Latest Entries »

Continuing on from my previous post where I laser cut a helical antenna for basic radio astronomy, I wanted a way to mount this. Whilst most people that are into these hobbies seem to have  a mast that they can dump another antenna on, I didn’t. Also, I rent so adding a mast wasn’t really a great idea. Also, I’m impatient and have been known to be a bit lazy.  Finally, because I am not receiving terrestrial signals, the antenna does not need a clear view of the horizon, just a clear view of the sky. An idea was thus born.

My logic was along the lines of “take antenna, put on post, attach giant paperweight”. Nice and simple, as long as I could lift said paperweight – it would be portable and easy to work with. Questions then included, what sort of post and what sort of paperweight? The post I wanted to be galvanised so it could handle a considerable time in the outdoors, and the paperweight I wanted to be easy and cheap – hence, premix concrete!

A quick visit to Fyshwick (the home of all things useful industrial in the Canberra region) and I returned with:

  1. ~800mm long, 2″ square, galvanised fence post ($4,  an offcut – check out MetalMart)
  2. a 2″ end cap to make it look swish ($2.50, MetalMart)
  3. a collection of M8 galvanised bolts for reinforcing (about $4, Bunnings)
  4. a 79c plastic bucket ($0.79, Bunnings)
  5. and a bag of premix concrete ($5.50, Bunnings)

Not bad for less than $20.

The bucket, and a drill for scale.

The bucket, and a drill for scale.

The plan was to fill the bucket with concrete, put the post in after  mounting the bolts for reinforcing, let the concrete go off and finally have a portable antenna mount! My calculations based on typical concrete densities were in the ballpark of 24kg for a 10L bucket, so I bought 2 bags just in case. The final product weighs in at about 22kg including the post – pretty good in my opinion, given how much concrete densities vary.

The post and bolts, with holes drilled.

The post and bolts, with holes drilled.

The post with bolts mounted, held in position to demonstrate the "reinforcing".

The post with bolts mounted, held in position to demonstrate the “reinforcing”.

Anyway, I’m happy with the results – I now need to mount the antenna and start looking for a signal!

The post in place, professionally supported and awaiting the concrete to harden.

The post in place, professionally supported and awaiting the concrete to harden.

Finally, a photo of the finished product:

The finished product, awaiting antenna.

The finished product, awaiting antenna.

Just a quick note to say that I have recently publicly launched the website for an Open Source Hardware project that I am currently working on.

It’s called OpenMCA and is an OSHW Mulit Channel Analyser for spectroscopy work. If your interested, please see:

Thanks for looking!

The process for generating fabrication files is the same for nearly all Chinese fab services in my experience, and I just wanted to share some of the configuration settings that I use in Altium, hopefully easing the process for others.

Altium requires two operations to output the required files for all boards, these settings have been tested exhaustively with Mitch @ Hackvana.

First, the NC Drill File:

Next, the Gerber Files:




Please note: The layers output shows me exporting Mechanical 2, not Mechanial 1. Due to a few problems I generally use Mechanical 2 for board outlines. This file must be renamed prior to zipping. 

After both of these Fabrication Output’s have been run, it is simply a matter of navigating to the output directory, renaming the GM2 file to GM1 if required, selecting the Gerbers and the .TXT drill file and zipping them all together.

If further information is needed, please get in touch and I will add some more details!

Happy Gerbering!

Some of the undertakings demonstrated on this website are dangerous and should not be attempted by unskilled persons.
I take no responsibility for any damage done to persons, property or relationships as a result of this information.
Information is provided on the understanding that it is correct, but without any such warranty.
Any undertakings based on the contents of this site are done so at your own risk.