Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Cursitor Doom Newsgroups: sci.electronics.design Subject: Still a lot to be said for old technology (HP 432A RF power meter) Date: Mon, 01 Apr 2024 18:09:40 +0100 Organization: A noiseless patient Spider Lines: 12 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Mon, 01 Apr 2024 17:09:41 +0200 (CEST) Injection-Info: dont-email.me; posting-host="6abd7acbea44dc0d341b8a0e36c8afda"; logging-data="2750809"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+Ovba7PEU2Q8mc41F0K+A9twY1pWWN0Ho=" User-Agent: ForteAgent/8.00.32.1272 Cancel-Lock: sha1:LOanM2mJM3w8YzTLhfhYYvPIh48= Bytes: 1541 It's probably just my ignorance on this subject, but I find it remarkable how fast this HP thermistor is able to respond to even minute changes in temperature caused by variations in applied power. To my eye, the change is instantaneous. The meter needle flicks between different readings in the blink of an eye as the power is varied. I'd have expected some degree of thermal lag. I mean we're talking about only very tiny power levels like -30dbm. How much heat does that generate into 200 ohms? Yet any change is apparent with zero noticeable delay. https://disk.yandex.com/i/gUgUim-KogCOBw