 03:03 AM 16/09/2009, MIKE DURKIN wrote:
>Ok.. yea i did search some on reducing the voltage at the heaters on
>google ... yikes alot of what in not really looking for.So a quick
>question .. what is the favored way to reduce the voltage ?? i have
>12V ac across 2@3-500z's and i want to drop it by -- say 1 volt.
>Trying to keep to the confines of what i have around .. some 12 and
>10Ga solid magnet wire, some romex (120v stuff) and some 12ga hookup
>wire witch i dont think the insulation is rated for heat at all ....
>Or some other common junk drawer stuff that would do the trick ...
>the last thing i tried was a .27Ohm 10W cement resistor and that was
>too high of a resistance ( was a bit surprised but oh well i dont
>know the internal resistance if the filaments anyways)
>KC7NOA ... i think i even have some nichrome sitting round some where.....
>
>
>
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