element14 Community
element14 Community
    Register Log In
  • Site
  • Search
  • Log In Register
  • Members
    Members
    • Benefits of Membership
    • Achievement Levels
    • Members Area
    • Personal Blogs
    • Feedback and Support
    • What's New on element14
  • Learn
    Learn
    • Learning Center
    • eBooks
    • STEM Academy
    • Webinars, Training and Events
    • Learning Groups
  • Technologies
    Technologies
    • 3D Printing
    • Experts & Guidance
    • FPGA
    • Industrial Automation
    • Internet of Things
    • Power & Energy
    • Sensors
    • Technology Groups
  • Challenges & Projects
    Challenges & Projects
    • Design Challenges
    • element14 presents
    • Project14
    • Arduino Projects
    • Raspberry Pi Projects
    • Project Groups
  • Products
    Products
    • Arduino
    • Dev Tools
    • Manufacturers
    • Raspberry Pi
    • RoadTests & Reviews
    • Avnet Boards Community
    • Product Groups
  • Store
    Store
    • Visit Your Store
    • 'Choose another store...'
      • Europe
      •  Austria (German)
      •  Belgium (Dutch, French)
      •  Bulgaria (Bulgarian)
      •  Czech Republic (Czech)
      •  Denmark (Danish)
      •  Estonia (Estonian)
      •  Finland (Finnish)
      •  France (French)
      •  Germany (German)
      •  Hungary (Hungarian)
      •  Ireland
      •  Israel
      •  Italy (Italian)
      •  Latvia (Latvian)
      •  
      •  Lithuania (Lithuanian)
      •  Netherlands (Dutch)
      •  Norway (Norwegian)
      •  Poland (Polish)
      •  Portugal (Portuguese)
      •  Romania (Romanian)
      •  Russia (Russian)
      •  Slovakia (Slovak)
      •  Slovenia (Slovenian)
      •  Spain (Spanish)
      •  Sweden (Swedish)
      •  Switzerland(German, French)
      •  Turkey (Turkish)
      •  United Kingdom
      • Asia Pacific
      •  Australia
      •  China
      •  Hong Kong
      •  India
      •  Korea (Korean)
      •  Malaysia
      •  New Zealand
      •  Philippines
      •  Singapore
      •  Taiwan
      •  Thailand (Thai)
      • Americas
      •  Brazil (Portuguese)
      •  Canada
      •  Mexico (Spanish)
      •  United States
      Can't find the country/region you're looking for? Visit our export site or find a local distributor.
  • Translate
  • Profile
Open Source Hardware
  • Technologies
  • More
Open Source Hardware
Blog Making Mini-Circuits style Tiny Metal Boxes - RF Module Enclosures
  • Blog
  • Forum
  • Documents
  • Events
  • Polls
  • Members
  • Mentions
  • Sub-Groups
  • Tags
  • More
  • Cancel
  • New
Open Source Hardware requires membership for participation - click to join
Blog Post Actions
  • Subscribe by email
  • More
  • Cancel
  • Share
  • Subscribe by email
  • More
  • Cancel
Group Actions
  • Group RSS
  • More
  • Cancel
Engagement
  • Author Author: shabaz
  • Date Created: 7 Dec 2018 4:32 AM Date Created
  • Views 3301 views
  • Likes 12 likes
  • Comments 11 comments
  • minicircuits
  • rf enclosure
  • hybrid_coupler
  • power_combiner
  • enclosure
  • enclosures
  • power_splitter
  • mini-circuits
Related
Recommended

Making Mini-Circuits style Tiny Metal Boxes - RF Module Enclosures

shabaz
shabaz
7 Dec 2018

Introduction

There are some really nice small enclosures that are incorporated into products sold by Mini-Circuits and others. They are very cool because their surfaces are perfectly perpendicular to each other, with no draft angle. This makes them perfect for joining modules together a bit like plumbing, and quick and easy connector alignment.

 

I didn’t know of any low-cost source of them (I could find low-cost angled sides, and really expensive ones with perpendicular sides but not low-cost), so I tried to make my own. This short blog post documents the method I attempted! The end result is physically larger, and won’t have the excellent performance of Mini-Circuits products, but could be acceptable for home use.

