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Speaking of I2R losses
I am currently playing with tuners... Specifically link coupled... And
I have been making my own condensers... Part of the exercise includes efficiency 'that' word again of power transfer, more specifically tank coil losses... I had been using my fingers as my calibrated temperature differential meter but I have gotten the tuners engineered to the point where there are not enough differences to tell by feel... So I purchased an Infrared measurement gun... fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again So, I have been running power soak measurements of the tuner components with the power source remaining energized during measurements - the nice part of a non contact instrument... The measurements turned up surprising results to me... The continuous power level was 680 watts input to the tuner box at 3508 kc ( two Bird meters, uncalibrated and the power averaged / 670 and 690 W. respectively)... The power soak time was ten minutes total... The outside air temperature was +12.1 F throughout the measurement period - mid day... The tuner components were +12.8 at the start (- + 0.2 F)... The tuner parts are in a plastic waste bin with the top on, except during measurements, to control air currents... The box sits about 4 feet away from the wall of a large building and shaded from direct sunlight weak sun at the time of measurement... The coil is ~4" diameter and consists of 20.5 feet (22 uH) of #10 enameled wire wound on a paper mailing tube, and glued down with epoxy.. The link coil is the same wire (2.2 uH) wound on PVC tubing and slid inside of the tank coil tube - it was not available for temperature measurement, a finger slid inside of the PVC tube did not detect any temperature rise power off!... The tank condensers are aluminum and are ~24 square inches in area per plate (a pair of caps in a series tank configuration)... At 5 and 10 minutes the top was popped and the surface temperature of the tank coil and condensers were measured - taking about 30 seconds - and the top replaced... The results for both times were within a few tenths of a degree... The coil was found to be +12.9 to +13.1 F and the condenser plates were +31.5 to +32.3 F... A result which sent me away mumbling to myself... Not what I expected... This is consistent with an earlier test in which the tuner was powered for 10 minutes at 1800 watts with the exciter sending dahs at 20 wpm ( typical contesting environment)... The components were finger measured power off and the coil felt to be barely above the starting temperature and the plates to be just a bit warmer than the starting temperature, which prompted the purchase of the infrared gun because it couldn't possibly be right - we all know that condensers are 100% efficient and coils are lossy - right?... denny / k8do |
Speaking of I2R losses
couldn't possibly be right - we all know that condensers are 100%
efficient and coils are lossy - right?... Good work. Congratulations on doing some real experimenting and thanks for reporting. What do you attribute the losses in the cap to? Could it be contact resistance between the plates and the rotor? Would it be possible to substitute some commercial cap temporarily to compare? Rick K2XT |
Speaking of I2R losses
Rick wrote:
couldn't possibly be right - we all know that condensers are 100% efficient and coils are lossy - right?... Good work. Congratulations on doing some real experimenting and thanks for reporting. What do you attribute the losses in the cap to? Could it be contact resistance between the plates and the rotor? Would it be possible to substitute some commercial cap temporarily to compare? Rick K2XT Show me a 100% efficient cap first, then I will show you where to patent it and sell it. You will then have the money to purchase my bridge in the desert! Regards, JS |
Speaking of I2R losses
John Smith wrote:
Rick wrote: couldn't possibly be right - we all know that condensers are 100% efficient and coils are lossy - right?... Good work. Congratulations on doing some real experimenting and thanks for reporting. What do you attribute the losses in the cap to? Could it be contact resistance between the plates and the rotor? Would it be possible to substitute some commercial cap temporarily to compare? Rick K2XT Show me a 100% efficient cap first, then I will show you where to patent it and sell it. You will then have the money to purchase my bridge in the desert! Regards, JS Of course, there must be lossless caps somewhere, huh? Because a cap with no dielectric would suffer no losses (ignoring the resistance of the plates to the inrush, exhaust of electrons), huh? So then, a cap consisting of plates in a vacuum would have no dielectric and no loss. Strange, I seem to still notice a loss in such a device when examined mathematically. Perhaps the ether is serving as a dielectric? Chuckling, JS |
Speaking of I2R losses
Rick wrote:
What do you attribute the losses in the cap to? Besides I^2*R losses in the leads, there are dielectric losses in the dielectric. Ever use a disc-ceramic to try to pass one amp of RF? My experience is that it will light up the night sky. :-) -- 73, Cecil http://www.w5dxp.com |
