| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Oct 16 01:03PM -0400 >> e.g. plastic or glass. A dab of grease or some tape will make it work a >> lot better. > I have not experienced that issue, for the record. What I find is that accuracy starts to suffer as the battery gets weak. I view them the same as smoke-alarm batteries - 2x per year, whether I need it or not. And the used batteries are put aside for my increasing number of novelty radios that the grandkids are fighting over. Not in them, but with them for demonstration purposes. Your accuracy requirements aren't high, then. A shiny metal surface can easily show up as 90% room reflection and 10% surface emission. A bit of tape will reverse those numbers. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net https://hobbs-eo.com |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Oct 16 11:19AM -0700 On Tuesday, October 16, 2018 at 1:03:31 PM UTC-4, Phil Hobbs wrote: > Your accuracy requirements aren't high, then. A shiny metal surface can > easily show up as 90% room reflection and 10% surface emission. A bit > of tape will reverse those numbers. Perhaps not. 90% of the use is to verify that I am not looking at a freeze-out on an AHU coil or at the discharge temperature of a chiller. And in such cases, it is pretty much go/no-go. I am not the mechanic, but I have learned over the years that "trust but verify" does not only apply to the former Soviets. But, for 10% of the use, it is to let office workers, docs or other staff know the temperature in their space. The docs have, on more than a few occasions, pulled out a thermometer of their own - and so far, they and my little heat gun have agreed. On rare occasion, I will use it at home to verify radiator temperature against the gauge on the boiler, or to look for hot-spots in some bit of audio or radio equipment, or other. And, if one tube on an output pair is acting differently from another, I understand I have an issue. Peter Wieck Melrose Park, PA |
| jurb6006@gmail.com: Oct 16 12:35PM -0700 >"Provided they're really undisturbed. Thermal cycling can cause delamination problems that don't occur with the oil present. " What I consider the better TO-3s are aluminum, not steel. Another advantage is that they won't bend as much if the mounting surface is not perfectly flat. T |
| Phil Allison <pallison49@gmail.com>: Oct 16 04:54PM -0700 > What I consider the better TO-3s are aluminum, not steel. ** Though once common, Aluminium TO3 paks are no longer used by most manufacturers due to problems with thermal expansion of the aluminium base causing microscopic cracking of silicon chips. Thermal expansion of aluminium is about 7 times greater than that of silicon, limiting the number of full thermal cycles such devices were good for. https://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html Steel and copper alloy packs are used instead, with most having a "coin" made of a metal with intermediate rate of expansion soldered between the chip and the pak. > Another advantage is that they won't bend as much if the mounting > surface is not perfectly flat. ** Yuck. Better use only flat heatsinks. .... Phil |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 4 updates in 1 topic"
Post a Comment