Putting several in parallel on a suitable outboard heatsink is not expensive and, properly rated, will cater for any load. As with semiconductors, the trick is to not exceed the "junction" temperature. As always, follow the manufacturer's recommendations then add your own fiddle factor. MIL 217 taught me a lot.
David G3UNA We've drifted off this thread subject somewhat, my apologies. > Dave, > > I can vouch for that statement. I do use the Caddock Thick Film 50 ohm > resistors as precision dummy loads. They are flat up to 500 MHz with > good mounting using no leads. They MUST be mounted on a heat sink, and > yes, they will go open in a flash if the rated power is exceeded (don't > bother to ask me how I know that). > > So, recommending them for a K3 application may not be the best, but if > you want an inexpensive dummy load, got a heat sink from a defunct > computer CPU cooling device and one of those resistors and connect it to > a BNC or UHF jack using zero length leads - but don't exceed its power > rating (they are available up to 100 watts). > > 73, > Don W3FPR > > David Gilbert wrote: >> Metal film resistors are notoriously fragile. They will typically meet >> their published dissipation specs just fine, but they go from being OK >> to being an open in a flash (literally) when overstressed. I personally >> would never use one in any application where the power they were >> expected to handle wasn't rigid controlled. Check with any industrial >> control manufacturer and you will hear the same story. >> >> 73, >> Dave AB7E >> >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
