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#41
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On 2012-10-03, Geoffrey S. Mendelson wrote:
My choices are to once a week clean out a jam, and clean the feed roller; print something everyday (a waste of paper) load the paper tray with scrap paper, use the bypass when you want to print something for real. another option is to make a document with no ink and print that each day at the end of the week collect the blank pages from the output tray and put them back in the input tray. -- ⚂⚃ 100% natural --- news://freenews.netfront.net/ - complaints: --- |
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#42
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On 03/10/2012 00:49, William Sommerwerck wrote:
"David Woolley" wrote in message ... William Sommerwerck wrote: My new computer has a solid-state "hard disk", and you wouldn't believe how fast it boots up, or how fast programs start to run. These, if flash memory, do have a definite wear out mechanism, although they do try to avoid writing to the same spot, even if the software does, to mitigate this. Correct. SSDs are an exception. They contain "leveling" software that makes sure the disk is written to evenly. The Crucial disk I use is spec'd at about 40TB of total writes. For most usage scenarios the theoretical lifetimes of modern SSDs are longer than HDDs. |
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#43
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On 10/03/2012 09:41 PM, Jeff Liebermann wrote:
On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs wrote: I don't know of any data that supports this common idea, but I'd be interested in reading about it if anybody's actually done the experiment carefully. It's an accelerated life test. The deration curve of the incandescent light bulb is well known and assumed to be (Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3544HPX_Catalog_2_11_09.pdf See Fig 5 on Pg 5 for the graph. Nobody wants to wait 1000 hours for a bulb to blow. So, they increase the applied voltage, which dramatically decreases the lifetime down to reasonable test times. Using a rack of bulbs, they obtain an average (or median) lifetime at the higher voltage. Then, they work backwards on the curve to estimate what it would be at the design voltage. You can't run an accelerated life test when the exponent isn't known more accurately than 12 to 16. When I was specifying lamps for a direction finder for the USCG, I had to deal with minimum lifetime specs. I asked the vendor (Dialight) how they tested their T-1 3/4 bulbs and was told that they did an accelerated lifetime test on a few bulbs from each lot to insure adequate lifetime along with the usual sampled 1.5% AQL failure test. Electromigration is a smaller effect in an AC bulb, since the leading order effect cancels. Yep. As I understand it (possible wrong), AC filaments break in the middle, mostly from vibration flexing. I don't think so, because there's no mechanism for that, as I said. The wire is fully annealed at all times, so there's no possibility of progressive fatigue failure. I suspect that the notion that cycling is hard on bulbs comes from the way that the bulb often fails at turn-on, when the thinnest hot spot vapourizes before the rest of the filament has a chance to come up to temperature and reduce the inrush current. Yep. See my comments on the relatively high failure rate on the 40watt theater marquee lamps due to cycling. The same lamps in the lobby and foyer were not cycled and seemed to last forever. I was actually disagreeing with you. There are lots of possible reasons for the marquee lights failing prematurely. I'm not a tungsten expert myself, so I'd be very interested in seeing actual data that shows a dramatic shortening of life due to cycling. I'm not saying it's impossible, just that I haven't seen any such data. The tungsten in the lamp is run within a few hundred kelvins of its melting point, so it's always in the fully annealed state, which ought to mean that there are no metal fatigue mechanisms operating, just material migration due to sublimation. Yep, but different failure mode. When the extremely thin layer of tungsten plating evaporates, the light becomes dimmer. Below some brightness level, it is considered to have failed. However, most such tungsten coated filaments fail due to corrosion of the base steel alloy wire which is exposed to the internal gases inside the bulb after the tungsten evaporates. The gases (mostly nitrogen and some argon) are inert, but there's a little water vapor outgassing from heating the glass envelope, which eventually corrodes the filament. Other failure modes are hot spots and notches caused by manufacturing variations and tungsten evaporation. The filament isn't tungsten-plated, it's pure tungsten or a low alloy. The brightness drop comes from tungsten condensing on the envelope. And the connecting wire isn't plain steel, it's generally Dumet, http://www.jlcelectromet.com/dumetwire.htm which is a 42% Ni steel with OFHC copper or nickel plating. You're making a lot of that up. I'd still like to see carefully-collected data. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
