Tellurometer MRA 301 Teardown - Page 1
Forum section: electronics / testgear

author: TerraHertz
author_rank: Super Contributor
timestamp: October 20, 2019, 08:19:29 am
content: A friend of a friend is clearing out some of his storage spaces. As a result, I've recently been receiving assorted bits of old tech for free. Mostly for disassembly to components, but there are a few particularly splendid gems.These for instance. Before I received them I was told they were 'some kind of microwave dish antennas.' It turns out, they are quite historic microwave beam range finders. Used in long distance geodetic surveys before laser rangefinders existed.I found this online:https://www.xnatmap.org/adnm/docs/1genmap/sturman_wright_ppt.pdfThree of them. Sadly all missing accessories like power cable, batteries, headphones, etc. Worst, they are all missing a module that goes on the battery tray, to take mains power and generate 12V DC. But, they might be workable, if I can find a mating connector for the round mil-style DC power input.Amazingly, they came with a complete operation and service manual, with schematics. Incredible.More good luck: the 'headset' connector is the same as on a GRC-106 military radio, and I have some mating plugs for that.This is a pretty cool windfall. I think. Too bad another current project that I've put a lot of money into, is going terribly wrong atm. Spoils the fun.

author: TerraHertz
author_rank: Super Contributor
timestamp: October 20, 2019, 08:23:26 am
content: When I tried to attach all the pics in the first post, upload hung. And so...

author: TerraHertz
author_rank: Super Contributor
timestamp: October 20, 2019, 08:28:14 am
content: more...I'm glad I have a manual. Without that I'd probably have taken a looong time to figure out by myself that to open the case, you have to remove the frequency tuning knob. Turns out the shaft is part of the klystron unit attached to the antenna case. Also, you don't have to be careful to get the dial angular position right when replacing it. It's very precisely keyed; only goes on the right way.

author: Yansi
author_rank: Super Contributor
timestamp: October 20, 2019, 09:27:36 am
content: Absolutely fascinating!

author: SeanB
author_rank: Super Contributor
timestamp: October 20, 2019, 10:39:03 am
content: Nice units Guy, those plugs are available from RS as a kit, though you can also look on fleabay for circular DIN bayonet cable plugs with sockets, 19 pin variety, as those used will probably be cheaper than the ITT Cannon ones from RS. Just buy some old cable plugs with attached cable and use them instead, used works, though you might also want to have a pin insert extract tool around, as the kits come with a cheap red and white plastic tool which is good for around 100 cycles, and a few crimp or solder pins and sockets.

author: threephase
author_rank: Regular Contributor
timestamp: October 20, 2019, 12:41:49 pm
content: Great bits of kit to take a look at. Thanks for doing the teardown and posting.Kind regards.

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2019, 06:20:34 pm
content: thats not a Vietnam era military perimeter system for jungle motion detection?

author: TerraHertz
author_rank: Super Contributor
timestamp: October 20, 2019, 10:50:45 pm
content: Quote from: coppercone2 on October 20, 2019, 06:20:34 pmHa. If there was no other information that could be a candidate guess.But read the history of the series, in that link I posted.

author: ozcar
author_rank: Frequent Contributor
timestamp: October 20, 2019, 11:46:42 pm
content: The developer of these is perhaps better known for the “Wadley loop”, mentioned in a few threads here in the past, and also in this:http://worldphaco.com/uploads/THE_AMAZING_BARLOW_WADLEY_XCR-30.pdfI have an XCR-30 that was out of action for many years. I got it going earlier this year, but could not get the KHz dial to track as well as I would have liked.

author: coppercone2
author_rank: Super Contributor
timestamp: October 21, 2019, 12:36:18 am
content: Quote from: TerraHertz on October 20, 2019, 10:50:45 pmthere is/was a youtube video on one of those old govt film channels about that kind of device, it looks SUSPICIOUSLY similar but I last watched the video in like 2015. something along the lines of how to secure your firebase or whatever