On Nov 1, 2005, at 6:22 AM, Steve Thompson wrote:
>
>
> R.Measures wrote:
>> On Oct 31, 2005, at 2:04 PM, Steve Katz wrote:
>>
>>
>>> BWH is a molded wirewound device. Pretty good writeup here:
>>>
>>> http://n8sfc.com/bwh.html
>>>
>>> For high surge applications, you don't want conventional film
>>> resistors;
>>> they fail under normal conditions.
>>
>>
>> The MOF resistors we use in our suppressor retrofit kits are rated by
>> Matsushita at 100-ohms, 3W, 70ºC. In free air, they will dissipate
>> 12W
>> for one hour with a resistance change of less than 10%. At 12W, they
>> glow red in a darkened room.
> But that's only 35V across them. Many metal film resistors are a spiral
> on the form, and the gaps might arc if hv beyond the rating is applied.
Good point, but the typical potential in suppressor service is only a
few tens of volts and there are < two turns of MOF.
>
> I'm with you all the way on their capacity to withstand overload. I
> used
> to like the Dow FP2 and FP3 - you could run them until you couldn't see
> the colour codes any more, but they would still be within a few %.
>
> Steve
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|