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#44
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On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs
wrote: On 10/03/2012 09:41 PM, Jeff Liebermann wrote: On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs wrote: I don't know of any data that supports this common idea, but I'd be interested in reading about it if anybody's actually done the experiment carefully. It's an accelerated life test. The deration curve of the incandescent light bulb is well known and assumed to be (Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3544HPX_Catalog_2_11_09.pdf See Fig 5 on Pg 5 for the graph. Nobody wants to wait 1000 hours for a bulb to blow. So, they increase the applied voltage, which dramatically decreases the lifetime down to reasonable test times. Using a rack of bulbs, they obtain an average (or median) lifetime at the higher voltage. Then, they work backwards on the curve to estimate what it would be at the design voltage. You can't run an accelerated life test when the exponent isn't known more accurately than 12 to 16. True, but I believe that's the range expected from different types of light bulbs (nitrogen filled, halogen, vaccuum), and not the range expected for a given device. I suspect that more accurate exponent value could be empirically determined for a given device, and later used only for that device. Yep. As I understand it (possible wrong), AC filaments break in the middle, mostly from vibration flexing. I don't think so, because there's no mechanism for that, as I said. The wire is fully annealed at all times, so there's no possibility of progressive fatigue failure. http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filament_evaporat ion One of the problems of the standard electric light bulb is evaporation of the filament. Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. The hot spots evaporate faster than the rest of the filament, increasing resistance at that point a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Note the photo of the filament with a break in the middle. When I was quite young, I would break burnt out AC light bulbs to see what was inside. If the filament was intact, the break was always somewhere near the middle. If a piece broke off, one end of the broken piece was usually near the middle. In later years, I would look at the remains of DC panel lights (usually type 47 for old Motorola radios) and noted that the breaks were always near the supporting terminals, probably due to metal migration. I suspect that the notion that cycling is hard on bulbs comes from the way that the bulb often fails at turn-on, when the thinnest hot spot vapourizes before the rest of the filament has a chance to come up to temperature and reduce the inrush current. Yep. See my comments on the relatively high failure rate on the 40watt theater marquee lamps due to cycling. The same lamps in the lobby and foyer were not cycled and seemed to last forever. I was actually disagreeing with you. There are lots of possible reasons for the marquee lights failing prematurely. I'm not a tungsten expert myself, so I'd be very interested in seeing actual data that shows a dramatic shortening of life due to cycling. I'm not saying it's impossible, just that I haven't seen any such data. So much for my anecdotal data. My theater marquee experience was in about 1966. The theater actually did keep records so that they could stock enough replacement bulbs, but I don't have copies of any of that. I tried Googling for similar repetative on-off tests and didn't find anything. If I have time, I'll try again. I must admit that the lack of test data does look suspicious. Perhaps sending the idea to Mythbusters and have them runs a test? The filament isn't tungsten-plated, it's pure tungsten or a low alloy. The brightness drop comes from tungsten condensing on the envelope. Oops. I thought it was plated. And the connecting wire isn't plain steel, it's generally Dumet, http://www.jlcelectromet.com/dumetwire.htm which is a 42% Ni steel with OFHC copper or nickel plating. You're making a lot of that up. I'd still like to see carefully-collected data. No, not fabricated. It's my reliance on my memory in an area that I'm not familiar with. I tried Googling for the wire used, couldn't find much, and made a bad guess. The plating came from somehow getting thorium coated tungsten wire used in vacuum tubes mixed up with light bulbs. Sorry for the errors and muddle. Cheers Phil Hobbs -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#45
