[Amps] Non inductive resistor

[Will Matney]

Kanthal Globar and Ohmite makes all tupes including the tubular ceramics which most use. Both will sell direct or direct you to a stocking distrubutor. If something isn't in stock, they can order it from manufacturers stock. I'm pretty sure Allied Electronics can get or has both brands. Both Globar and Ohmite have websites with the spec sheets.

About the plastic case resistors, I seen where someone built one up with a heatsink immersed in oil. I cant vouch for how well it worked in the long run. Your best bet on this would not be oil cool it but fan cool the heatsink or use a copper heat exchanger on it and water cool it.

Rich has a neat quickie design for a water cooled one using a tubular ceramic on his website. The only thing, it isn't shielded as it used PVC pipe or I think it was PVC.

They also make some big puck type or washer looking resistors which you can stack up. I think Globar has these. You could use 5, 10 ohms to make 50 as they series themselves when you stack them on a threaded rod. Their faces are what conducts to one another. These are pretty high power and I'm not sure the cost. You can add cooling fins between each to dissapate the heat.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 4/5/05 at 9:17 PM George KB2Z wrote:

>At 10:11 PM 4/4/05 -0400, you wrote:
>
>I could use one as well. Richardson dont list  the RF Power 250W 50ohm 
>RFP250-50TC on the website. Is it from an older catalog? $10 is
>affordable. 
>The website does not have any pictures, specs, or other information
>listed. 
>Are they basically non inductive to 30MC? Can they be sunk in a gallon of 
>oil and pushed a bit?
>Mouser lists 100W Non inductive Rs that look like transistors. They are 
>supposed to be mounted on a heat sink with heat compound. Would they work 
>in a can of oil?
>Sorry if I'm asking to many questions. Thanks, George KB2Z
>
>
>Steve Thompson wrote:
> >> RFP250-50TG Flange type 50 ohms - 250W max. 3 GHz
> >> 69.00
> > For comparison, RF Power 250W 50ohm RFP250-50TC termination from
> > Richardson is $9.92 list (basically the same as RFP250-50TG but
> > different flange size).
>Sorry, typo - that should read $9.20
>
>Steve
>
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