Re: I'm pretty sure it's just marketing.

Post #301,326 by Ashton 12/21/08 10:04:26 PM Reply	Re: I'm pretty sure it's just marketing. Maybe the IGBT was a lot more expensive then (maybe also less reliable?) Now the reduction in shipping cost may factor in '08. Thought you were a ChE, not EE I? I'm wondering though, if the 'throttling', while reducing power through the magnetron -- might just dump the excess resistively. That's the sort of thing marketing, even if they understood the implications (sure..) would willingly gloss-over. Either way, it must have an interesting power factor.. minor, unless everyone had one. Damn, nothing is simple (again.) If the paper has techno details, diagrams, would appreciate a copy. Maybe it will go into what happens to the plasma in the magnetron, whether fil. voltage/current are also reduced..? and like that. (A few cohorts time-shared at Varian, developing klystrons and 'other'; RF is interesting stuff, but to grok to fullness one needs to be more conversant than I, with Mr. Maxwell's, 'transverse modes in waveguides' and related arcanery.)
Post #301,328 by static 12/21/08 10:15:17 PM Reply	It sounds like they just shorten the cycle time. A non-"variable-power" microwave obviously cycles on-off for a few seconds at a time. From looking at the excerpt above, they use a PWM system to vary the power to the magnetron. This means on-off cycles of a fraction of a second. :-) Wade.
Post #301,443 by Another Scott 12/23/08 8:09:43 PM Reply	I found a copy. (Yeah, I'm a EE. It's in my genes, I think. :-) The paper's about 380 kB. (I keep forgetting to bring it home.) Assuming I don't forget tomorrow, should I send a copy to your VOM address? I haven't studied it in detail, but it seems to have a good description of the way the circuit works (along with a couple of simplified schematics). It talks about 2 power levels (600 W and 700 W), but I don't see a reason why those would be magic values (but again I haven't read it closely). Cheers, Scott.
Post #301,465 by Ashton 12/24/08 5:25:59 AM Reply	Yes, please --> vom The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. -- H.L. Mencken
Post #301,510 by Another Scott 12/24/08 6:53:37 PM Reply	Sent.
Post #301,511 by Ashton 12/24/08 7:42:50 PM Reply	ACK/NAK .pdf nicely legible. Will send my reading of its tea leaves and trade-offs, anon. Hmmm '91 then ... actual product in '08? Must be a story there. Thanks much.. schematics: EE-mantras.
Post #301,512 by Another Scott 12/24/08 7:48:19 PM Reply	I think they're different companies. The paper was by folks at Toshiba. I doubt that it was so unique that other microwave oven manufacturers couldn't have come up with their own versions if they chose. Have fun! Cheers, Scott.

Welcome to IWETHEY!