How to mount microwave slug diodes - Page 1
Forum section: electronics / rf-microwave

author: Bud
author_rank: Super Contributor
timestamp: February 03, 2017, 04:05:38 am
content: I guess these type of diodes is supposed to be mounted in some sort of a coaxial holder? Can they be soldered on a PCB ?

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 03, 2017, 06:49:06 am
content: They're meant for detector diode mounts, which typically have a type-N connector on one side (RF in) and a PL-259 (aka 'UHF' connector) on the other side (detected voltage output). They may also be mounted inside waveguide with a probe and clamp. I don't think they can be PCB mounted.

author: David Hess
author_rank: Super Contributor
timestamp: February 03, 2017, 09:24:48 pm
content: Soldering them is not a good idea but in the past, they used clips which look like fuse clips to mount them to a circuit board.

author: LaserSteve
author_rank: Super Contributor
timestamp: February 03, 2017, 10:00:46 pm
content: Usually they get mounted in a waveguide. A thin mica washer goes up at the top of the guide wall, with a metal washer against it. This forms a RF return capacitor, and the pin sticks thru both washers and up thru the waveguide into a microwave choke, DC and IF output is then taken from the pin. Amateurs skip making the multidisc choke, as it is difficult to machine.The small flat area around the pin holds the washers against the waveguide. A clamp surrounds the bottom metal section as the return, and is connected to the waveguide. Soldering is lethal to the device, due to the low melting point solders used to mount the diode/semiconductor and whisker that contacts the diode.There are also coaxial holders of a different construction.Any of the RSGB microwave handbooks on VHF/UHF and Microwaves have a picture of the mount and how to construct one..If you can find the MIT Radiation Laboratory (radlab) Handbooks on line, you will learn more about these "detector" diodes then you ever wanted to know.Here is another way... Its missing the note to have mylar, cellophane tape, or kapton film around the choke body...http://www.next.gr/sens-detectors/10GHz-waveguide-detector-circuit-diagram-for-amateur-radio-l59473.htmlSteve

author: Bud
author_rank: Super Contributor
timestamp: February 04, 2017, 06:22:29 pm
content: Awesome, thanks for sharing the link,it was helpful.

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 04, 2017, 07:11:25 pm
content: What is your intended use? Putting it on a pcb is not something the manufacturer was thinking of obviously.Edit: Just opened this US Navy radar unit for you and took a picture

author: Bud
author_rank: Super Contributor
timestamp: February 04, 2017, 11:49:34 pm
content: Thanks for going to that troubleI want to get back on my project to build a power sensor head for the Marconi 6960https://www.eevblog.com/forum/testgear/marconi-6960-power-meter/and I was browsing eBay for microwave diodes and there was a lot of these slug diodes came up in search, so I was wondering if I can use one for my project.

author: David Hess
author_rank: Super Contributor
timestamp: February 05, 2017, 03:38:53 am
content: Quote from: Bud on February 04, 2017, 11:49:34 pmI would be careful about whether they are good or not. I have noticed that surplus equipment being sold at ham swap meets tends to have blown diodes if they were part of an HF slug.Other than the mount, what makes IN21 style microwave diodes microwave diodes? Gold doping like a switching diode?

author: Bud
author_rank: Super Contributor
timestamp: February 07, 2017, 03:38:39 am
content: Does anyone recognize the sensor part on this RF probe ?

author: LaserSteve
author_rank: Super Contributor
timestamp: February 07, 2017, 03:16:33 pm
content: I'm thinking that pic is more likely a thermocouple pair rather then a diode... But I could be very wrong.Steve

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: February 07, 2017, 06:59:59 pm
content: A while ago I made a video about Gunn diodes where I have show how they can be used to build a Gunnplexer - you can see how diode is mounted inside sometime around 35 min into a video.

author: Bud
author_rank: Super Contributor
timestamp: February 07, 2017, 07:05:57 pm
content: Quote from: LaserSteve on February 07, 2017, 03:16:33 pmSorry i should have mentioned the probe was from a RF peak power meter, so perhaps unlikely be using an averaging sensor element such as a thermocouple.

author: phenol
author_rank: Regular Contributor
timestamp: February 12, 2017, 08:10:59 am
content: could it be something like the Russian 6D24N diode found in detector heads of RF voltmeters?...

author: Bud
author_rank: Super Contributor
timestamp: February 13, 2017, 03:18:28 pm
content: It could be one of that kind, thanks for the hint. I will double check if the ring with the can going over it is isolated from the connector shell. The problem though is i do not get any continuity between any of the terminals. If this is a vacuum diode that probably means the heater is blown.

author: phenol
author_rank: Regular Contributor
timestamp: February 13, 2017, 04:25:44 pm
content: heater degradation was a major issue with the russian vacuum diodes. they were only specified for 1500hrs of operation