Speaking of I2R losses
John Smith wrote:
Of course, there must be lossless caps somewhere, huh? There's some in EZNEC. :-) -- 73, Cecil http://www.w5dxp.com |
Speaking of I2R losses
Well, there are dielectrics and there are . . . ummm well you get the point... In this case the main dielectric of my condensers is glass, probably stannous float bath soda glass... 0.100" thick with an aluminum plate on each side... After my fingers had found the disparate temperature rise on an early test I did a literature search for the dielectric constant and loss factor of glass and discovered that not all glass is equal - or as Orwell put it, some of the animals are more equal than the others... Anyway, Soda glass has a loss tangent of 0.01 to 0.05 and a dielectric constant of 6 - and Borosilicate glass (Pyrex) has a loss tangent of 0.001 to 0.002 and a dielectric constant of 4... So, it would appear that Borosilicate glass is better as a low loss dielectric... The trade off is that with 1/3 lower Dielectric Constant I would have to increase my plate areas by 1/3 to maintain the same capacity... The jury is out on this... 3.5 mc is relatively low frequency... I am not sure how much of the heating is due to the loss factor of the glass and how much is I2R heating from the current flowing across the plates... I spoze I could order some custom made 8" X 10" X 0.100" Pyrex plates and compare otherwise identical condensers... OTOH, I spoze some of the more equal animals in my house would complain over sticks and stones in their xmas stockings after I pay for the Pyrex... denny / k8do |
Speaking of I2R losses
Cecil Moore wrote:
Rick wrote: What do you attribute the losses in the cap to? Besides I^2*R losses in the leads, there are dielectric losses in the dielectric. Ever use a disc-ceramic to try to pass one amp of RF? My experience is that it will light up the night sky. :-) Cecil: What is the best fly wing scale you have? I would think specs would call for one capable of 0.00000000000000000000000000000000000000000000001 gm resolution ... Well, Santas coming, hang out a big sock! Scratching head, JS |
Speaking of I2R losses
On 4 Dec 2006 06:07:44 -0800, "Denny" wrote:
.... So I purchased an Infrared measurement gun... fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again It is not such a digression. You should do make measurements of the temperature of different materials that you know are at the same temperature, and see what results you get from your non-contact thermometer. The emissivity of the surface is an important factor that limits the absolute accuracy of these things. It is an interesting experiment that you have described, though I am not sure that surface temperature (if it is accurate) alone is a good indicator of the power flow to the air. For example, would you expect that the temperatures of natural coloured and black aluminium heatsink to be the same if dissipating the same (non zero) power in the same environment? Extending that to your experiment, is dark enamelled copper wire (as may be used in a coil) a better black body radiator than bright aluminium (as may be used in a capacitor). Owen -- |
Speaking of I2R losses
Owen Duffy wrote:
On 4 Dec 2006 06:07:44 -0800, "Denny" wrote: ... So I purchased an Infrared measurement gun... fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again It is not such a digression. You should do make measurements of the temperature of different materials that you know are at the same temperature, and see what results you get from your non-contact thermometer. The emissivity of the surface is an important factor that limits the absolute accuracy of these things. It is an interesting experiment that you have described, though I am not sure that surface temperature (if it is accurate) alone is a good indicator of the power flow to the air. For example, would you expect that the temperatures of natural coloured and black aluminium heatsink to be the same if dissipating the same (non zero) power in the same environment? Extending that to your experiment, is dark enamelled copper wire (as may be used in a coil) a better black body radiator than bright aluminium (as may be used in a capacitor). Owen -- And of course, the magnitude of the surface area over which the power is being dissipated will also influence the temperature rise of the small area being measured by the instrument. Measured temperature differences of the same material and at the same distance (under different experimental conditions) are likely to be more accurate than absolute measurements with unknown emissivity. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Speaking of I2R losses
K8DO writted: :-)
So I purchased an Infrared measurement gun... So what kind and price? 73 Yuri |
Speaking of I2R losses
