ad: GNOHF-1

What is the simplest way of building an HF circuit in enclosure?

Discussion in 'General Technical Questions and Answers' started by SV3ORA, Apr 17, 2018.

ad: L-HROutlet
ad: l-rl
ad: Subscribe
ad: MessiPaoloni-1
ad: l-assoc
ad: Left-3
ad: Left-2
ad: L-MFJ
  1. SV3ORA

    SV3ORA Ham Member QRZ Page

    Hello,
    I have in mind these simple HF QRP radios with low components count, built by homebrewers.
    What is the simplest technique that comes into your mind of building such a circuit, so as to store it and use it like a device whenever you need it?

    Some thoughts:
    1. A wooden board with nails for the components and aluminium panel http://www.techlib.com/electronics/graphics/2tranb.jpg This can be made with commonly found components and if components leads are wrapped on the nails, not even a soldering iron is needed. Panel can be used as a heatsink for higher power transmitters, like the one I have built http://qrp.gr/easy40/index.htm
    2. A PCB formed enclosure like this one http://qrp.gr/hf_allband_filter.htm where the whole enclosure is made out of PCB material. The panel is also PCB. This can be more costly since more PCB material and more solder for joints is required. This can be more unhealthy too, lots of copper lots of solder smoke and drilling and cutting of the fiberglass.
    3. A combination of 1 and 2 above, where a wooden-aluminium enclosure is made and the components are soldered onto a piece of PCB material (dead bug) instead of supported by nails.
    4. A tuna-tin enclosure like this one http://www.qsl.net/w2jts/TunaTin2.jpg taken out of used tins but with components soldered directly onto a PCB (dead bug). The tuna tin will possibly be too hard to drill accordingly and can be dangerous on the fingers. Also components cannot be soldered directly onto it, it is not solderable metal.
    5. An Altoids-like enclosure like this one https://vk4jaz.files.wordpress.com/2012/01/p1010013.jpg with the components soldered directly onto the enclosure because it is solderable. Of course you would have to find the enclosure somewhere you cannot build it easily.
    6. I have seen also cardboard enclosures but this is quite unstable mechanically.

    Any other ideas, anything that comes in mind, with some advantages disadvantages described?
    It will be fun to see what people are thinking or have done to enclose their projects into homebrew enclosures.
     
  2. VK2TIL

    VK2TIL Ham Member QRZ Page

    I use diecast boxes with what I call a "chassis"; this is a two-stage Norton amplifier but the technique is applicable to almost any project;

    [​IMG]

    The "chassis" has a base and two endplates, made from PCB stock; I make nuts from brass hex tapped to suit the BNC connectors and soldered to the endplates.

    The circuit can be built, tested & modified on the "chassis" outside the box; assembly and soldering is much easier than working inside the box. When all is satisfactory, the connectors are unsoldered & removed, the "chassis" dropped into the box and the connectors re-inserted and soldered.
     
    WA7PRC, KC8VWM and (deleted member) like this.
  3. SV3ORA

    SV3ORA Ham Member QRZ Page

    This is very good for RF especially VHF and up as there is strong shielding.
    I has thinking more of junk box-made homebrew enclosures/circuit making in my post, so I find a few drawbacks on this approach especially when considering cheap homebrew HF gear.
    These enclosures are not that common in all cities around the world.
    They are of high cost compared to other enclosures, which exponentially increases when size increases.
    It is hard to drill them because they are thick (hand tools are out of discussion).
    They contain some cadmium and lead (as impurities) but let's just not take that into account here.
    I have found them quite dangerous also while drilling on a vertical drill, because they are thick, large diameter drills tend to stuck into the hole causing all shorts of accidents, especially when holding the enclosure with your hand while drilling.

    But thank you and let's consider it number 7 in our list.

    Any other ideas, anyone?
     
    Last edited: Apr 17, 2018
  4. KM3F

    KM3F Ham Member QRZ Page

    Square and Rectangle Electrical boxed and their flat covers in both metal and plastic.
    About as cheap as you can go.
     
  5. W1VT

    W1VT Ham Member QRZ Page

    Die cast boxes have mounting holes that can be used to securely fasten them to a work surface.

    Zak W1VT
     
  6. KL7AJ

    KL7AJ Ham Member QRZ Page

    I'm highly partial to the PCB idea. It's fast, simple, cheap, and doesn't look too ratty. :)
     
  7. K6CLS

    K6CLS Ham Member QRZ Page

    Please, use sharp drill bits, drill pilot holes, and never ever hand hold.

    I still have all 10 fingers and intact skin.

    Oh, and always wear eye protection.
     
  8. VK2TIL

    VK2TIL Ham Member QRZ Page

    Agree.

    Do not hand-hold small parts in a drill press; at the very least, hold with stout pliers/Visegrips etc.

    Also; use a step drill for sheet metal & diecast boxes. Twist drills can & do grab on exit from the hole; they also often form a multi-lobed hole instead of a circular one.

    An old trick to avoid this is to drill through several layers of rag; this creates a round hole.
     
  9. KE0ZU

    KE0ZU Ham Member QRZ Page

    I also use cast boxes and clad "chassis", for all the reasons previously stated. they can be made virtually RF tight if need be, and, they are very sturdy.

    Always be as accurate in your construction as possible, and use sharp tools.
    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Apr 18, 2018
    KB4QAA and W7UUU like this.
  10. VK2TIL

    VK2TIL Ham Member QRZ Page

    Nice work, 0ZU; you seem to think, like me, that a project should both look good and function well.

    If you put PCB-material endplates on the filter, you would have a "chassis"; this allows the filter or other device to be built & tested without the diecast box. It can be very fiddly to work deep inside a box.

    The enclosure rather depends on how fussy the builder is about appearance; many, like the OP, are content with roughly-soldered PCB cases and that is fine, it's just not my way.

    I enjoy the challenges presented by enclosures; they can be greater sometimes than the electronics challenges.

    I've made a few PCB enclosures but they are time-consuming if good appearance is required;

    [​IMG]

    [​IMG]

    Diecast boxes take less time and look good if not better; this is the Norton amp from the outside;

    [​IMG]

    Ebay has these boxes available in Greece for about $10; worthwhile if you value appearance.

    PCB boxes are useful if building an MMIC amplifier on one of the many PCBs available; it allows the box to be fitted to the MMIC PCB to ensure good shielding & grounding.

    I had to combine two techniques to make this dual MMIC, very high gain amplifier stable;

    [​IMG]

    [​IMG]

    It helps to be on the lookout for surplus/hamfest/junkshop cases and store them away for future use;

    This power meter was built into an old intercom case with a sloped front;

    [​IMG]

    whilst this AF voltmeter was built in a case formerly used as a slide-projector controller;

    [​IMG]

    PCB material was used extensively;

    [​IMG]

    As an example of "starting from scratch", I made the case for this attenuator in my modest workshop;

    [​IMG]

    [​IMG]

    I did have to get a local metal shop to fold the 4mm aluminium centre section into a U-section; I'm not equipped for that.

    Otherwise, all my own work; tapping M2 holes requires a steady hand.
     
    WA7PRC likes this.

Share This Page

ad: K6IOK-1