Apologies for the poor photo quality with some of the pics further below, some were taken with a mobile phone.

 

The technique could be used for non-RF circuits too. It all hinges around aluminium section, and a bit of metalwork that doesn't need many tools. A vice, hacksaw, file, electric drill, bits, 3mm hand tap3mm hand tap, and countersink bitcountersink bit is pretty much all that is required. An electric saw and disc sander will help though.

image

 

Making It

Take a length of box-section i.e. square-section extruded aluminium, and chop it to the right size (either with a hacksaw, or maybe a machine tool, but avoid a table saw - is really dangerous with alu box section!). Afterwards file it. That forms the body of the enclosure, and holes can be drilled for any RF connectors as required.

 

The photo shows my PCB too – just a double-sided copper-clad board, hand-cut/filed.

image

 

Next, for the end plates, I used 4mm thick aluminium sheet, cut and again filed. Thinner sheet could be used too.

 

If you want to, it could be possible to remove some thickness along the circumference on one side, to make the end plate pluggable onto the box-section. That’s not that easy to do however, without some machine tools.

 

Next, make some holes for screws (countersink them if you wish) on one end plate. For the other end plate the holes need to be smaller, and then tapped (I use a hand tap).

 

Drill holes on the sides of the extrusion for the RF connectors, and file, and optionally sand and polish everything, and voila, all of the metalwork is done!

image

 

For the insides, you could use copper-clad board cut to size, or a custom PCB. In the photo above, I chose to permanently solder the PCB to the nuts holding the SMA connector (easy to do with a soldering iron but needs a 3mm bit or larger, and 60W or more power ideally. This 90W model could be suitable: UKUK / EUEU / USUS). The SMA connectors were bolted on first, and then the nuts were soldered. There are star washers, to try to bite into the aluminium.

In future I may re-visit this soldered-nut method, but for now I went with it for my 5-200MHz intended use-case.

 

For the ground plane, I drilled lots of holes and soldered wire clippings through them to connect the top and bottom copper layers. For non-ground-plane connections, the drilled holes were given copper clearance with the countersink bit.

 

The wiring from the circuit was attached using short lengths of 30AWG kynar wire. This isn’t ideal, but I didn’t have time to design a PCB and get it made.

image

 

This is the underside, you can see the wiring here:

image

 

 

Here’s another example, where no PCB was used. I just soldered the metal can of the circuit (it was a filter) to the body of the connectors, and then made the rest of the connections using short lengths of enamelled copper wire. I’ve not made the end plates yet.

image

 

Here is the underside of the finished module, compared with the Mini-Circuits one. No real difference.

image

 

Using It

Afterwards, I just printed a design on paper and glued it onto the front. Not perfect, but it will do for now!

image

 

Here it is in use, it is being used in a ‘power splitter’ mode as wired in the photo above, converting a 20MHz input signal at 0dBm at the port marked 'J', into two approx -3dBm outputs (there will be some loss) that are 180 degrees out-of-phase with each other. You need same-length SMA cables for this, otherwise the phase will be noticeably wrong:

image

 

It would be interesting to see other people's custom enclosures too. Laser-cutters and 3D printers are definitely making life easier! Also, has anyone explored spraying an electrical screen to the insides of plastic?

 

Thanks for reading!

  • Sign in to reply

Top Comments

  • shabaz
    shabaz over 4 years ago in reply to 14rhb +5
    Hi Rod, Thanks! You're right, the sander helped here. Actually it helps loads all the time, rather than just for finishing, it can be used for shaping even badly misshapen things square really quickly…
  • Fred27
    Fred27 over 4 years ago +4
    Great work. There appears to be no difference in quality between the home-made and ready-made versions in that first photo.
  • luislabmo
    luislabmo over 4 years ago +4
    Hi Shabaz Looking really good!. How much for a batch of 1000 hand-made ? and the lead times ? Luis
  • Problemchild
    Problemchild over 4 years ago

    I used a commercial one from Ebay to do a similar job  only a couple of quit but these are better especially if you want several the same or the next size up from the tiny ones I got. What would be handy is a source of the little screened cans they use for the module them sleeves. They look pressed,  I m sure it would be possible to repurpose a small car part or such for this job!!