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On Wed, 3 Oct 2012 10:34:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote: Tom Biasi wrote: Not so. With mechanical devices, regular moderate use provides a longer useful lifetime than using the device only rarely. I don't agree but will say no more. Laser printers. I have given away for parts several laser printers because they sat unused 99% of the time, and started to jam when I printed the one or two pages a month I needed them for. I've seen flat spots on laser printers. However, just running a few pages through the printer usually returns them to normal. If not, use some rubber roller restorer to soften the rubber. http://www.fixyourownprinter.com/specials/misc/all/S03 In my experience, many printer jams are caused by paper slippage on the rollers. Usually, it's the white paper dust that causes slippage, but it can easily be household dust accumulated over the time the printer was idle. Maybe hitting the printer with a compressed air blast before operating might help. Another slippage problem is when the rubber surface becomes glazed or polished. The rubber roller restorer will take the surface gloss off the rollers, and improve the traction, but if there's any rubber wear, the roller(s) should be replaced. Not only did the rubber wheels dry out and lose their ability to grab paper, they flatten where they are pressed against something. I have a perfectly good Samsung laser printer in that condition now. Ugh. I don't have much nice to say about Samsung printers. They're cheap, function adequately, use overpriced toner carts, and don't last very long. I've never really done an autopsy to isolate a culprit. The usual end of life symptoms are either paper jams or flimsy broken plastic parts. My choices are to once a week clean out a jam, and clean the feed roller; print something everyday (a waste of paper); spend $15 for a new roller (including postage) and an hour to install it; or wait for a sale (every 2-3 months) and buy a newer faster, higher resolution model with a 2,000 page toner cartridge included for less than the cost of a full load toner. Chuckle. Yeah, that's about it. Next purchase, I suggest HP LaserJet printers. They have their own collection of problems, but parts and refills are commonly available and cheap. The printer cannibals sell used parts and assemblies fairly cheap on eBay. Also, expertise is more easily found: http://www.fixyourownprinter.com My favorite printer of the week is the HP 2300DN or DTN at between $90 to $220 used depending on condition and options. Favorite feature is double sided (duplex) printing. Geoff. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#46
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On Wed, 03 Oct 2012 19:42:21 -0400, "
wrote: My 39YO HP45 still works but the power switch is too flaky to be usable. I collect old HP LED type calculators. The HP 45 is well worth fixing and using. The switches tend to fail due to dirt accumulation and/or wearing a grove into the PCB contact area from overuse. I've repaired both problems. http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv018.cgi?read=131014 This is the dirt problem: http://i45.photobucket.com/albums/f96/geoff_q/gunk.jpg I couldn't find a photo of a grove worn in the contacts. I've been quite successful with just cleaning the switch area. I've also repaired missing gold problems with gold leaf. It was difficult, required a microscope, a steady hand, no air movement, and considerable patience. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#47
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On Oct 4, 12:43*pm, Jeff Liebermann wrote:
On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs wrote: On 10/03/2012 09:41 PM, Jeff Liebermann wrote: On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs *wrote: I don't know of any data that supports this common idea, but I'd be interested in reading about it if anybody's actually done the experiment carefully. It's an accelerated life test. *The deration curve of the incandescent light bulb is well known and assumed to be * *(Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3.... See Fig 5 on Pg 5 for the graph. *Nobody wants to wait 1000 hours for a bulb to blow. *So, they increase the applied voltage, which dramatically decreases the lifetime down to reasonable test times. Using a rack of bulbs, they obtain an average (or median) lifetime at the higher voltage. *Then, they work backwards on the curve to estimate what it would be at the design voltage. You can't run an accelerated life test when the exponent isn't known more accurately than 12 to 16. True, but I believe that's the range expected from different types of light bulbs (nitrogen filled, halogen, vaccuum), and not the range expected for a given device. *I suspect that more accurate exponent value could be empirically determined for a given device, and later used only for that device. Yep. *As I understand it (possible wrong), AC filaments break in the middle, mostly from vibration flexing. I don't think so, because there's no mechanism for that, as I said. *The wire is fully annealed at all times, so there's no possibility of progressive fatigue failure. http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filamen... * *One of the problems of the standard electric light bulb is * *evaporation of the filament. Small variations in resistivity * *along the filament cause "hot spots" to form at points of * *higher resistivity; a variation of diameter of only 1% will * *cause a 25% reduction in service life. The hot spots evaporate * *faster than the rest of the filament, increasing resistance * *at that point a positive feedback that ends in the familiar * *tiny gap