Malahit out in the field

Designing and printing a case

I got a Malachite clone for fathers day 2021

I had been keen on this receiver for a while since I found it on YouTube a year ago. I could never really justify the cost of buying it direct from Russia. I ended up seeing a registered version with all the improvements that some of the clones lacked on eBay. It’s probably a hacked version, I know this now seeing the forums. if you can afford it support the Russian version. if your on a budget eBay or Alliexpress.

I use my Malachite receive just as it was out the box, the PCB and speaker mounted in a milk carton to give good sound for about two weeks. I got to work out what I wanted while using it. The layout drove me crazy, who has the tuning knob on the bottom and they are way to close together.

I designing the enclosure took a while with many hand drawings

Drawing in Fusion 360

As it was the tuning and volume knobs were too close together and the wrong way around. I wanted the speaker out the front for better sound.

I didn’t want the case too big either, good battery life ( I hate flat batteries). I picked a 6000mA battery.

The USB and ear phone socket are too close to the knobs so that has to change.

I wanted my own knobs too as I can’t find anything I like. They will have TPU grips.

Now with some hand drawing and lots of ideas it was time to draw it in Fusion 360

First I measured and drew the PCB as a reference, Once this was done this was my reference. I could designed the other components around the Malachite PCB to fit.

I designing some knobs two types and a kick stand. Well the kick stand will be a version two for the back cover. Maybe a carry handle too. It took quite a few version till I was happy with the design and fit.

I was not happy with how the antenna fit as I wanted a built in telescopic. For now I will leave it as is with the SMA. Playing around with the SMA on the Malachite PCB would upset the higher frequencies. I would need some RF switching that I will design later to switch the telescopic antenna in.

I printed out the front of the case first after triple checking my drawing. Measurements were done on the printed part and it was spot on. The PCB slid in nicely. I had designed landing that the PCB would sit on to make a good ground contact. Next I printed the back lid, my first version that is a simple design.

The inside was then lined with copper tape for shielding. This is copper tape that is used in electric guitars. With out the shield all the data noise would radiate out of the case. It also aids the capacitive touch screen to work.

Because I reconfigured the location of the dials and plugs I needed some PCB’s to be designed. I did this because its much neater and easier to fault find in the future.

The PCB’s were drawn in Autodesk Eagle, Why? Well I use to be a Protel person, my work has the original Eagle program. I never could work out how to draw with it. So I forced my self to learn Eagle too further proof my knowledge for work, hay its also free. It was a painful and slow process but I got there, again YouTube!

The PCB file is exported as a Gerber file, then imported into a program called FlatCAM. This is free too, it converts the files into a usable GRBL for my CNC engraver. Well there it is another two topics to write about in the future, my CNC kit and FlatCam. So you may have notice there is a lot of things to learn in my journey, life isn’t meant to be easy.

The scary part!

I carefully removed the encoders from the Malachite PCB as well as the earphone socket then soldered in PCB headers. Next soldered wires across the power switch. This switch is too small to remove so I left it in place. it was located in them most stupid place.

Wired up the PCB to the header sockets looms and assembled the bits to the enclosure. Measured the continuity of the copper tape shielding to the PCB etc.

When the back lid is put in place the shielding is complete, it’s amazing how the sound changed, the back cover has an air vent for the speaker.

Switched on the Malachite for the first time.

Wow this thing is awesome and way more natural to use in my hands now. With the speaker I have chosen it has a really nice sound, nice base but with good treble.

The screen generates a bit of noise when using the telescopic whip. This can be solved my switching the screen off, a short press of the power button does this, or a long press of the volume knob will switch off the touch screen scanning. Probably why these features were though off. I did have a though off adding a shield behind the screen, another idea was modify the touch screen engine to make the interference less aggressive. It’s not that much of an issue to worry about.

So far I’m loving the receiver, great battery life with the 6000mA battery, will go down to about 50% of 7 hrs of use. The ergonomic of the enclosure suits me for now.

The kick stand and a carry handle or strap would be good, May be some TPU bump stops to protect the radio from drops.

I really think this receiver is worth the money, its so cool not to have to use a PC to have SDR in your hand. it is a really amazing bit of kit. For me to be able to see the signals just brings a new dimension to portable SWL. You end up watching the screen like a tv.

Finding the right eBay purchase
Testing out speaker and battery
Drawing case in Fusion 360
Prusa printing the knobs
raw print with supports not removed
case measures spot on
PCB design on eagle
CNC engraving the PCB’s
test fit the pcbs
Shielding, copper tape inside surfaces
ready to put back on after testing
Its finished. well for now

I have this design on Thingiverse, like the NanoVNA each clone may be a bit different so what I design may not fit another PCB. Tip the LCD screen is attached with double sided tape. Because of this the LCD can be detached and repositioned to get the from cover to fit. I found this out when I was 0.5mm out on the screen location.

Thanks for reading

3 thoughts on “Malachite DSP, making a custom case”

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