Owen Duffy wrote: On 4 Dec 2006 06:07:44 -0800, "Denny" wrote: ... So I purchased an Infrared measurement gun... fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again It is not such a digression. You should do make measurements of the temperature of different materials that you know are at the same temperature, and see what results you get from your non-contact thermometer. The emissivity of the surface is an important factor that limits the absolute accuracy of these things. It is an interesting experiment that you have described, though I am not sure that surface temperature (if it is accurate) alone is a good indicator of the power flow to the air. For example, would you expect that the temperatures of natural coloured and black aluminium heatsink to be the same if dissipating the same (non zero) power in the same environment? Extending that to your experiment, is dark enamelled copper wire (as may be used in a coil) a better black body radiator than bright aluminium (as may be used in a capacitor). Owen -- Actually, unless the heat sink gets pretty hot relative to its surroundings, a large percentage of the heat loss is convective, not radiative, assuming we're operating in air at normal atmospheric pressures. It all gets much more interesting in a good vacuum. If I got the numbers right, for example, blackbody radiation at 280K is about 35 milliwatts/cm^2, and at 300K it's about 46 milliwatts/cm^2. So 20C above roughly room temperature ambient gets you a whopping net 11 milliwatts/cm^2 to radiation. (Fins facing each other don't help radiation, but do help convection.) Cheers, Tom |
Speaking of I2R losses
Owen Duffy wrote: On 4 Dec 2006 06:07:44 -0800, "Denny" wrote: ... So I purchased an Infrared measurement gun... fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again It is not such a digression. You should do make measurements of the temperature of different materials that you know are at the same temperature, and see what results you get from your non-contact thermometer. The emissivity of the surface is an important factor that limits the absolute accuracy of these things. It is an interesting experiment that you have described, though I am not sure that surface temperature (if it is accurate) alone is a good indicator of the power flow to the air. For example, would you expect that the temperatures of natural coloured and black aluminium heatsink to be the same if dissipating the same (non zero) power in the same environment? Extending that to your experiment, is dark enamelled copper wire (as may be used in a coil) a better black body radiator than bright aluminium (as may be used in a capacitor). Owen -- (I apologize for not thinking of this in time to include it in my previous posting...) Remember, too, that what looks "black" to us in the visible spectrum may be quite different over the spectrum including most of the radiation, especially when the object is only about 250K to 350K. At 300K, the peak of black body radiation occurs at about 10 microns, less than 1/10000th the frequency of visible light. I suppose heat sinks are dyed black more because we think they should look black than because it does any good thermally. And avoid buying heat sinks that are PAINTED black; the paint just adds to the thermal resistance. Cheers, Tom |
Speaking of I2R losses
K7ITM wrote: Owen Duffy wrote: On 4 Dec 2006 06:07:44 -0800, "Denny" wrote: ... So I purchased an Infrared measurement gun... fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again It is not such a digression. You should do make measurements of the temperature of different materials that you know are at the same temperature, and see what results you get from your non-contact thermometer. The emissivity of the surface is an important factor that limits the absolute accuracy of these things. It is an interesting experiment that you have described, though I am not sure that surface temperature (if it is accurate) alone is a good indicator of the power flow to the air. For example, would you expect that the temperatures of natural coloured and black aluminium heatsink to be the same if dissipating the same (non zero) power in the same environment? Extending that to your experiment, is dark enamelled copper wire (as may be used in a coil) a better black body radiator than bright aluminium (as may be used in a capacitor). Owen -- (I apologize for not thinking of this in time to include it in my previous posting...) Remember, too, that what looks "black" to us in the visible spectrum may be quite different over the spectrum including most of the radiation, especially when the object is only about 250K to 350K. At 300K, the peak of black body radiation occurs at about 10 microns, less than 1/10000th the frequency of visible light. I suppose heat sinks are dyed black more because we think they should look black than because it does any good thermally. And avoid buying heat sinks that are PAINTED black; the paint just adds to the thermal resistance. Cheers, Tom Shoot, make that "less than 1/10th the frequency of visible light," but still darned little radiated in the visible region. There's cool 'speriment using a spherical flask of visibly opaque liquid to focus IR radiation to a point where you can feel it very easily. What you see in the visible spectrum isn't what IR "sees." Cheers, Tom |
Speaking of I2R losses
stannous float bath soda glass... Denny Please, what is this? stannous float? something to do with tin? Thanks John AB8O |
