Coolant for dummy loads
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From: mpm on 1 Apr 2010 22:07 On Apr 1, 8:39 pm, "Phil Allison" <phi...(a)tpg.com.au> wrote: > <op...(a)hotmail.com> > > > > > I've been using engine oil as a coolant for dummy loads but am > > wondering whether something like peanut, sunflower or avocado oil > > would be better. > > ** Why use oil at all ?? > > It gets extremely hot and catches fire, is hazardous if spilled and is a > poor absorber of heat. > > ..... Phil The use of an oil dielectric will greatly reduce the physical size of the device. And you don't want the oil to absorb heat -- you want it to transfer the heat to the device's heat fins. The placement of the internal resistor (usually on a ceramic substrate) surround by oil, in the right shape cavity, will present a near perfect match (S11 response curve) to the transmitter. -mpm
From: Dave Platt on 1 Apr 2010 22:12 >> I've been using engine oil as a coolant for dummy loads but am >> wondering whether something like peanut, sunflower or avocado oil >> would be better. Engine oil gives off an awful smell when it breaks >> down, smells like rotten eggs. Can't find transformer oil. Any >> thoughts? >100% synthetic oil. Or, 100% "food-grade" mineral oil. Check with local animal-feed dealers... if I recall correctly it's used as a laxative for cattle and horses, and is available relatively inexpensively in gallon quantities. You can also buy it in small bottles at a drugstore, but it's much more expensive that way. -- Dave Platt <dplatt(a)radagast.org> AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads!
From: George Herold on 1 Apr 2010 22:23 On Apr 1, 9:39 pm, "Phil Allison" <phi...(a)tpg.com.au> wrote: > <op...(a)hotmail.com> > > > > > I've been using engine oil as a coolant for dummy loads but am > > wondering whether something like peanut, sunflower or avocado oil > > would be better. > > ** Why use oil at all ?? > > It gets extremely hot and catches fire, is hazardous if spilled and is a > poor absorber of heat. > > ..... Phil Air or water cooled Phil? (something else?) George H.
From: mpm on 1 Apr 2010 22:26 On Apr 1, 8:18 pm, "op...(a)hotmail.com" <op...(a)hotmail.com> wrote: > I've been using engine oil as a coolant for dummy loads but am > wondering whether something like peanut, sunflower or avocado oil > would be better. Engine oil gives off an awful smell when it breaks > down, smells like rotten eggs. Can't find transformer oil. Any > thoughts? You can buy here: Link: http://birdtechnologies.thomasnet.com/viewitems/accessories/coolants?&bc=100|1019
From: Phil Allison on 1 Apr 2010 22:51
"George Herold Troll" > > ** Why use oil at all ?? > > It gets extremely hot and catches fire, is hazardous if spilled and is a > poor absorber of heat. Air or water cooled Phil? ** Air does not catch fire and is a very poor heat absorber. Water is the ideal coolant for dummy load resistors ( for non RF applications) since the worst it can do is reach 100C and begin to boil. A 100 watt rated tubular resistor can easily absorb 1000 watts if submerged in a bucket of the stuff. ..... Phil |