Teardown: defusing Son of MOAB (?) - Page 1
Forum section: electronics / general

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 07:11:17 pm
content: Right.. hows that for a subject line? Got your attention I supposeThing is, last Friday I spent EUR 5 at a local HAMfest for acquiring a fascinating piece of kit. In the meantime I think I found out where it came from,but what exactly its function is remains a bit of a mystery. I hope someone on the EEVblog forum can provide more clues..

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 07:12:29 pm
content: more pics

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 07:13:56 pm
content: more pics

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 07:14:57 pm
content: more pics

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 07:22:17 pm
content: More pics.And some analysis.Obviously this is something that makes heavy use of (most likely high power) RF energy. Robust pure copper plumbing, 15kV rated capacitors,a bi-directional coupler of very substantial construction etc. It is tunable using the glass-fibre reinforced (?) threaded rod.Feeding the directional's coupler part# into Google brings me to an MRI unit, 1.5T.But how this Son of MOAB cilinder fits in the grander scheme of things I still do not know.Any takers?Wilko

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 07:30:22 pm
content: http://unitedrf.com/product-repair/mri-rf-dc/eto-astex-mks/is where I found the part# of the bi-directional coupler

author: xrunner
author_rank: Super Contributor
timestamp: May 01, 2017, 07:32:57 pm
content: Is it a Klingon warp drive pre-initialization exciter?

author: Mr.B
author_rank: Unknown
timestamp: May 01, 2017, 07:58:48 pm
content: Quote from: xrunner on May 01, 2017, 07:32:57 pmI doubt it.Definitely of Federation origin.There are no Klingon markings on the PCB.

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 01, 2017, 08:12:04 pm
content: Maybe just me, but I find the pics too small to really see what's going on here

author: wkb
author_rank: Super Contributor
timestamp: May 01, 2017, 09:21:55 pm
content: I kinda (...) dislike the forumsofrware for not doing the rescaling/resizing to its own standards after upload. The full size images it rejects as (way) too bigOK: very quick and dirty fix/hack: please find the full size pictures herehttps://wkb.home.xs4all.nl/SonOfMOAB/

author: AF6LJ
author_rank: Unknown
timestamp: May 01, 2017, 09:38:21 pm
content: Well I know it is not an initiator for a neutron bomb...They have Brundy connectors....Beats the hell out of me.......

author: Bud
author_rank: Super Contributor
timestamp: May 01, 2017, 10:36:55 pm
content: Rf high voltage connector -> dual directional coupler -> pi network -> L network -> output stage trim capacitor of some sort -> output terminal.A heck of RF current must be flowing in those caps/coilsEdit: a directional coupler and matching network, this is what i think it isEdit 2: if you have a VNA you can measure it. Or estimate frequency from coil diameters and cap valuesEdit 3: Magnetic loop antenna coupler ?.Edit 4: Something like this (pic attached)

author: wkb
author_rank: Super Contributor
timestamp: May 02, 2017, 08:52:10 am
content: Neat diagram Bud!C1 is in series with the coax chassis connector. For the rest it looks plausible.Caps are 33pF, all 6 of them. 2 banks of 3 in parallel so 100pF roughly.I'm still guessing something: matcher for MRI coil?It is definitely adjustable, that is a factory / service tech job, so not during operation.Wilko

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 02, 2017, 12:58:02 pm
content: MRI would be reasonable, as they need pulsed RF excitation.Coupling I would think would be to an inductive "antenna". It's not obvious if the output L and C match would do (but sure, why not?).Tim

author: URFMAN
author_rank: Newbie
timestamp: May 08, 2017, 04:32:54 pm
content: Hello Everyone,The item that is pictured is an tune cavity for a 53-S23A-64 RF amplifier. This runs at 64 Mhz at 25KW. Nice find.Eugene TellesUNITEDRF.com