>> I have an amp that I have put several 5.6Volt @ 5watt zeners
>> in series for cathode bias. They get way too hot with
>> about 800ma of current. Can I parallel zeners to divide the
>> current without problems with balance between them?
>
>Hi Doug,
>
>You should have enough headroom. That's only .8^2 * 5.6= 3.6 watts
>per diode.
Does P equal I^2*R, Tom? I thought P equals E*I = 4.48w.
>Maybe the heatsink is too small, or mounting is incorrect.
>
5W zeners are in DO5 packages, which are like axial-lead 3A rectifiers,
which don't use a heat sink.
>You know diodes can run pretty hot and remain safe.
Zener case temp is 25ºC/77ºF-max at rated dissipation.
>
>You could try to parallel another totally separate series string. ESR
>probably would be high enough that you may not need to equalize the
>strings with external resistors You'd have to test that, and make
>sure the strings were substantially equal in voltage.
>
>I'd probably just use a couple power transistors as a wrap around
>device to boost current, unless you wanted to use a diode reference
>and build a two- or three-transistor adjustable regulator.73, Tom
>W8JI
>W8JI@contesting.com
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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