RF Voodoo - Page 1
Forum section: electronics / general

author: German_EE
author_rank: Super Contributor
timestamp: September 09, 2014, 05:20:00 pm
content: The five or six talks in front of the white board with Doug Ford were very enjoyable. What you now need to do is borrow Shahriar from 'The Signal Path' to explain some of the RF Voodoo that we see on some of the teardowns. Strips of PCB copper sitting in splendid isolation, fan shapes and long strips of PCB material of precise length and width all need explaining.Should Shahriar not fancy a trip to Australia I'm sure that you could find an RF expert in the Greater Sydney area who might be prepared to do the job in exchange for a little sponsorship.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: September 09, 2014, 05:48:10 pm
content: Quote from: German_EE on September 09, 2014, 05:20:00 pmI can do a tutorial on microwave and mm-wave components both monolithic and on other types of substrate... I just need to find the time.

author: SeanB
author_rank: Super Contributor
timestamp: September 09, 2014, 06:31:52 pm
content: Good, the last time I was working on servicing microwave equipment a major requirement was being able to do plumbing.

author: Kostas
author_rank: Regular Contributor
timestamp: September 09, 2014, 06:35:16 pm
content: Quote from: SeanB on September 09, 2014, 06:31:52 pmWaveguide?

author: SeanB
author_rank: Super Contributor
timestamp: September 09, 2014, 06:48:25 pm
content: Waveguide, lots of it and lots of waveguide switches as well. Then couplers and microwave rigid coax cabling for the small stuff. Still have a set of ALNICO magnetron magnets around somewhere, from a magnetron that demagnetised itself in operation when the fan failed.

author: German_EE
author_rank: Super Contributor
timestamp: September 09, 2014, 07:10:00 pm
content: Good, thank you. The highest I've worked at is the 70cm band, about 440 MHz and even that was a struggle with hairpin inductors and cavity filters. As all of RF engineering seems to be going higher and higher in frequency this talk will be essential.

author: tggzzz
author_rank: Super Contributor
timestamp: September 09, 2014, 07:18:44 pm
content: Quote from: German_EE on September 09, 2014, 07:10:00 pm20 years ago (gulp) I realised in my gut that 60GHz was a seriously high frequency. Seeing the (lack of) size of a 20dB aerial was one factor. Seeing the thickness of a quarter-wave anti-reflection coating on the aerial was another.Not in Kansas anymore.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 09, 2014, 11:05:13 pm
content: Quote from: SeanB on September 09, 2014, 06:48:25 pmYikes, and AlNiCo is supposed to have a ridiculously high Curie temperature (not far from steel's)!Tim

author: SeanB
author_rank: Super Contributor
timestamp: September 10, 2014, 04:39:22 am
content: It was rather crispy, and as it ran at over 140C with the fan ( frictional heating in the nose) with no cooling and the 2kW input it did not stay happy long. New bearings in the fan and a service the fan ran again. The magnet was not much degraded, but the magnetron was well done.Biggest problem was the isolation switches were degrading as the ionisation trigger Amecurium needed to be replaced, you still had them operate but with a delay that grew as they aged, and you needed a higher voltage to strike them.