Speaking of I2R losses
On 4 Dec 2006 06:07:44 -0800, "Denny" wrote:
fascinating little instrument - did you know that on a clear day with the air temperature +12.1 F and zero wind, that a 5 foot diameter black rubber tractor tire facing the clear sky to the North can have a surface temp of -2.6 to -3.0 F? I didn't but that is what I found... OK, I digress again Hi Denny, More fascinating was that everyone missed the significance of the reported temperature. The coil was found to be +12.9 to +13.1 F and the condenser plates were +31.5 to +32.3 F... A result which sent me away mumbling to myself... Not what I expected... OK, another surprise. we all know that condensers are 100% efficient and coils are lossy - right?... Of course, and then the conversation went towards power factors and such. Didn't Georg Simon Ohm die for all your sins, folks? You need another specialized piece of test gear - in tribute to our departed Reggie's folk-hero: a Kelvin Bridge Ohm Meter. Don't ask for one at Radio Shack. When (and if) you get one, try measuring the resistance of your home made cap (and I don't mean lead-to-lead, but lead-to-plate, and for each plate, and for each lead connection). For those who would press a Radio Shack Ohm Meter into this service, a gratuitous -Chuckle- 73's Richard Clark, KB7QHC |
Speaking of I2R losses
Richard, I doubt many of us have to go buy a Kelvin Bridge Ohmmeter
from eBay to get what you're after. I've got a Radio Shack meter with a 300mV scale; I've got a hefty power supply with current limit, and I've got a 55 watt, 12V fog lamp. I'll admit, I had to think pretty hard to figure out where I had a load resistor to keep my power supply from going into overcurrent shutdown, but it's on the premises, so it counts ;-) I think I can do milliohm measurements of no more dubious accuracy than the voltage and current accuracy of my Radio Shack meter in the vicinity of 4.5A and 4.5mV Long live four wire resistance measurements! Denny, I'd be interested in whether or not lead resistance was a major loss component if you want run a few amps DC through your cap lead / plate connection and measure the voltage drop. 73, Dan |
Speaking of I2R losses
On 4 Dec 2006 22:20:34 -0800, "
wrote: Long live four wire resistance measurements! Hi Dan, A Cigar to the man who knows how to parlay Radio Shack into a winner! 73's Richard Clark, KB7QHC |
Speaking of I2R losses
In my usual habit I'll reply off the bottom of the que... Lots of good comments and suggestions... In no particular order: I suspect the surface of the black tire had cooled below ambient by convective radiation... Happens to my windshield on mornings above freezing ambient whilst the windshield will be a skim of ice... Though the thought of what the tire might read under non-convective conditions occurred and was duly filed away in that great container in my head for further inspection... Actually I use the Rubble Method for filing information.. That is everything in my head is tossed on a great heap of rubble, and as I stir through the pile looking for one item, interesting bits of flotsam and jetsam flow back to the top of the heap for inspection, "oooh ya, I remember that!" Yes, the thought that there might be unwanted resistance in the connections to the condenser plates occurred and remains to be investigated... The connecting wire is the #10 magnet wire forming the coil and is firmly bolted with #8 brass hardware and flat washers to a 1"x1" tab formed on the edge of the plate when I cut the plates from a sheet... For Yuri, congratulations on the CQ160 win(s), nice job my friend... Drop me a description of his antenna setup... Wanna be's like me are always looking for an edge... On the IR gun, it was in the ~$65 range on sale, as their economy model, I don't remember who the internet vendor is, I can get you the make and model if you need it... But just do a search, lots of sources and prices... The little bit I have used it I have been satisfied with the readings - nothing rings my 'no-way, Jose!' meter, so far... The 35' long radiant tube heater in my shop shows ~375-385 F at the mid point from 8 feet away, which is about right as it will not ignite paper on contact I tried though it makes it brown - paper has an ignition temp of ~454 F per Ray Bradbury at least... The gun has a laser spot so you can see where the detector is aimed and the size of the spot is proportional to the area being measured at that distance... I suspect that dielectric loss in the soda glass is the prime contributor to the temperature rise on the plates... There is a significant amount of joules passing through the glass as strain in the dielectric.. Oh yeah, the question on the type of glass... Bad habits as an old lab rat surfaced when I wrote that... Common window glass is float formed on molten tin, and that is what my old chemical stained brain popped out as 'stannous'... On differential IR readings from the surface of various materials - well I can't say for sure as my credentials in thermodynamics are shaky at best (picture me shuddering in pain at the memories of Schrodinger equations and those IBM punch cards we used to program the computer in the physics lab 40 years ago - 'the horror, the horror'..... But, all the materials in the tuner were within a few tenths when at ambient, so I have no reason to suspect a gotcha when midly warmed... denny / k8do - often confused but never in doubt... |
