[Elecraft] OT: heat sinking resistors

[Geoffrey Mackenzie-Kennedy]

Vic,

I would suggest that you do not clamp each resistor between a couple of 
pieces of aluminum, because some types of uncapsulated thick film power 
resistors are quite fragile. They may not appear to break if stressed, but 
there is the risk of creating a hairline fracture across the resistor 
"element".

For the two power attenuators that I use in my Rx IMD test setup before the 
combiner (precision attenuators not required in this part) I used 20 watt 
thick film power resistors in TO-220 packages, with their individual 
heatsinks sitting upright, well separated from any grounded metalwork.

73,
Geoff
GM4ESD


Vic Rosenthal wrote on Friday, May 21, 2010 at 9:27 PM:

> I just received a few Ohmite thick film power resistors for an attenuator 
> I'm making,
> rated 20 watts. They are 15mm x 10mm x 3mm. Obviously they have to be 
> heat-sunk
> (heat-sinked?) if they are going to dissipate that much power.
>
> How do you do this? There's no hole in the middle...I can just clamp them 
> between a couple
> of pieces of aluminum, but is there a right way to accomplish this?
> -- 
> Vic