[Elecraft] OT: heat sinking resistors

[Don Wilhelm]

Phil,

Is this recent data? Has something changed?  I have had plots of the 
Caddock 50 ohm 100 watt resistors taken to 250 MHz and the return loss 
indicated that they made very good attenuators and dummy loads at that 
frequency - assuming they were mounted with zero length leads directly 
to a BNC or SO-239 connector.  My data is 2 years old.

BTW - the facts I have quoted are good only for the 50 ohm Caddock 
resistors - I have found that other values were "as stated" 
non-inductive, but they certainly were capacitive.  A capacitive dummy 
load is just as bad as an inductive load.

73,
Don W3FPR

Phil & Debbie Salas wrote:
> "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."
>
> FYI - Both Ohmite and Caddock make versions of these resistors that have screw holes for mounting.  The lower power parts (15-20 watts) are pretty good thru 2-meters.  However, the higher power versions (especially the 100-watt versions) can start to look bad at 50 MHz due to the large package capacitance-to-ground.
>
> Phil - AD5X
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>