Speaking of I2R losses
Brain fart - substitute "radiation cooling" for 'convective cooling' in
my last post.. The thought struck me as I was wandering down the hallway that I had a senior moment when I used the term convective for cooling to the sky by radiation, duh... denny - hey, even Einstein had his moments see Cosmological Constant |
Speaking of I2R losses
Denny wrote:
Brain fart - substitute "radiation cooling" for 'convective cooling' in my last post.. The thought struck me as I was wandering down the hallway that I had a senior moment when I used the term convective for cooling to the sky by radiation, duh... denny - hey, even Einstein had his moments see Cosmological Constant Denny: Maybe try a peltier junction next? grin Regards, JS |
Speaking of I2R losses
K8DO wrote:
For Yuri, congratulations on the CQ160 win(s), nice job my friend... Drop me a description of his antenna setup... Wanna be's like me are always looking for an edge... On the IR gun, it was in the ~$65 range on sale, as their economy model, I don't remember who the internet vendor is, I can get you the make and model if you need it... But just do a search, lots of sources and prices... The little bit I have used it I have been satisfied with the readings - nothing rings my 'no-way, Jose!' meter, so far... Any info on the IR gun would be appreciated, sounds, like right one for what I want to use it (check the loading coils etc.) Thanks! Wal's station rocks, even with this rusty OF. I put some pictures on our Tesla web site www.TeslaRadio.org, click on PHOTOS and W8LRL. It will be our goal to beat it from N2EE. We just came back from some slave labor of love, clearing more brush in freezing windy WX, leveling the field for RF :-) Waitng for the swamp to freeze so we can walk around and fix the antennas. 73 Yuri, K3BU |
Speaking of I2R losses
... paper has an ignition temp of ~454 F per Ray Bradbury at least.... Actually, the name of his book is/was "451 Fahrenheit", not 454, but you were close! -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor Certified Instructor for the Kansas Concealed-Carry Handgun license |
Speaking of I2R losses
"Denny" wrote in message ups.com... Well, there are dielectrics and there are . . . ummm well you get the point... In this case the main dielectric of my condensers is glass, probably stannous float bath soda glass... 0.100" thick with an aluminum plate on each side... After my fingers had found the disparate temperature rise on an early test I did a literature search for the dielectric constant and loss factor of glass and discovered that not all glass is equal - or as Orwell put it, some of the animals are more equal than the others... Anyway, Soda glass has a loss tangent of 0.01 to 0.05 and a dielectric constant of 6 - and Borosilicate glass (Pyrex) has a loss tangent of 0.001 to 0.002 and a dielectric constant of 4... So, it would appear that Borosilicate glass is better as a low loss dielectric... The trade off is that with 1/3 lower Dielectric Constant I would have to increase my plate areas by 1/3 to maintain the same capacity... The jury is out on this... 3.5 mc is relatively low frequency... I am not sure how much of the heating is due to the loss factor of the glass and how much is I2R heating from the current flowing across the plates... I spoze I could order some custom made 8" X 10" X 0.100" Pyrex plates and compare otherwise identical condensers... OTOH, I spoze some of the more equal animals in my house would complain over sticks and stones in their xmas stockings after I pay for the Pyrex... denny / k8do Could you use some Pyrex disk, I think I have some that are about a foot in diameter. If I can find them they are yours for the postage. |
Speaking of I2R losses
He has quite a receiving system... makes my active array look puny..
I did not get out to the radio station yesterday... I will today and will TRY to remember to make note of the IR Gun for you.. I am satisfied with it... ORION problems !?! I hope not... I have a brand new one as the #1 radio... It seemed to work well in CQWW CW.. As a SO SB 80M LP entry I worked 69 countries, a new high for me from the RF hole of Michigan... The score will not be impressive as I made zero effort to run stations, instead cruised the band for multipliers as a test of my new antenna arrays for 80M this year... Last nite I kept waking up thinking about 160 antennas and I can feel a new plan coming together in the hidden recesses of my twisted mind... Why oh why, can't my brain do this in June? Gawd I hate climbing towers in blowing snow and 20 degrees... denny / k8do Yuri Blanarovich wrote: K8DO wrote: For Yuri, congratulations on the CQ160 win(s), nice job my friend... Drop me a description of his antenna setup... Wanna be's like me are always looking for an edge... |
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