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • More
    • Cancel
  • 14rhb
    14rhb over 4 years ago in reply to shabaz

    Great info, and thank you for the links.

     

    You could remake the guide using some of that aluminium box and plate you have (or something similar) ? I agree that these are usually quite safe: we used a larger version in school woodwork (which was a long time ago) and I cannot recall any accidents there apart from plenty of smoke from work pieces being eagerly rammed into the disc. Thanks for including the photo, now I really want to buy one image

     

    Rod

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • More
    • Cancel
  • shabaz
    shabaz over 4 years ago in reply to 14rhb

    Hi Rod,

     

    Thanks!

    You're right, the sander helped here. Actually it helps loads all the time, rather than just for finishing, it can be used for shaping even badly misshapen things square really quickly, So if I cut things inaccurately, sometimes I'll just let the disc sander sort it all out. Surprisingly, the disc doesn't wear out much either. I only replaced the sanding sheet once in two years : )

    I use it for aluminium, wood, and plastic, although of course plastic needs a slow speed, to prevent melting. It worked really well on the aluminium section, except its uncomfortable holding because of the heat conductivity : )

    It squared it enough to make sure the end plate sits perfectly, with no gaps.

    Also it's great that the sander is a 'safe' tool (as safe as any electric tool could get I guess!) so as long as I've got glasses on, there's not much that can go wrong. The 5" size sander size is not underpowered for these tasks, nor too overpowered.

    I used 40mm section (although it measures closer to 38mm) from here: https://www.ebay.co.uk/itm/Aluminium-Square-Box-Section-Tube-1-2-3-4-1-1-1-4-1-1-2-2-End-Caps/271229638209?hash=item3f26…

    but they have larger sizes too.

    The end plates were from a length of bar: https://www.ebay.co.uk/itm/Aluminium-Flat-Bar-20-25-30-40-50-80-100-150mm-wide-Various-Length-and-thickness/271802672656…

    And the bolts: https://www.ebay.co.uk/itm/M3-M4-M5-M6-M8-A2-STAINLESS-STEEL-COUNTERSUNK-BOLTS-CSK-ALLEN-SOCKET-SCREWS-7991/111284266897…

    Photo of the Proxxon sander.. the table and angle is pretty awful. The angle is plastic, with aluminium slider, which inevitably gets bent and then doesn't slide left/right very well at all, it's always sticking. : ( It's a shame, because the rest of it is really nice.

    image

    • Cancel
    • Vote Up +5 Vote Down
    • Sign in to reply
    • More
    • Cancel
  • shabaz
    shabaz over 4 years ago in reply to genebren

    Hi Gene,

     

    That's really interesting!! If I had an internal frame 3D printed, then I could rely on EMI gasket to make a nice seal too... currently I can't do that easily.

    Also, another use would be for creating a jig to drill the holes for the connectors accurately, rather than the current time consuming marking up manually.

    • Cancel
    • Vote Up +2 Vote Down
    • Sign in to reply
    • More
    • Cancel
  • luislabmo
    luislabmo over 4 years ago in reply to genebren

    I think this is an excellent idea.

     

    Luis

    • Cancel
    • Vote Up +3 Vote Down
    • Sign in to reply
    • More
    • Cancel
>
element14 Community

element14 is the first online community specifically for engineers. Connect with your peers and get expert answers to your questions.

  • Members
  • Learn
  • Technologies
  • Challenges & Projects
  • Products
  • Store
  • About Us
  • Feedback & Support
  • FAQs
  • Terms of Use
  • Privacy Policy
  • Legal and Copyright Notices
  • Sitemap
  • Cookies

An Avnet Company © 2023 Premier Farnell Limited. All Rights Reserved.

Premier Farnell Ltd, registered in England and Wales (no 00876412), registered office: Farnell House, Forge Lane, Leeds LS12 2NE.

ICP 备案号 10220084.

Follow element14

  • X
  • Facebook
  • linkedin
  • YouTube