in an otherwise healthy-looking filament. Note the photo of the filament with a break in the middle. *When I was quite young, I would break burnt out AC light bulbs to see what was inside. *If the filament was intact, the break was always somewhere near the middle. *If a piece broke off, one end of the broken piece was usually near the middle. *In later years, I would look at the remains of DC panel lights (usually type 47 for old Motorola radios) and noted that the breaks were always near the supporting terminals, probably due to metal migration. I suspect that the notion that cycling is hard on bulbs comes from the way that the bulb often fails at turn-on, when the thinnest hot spot vapourizes before the rest of the filament has a chance to come up to temperature and reduce the inrush current. Yep. *See my comments on the relatively high failure rate on the 40watt theater marquee lamps due to cycling. *The same lamps in the lobby and foyer were not cycled and seemed to last forever. I was actually disagreeing with you. *There are lots of possible reasons for the marquee lights failing prematurely. *I'm not a tungsten expert myself, so I'd be very interested in seeing actual data that shows a dramatic shortening of life due to cycling. *I'm not saying it's impossible, just that I haven't seen any such data. So much for my anecdotal data. *My theater marquee experience was in about 1966. *The theater actually did keep records so that they could stock enough replacement bulbs, but I don't have copies of any of that. I tried Googling for similar repetative on-off tests and didn't find anything. *If I have time, I'll try again. *I must admit that the lack of test data does look suspicious. *Perhaps sending the idea to Mythbusters and have them runs a test? The filament isn't tungsten-plated, it's pure tungsten or a low alloy. The brightness drop comes from tungsten condensing on the envelope. Oops. *I thought it was plated. And the connecting wire isn't plain steel, it's generally Dumet, http://www.jlcelectromet.com/dumetwire.htm which is a 42% Ni steel with OFHC copper or nickel plating. You're making a lot of that up. *I'd still like to see carefully-collected data. No, not fabricated. *It's my reliance on my memory in an area that I'm not familiar with. *I tried Googling for the wire used, couldn't find much, and made a bad guess. *The plating came from somehow getting thorium coated tungsten wire used in vacuum tubes mixed up with light bulbs. *Sorry for the errors and muddle. Cheers Phil Hobbs -- Jeff Liebermann * * 150 Felker St #D * *http://www.LearnByDestroying.com Santa Cruz CA 95060http://802.11junk.com Skype: JeffLiebermann * * AE6KS * *831-336-2558- Hide quoted text - - Show quoted text - Hi Jeff, Phil. First I know nothing about incandescent bulbs. But how about this as a model of why turning bulbs on and off might cause them to fail sooner. 1.) I think we all observe that bulbs tend to blow when you turn them on. (unless you knock the lamp over or something.) 2.) I assume that the failure is mostly due to the thinner ‘hot spots’ on the filament. Thinner regions heat up faster (higher resistance with equal current). 3.) Now even if the thinner region doesn’t blow, it still gets hotter and loses a bit more tungsten than the rest of the filament. (For that small amount of time that it’s turning on.) But still this means that turning on the bulb causes the thin region to become a bit thinner. And that’s it. Repeated on and off means that the thin region has a higher average temperature than the thick part of the filament. It evaporates faster and fails sooner. George H. |
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#48
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On 10/04/2012 02:57 PM, George Herold wrote:
On Oct 4, 12:43 pm, Jeff wrote: On Thu, 04 Oct 2012 10:03:21 -0400, Phil Hobbs wrote: On 10/03/2012 09:41 PM, Jeff Liebermann wrote: On Wed, 03 Oct 2012 10:32:57 -0400, Phil Hobbs wrote: I don't know of any data that supports this common idea, but I'd be interested in reading about it if anybody's actually done the experiment carefully. It's an accelerated life test. The deration curve of the incandescent light bulb is well known and assumed to be (Vapplied/Vdesign)^-12 to ^-16 * Life at design voltage http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3... See Fig 5 on Pg 5 for the graph. Nobody wants to wait 1000 hours for a bulb to blow. So, they increase the applied voltage, which dramatically decreases the lifetime down to reasonable test times. Using a rack of bulbs, they obtain an average (or median) lifetime at the higher voltage. Then, they work backwards on the curve to estimate what it would be at the design voltage. You can't run an accelerated life test when the exponent isn't known more accurately than 12 to 16. True, but I believe that's the range expected from different types of light bulbs (nitrogen filled, halogen, vaccuum), and not the range expected for a given device. I suspect that more accurate exponent value could be empirically determined for a given device, and later used only for that device. Yep. As I understand it (possible wrong), AC filaments break in the middle, mostly from vibration flexing. I don't think so, because there's no mechanism for that, as I said. The wire is fully annealed at all times, so there's no possibility of progressive fatigue failure. http://en.wikipedia.org/wiki/Incandescent_light_bulb#Reducing_filamen... One of the problems of the standard electric light bulb is evaporation of the filament. Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. The hot spots evaporate faster than the rest of the filament, increasing resistance at that point a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Note the photo of the filament with a break in the middle. When I was quite young, I would break burnt out AC light bulbs to see what was inside. If the filament was intact, the break was always somewhere near the middle. If a piece broke off, one end of the broken piece was usually near the middle. In later years, I would look at the remains of DC panel lights (usually type 47 for old Motorola radios) and noted that the breaks were always near the supporting terminals, probably due to metal migration. I suspect that the notion that cycling is hard on bulbs comes from the way that the bulb often fails at turn-on, when the thinnest hot spot vapourizes before the rest of the filament has a chance to come up to temperature and reduce the inrush current. Yep. See my comments on the relatively high failure rate on the 40watt theater marquee lamps due to cycling. The same lamps in the lobby and foyer were not cycled and seemed to last forever. I was actually disagreeing with you. There are lots of possible reasons for the marquee lights failing prematurely. I'm not a tungsten expert myself, so I'd be very interested in seeing actual data that shows a dramatic shortening of life due to cycling. I'm not saying it's impossible, just that I haven't seen any such data. So much for my anecdotal data. My theater marquee experience was in about 1966. The theater actually did keep records so that they could stock enough replacement bulbs, but I don't have copies of any of that. I tried Googling for similar repetative on-off tests and didn't find anything. If I have time, I'll try again. I must admit that the lack of test data does look suspicious. Perhaps sending the idea to Mythbusters and have them runs a test? The filament isn't tungsten-plated, it's pure tungsten or a low alloy. The brightness drop comes from tungsten condensing on the envelope. Oops. I thought it was plated. And the connecting wire isn't plain steel, it's generally Dumet, http://www.jlcelectromet.com/dumetwire.htm which is a 42% Ni steel with OFHC copper or nickel plating. You're making a lot of that up. I'd still like to see carefully-collected data. No, not fabricated. It's my reliance on my memory in an area that I'm not familiar with. I tried Googling for the wire used, couldn't find much, and made a bad guess. The plating came from somehow getting thorium coated tungsten wire used in vacuum tubes mixed up with light bulbs. Sorry for the errors and muddle. Cheers Phil Hobbs -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558- Hide quoted text - - Show quoted text - Hi Jeff, Phil. First I know nothing about incandescent bulbs. But how about this as a model of why turning bulbs on and off might cause them to fail sooner. 1.) I think we all observe that bulbs tend to blow when you turn them on. (unless you knock the lamp over or something.) 2.) I assume that the failure is mostly due to the thinner ‘hot spots’ on the filament. Thinner regions heat up faster (higher resistance with equal current). 3.) Now even if the thinner region doesn’t blow, it still gets hotter and loses a bit more tungsten than the rest of the filament. (For that small amount of time that it’s turning on.) But still this means that turning on the bulb causes the thin region to become a bit thinner. And that’s it. Repeated on and off means that the thin region has a higher average temperature than the thick part of the filament. It evaporates faster and fails sooner. George H. If the effect is real, that sounds like a good candidate for a mechanism. Certainly you'd expect that to be important right near the end of the bulb's life, so maybe it's important throughout. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
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#49
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On Thu, 4 Oct 2012 11:57:21 -0700 (PDT), George Herold
wrote: Hi Jeff, Phil. First I know nothing about incandescent bulbs. I'm still learning (mostly from my mistakes). I blundered across this video on tungsten filaments. http://www.youtube.com/watch?v=DIGqBb3iZPo 3:38 While it doesn't touch any of the issues previously mentioned, it does include some interesting info on how the filament is made and its structure. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#50
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On 10/3/2012 2:01 AM, MikeS wrote:
Using anything shortens it's working life. Seems to go against the whole ethos of exercising. Never get out of bed and live forever ... If you were an android that may be true. |
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