Aeronetworks sro - Airborne Linux

After several years wandering in the Arabian desert, we are heading home to Canada, via Europe.  Thanks to Covid19 we cannot travel as easily as we want now, but with the shift in location, my hobbies can shift to something more green and less dusty (!?).  At long last, my Slovak permanent resident visa application is in progress with the Foreigner Police. Since I'm an ex-army officer, I sometimes enjoy making a big noise with guns and other toys and have the bad hearing and tinnitus to show for it.   The tinnitus is thanks to Oerlikon Contraves 35 mm AA guns and radars - very noisy things with a high firing rate and lots of fun on a large gun range. Three double barrel guns, firing at an airborne target at hundreds of rounds per second, is the ultimate in skeet shooting.  I was workshop officer of a maintenance facility for a while and since then I worked with helicopters...  Ear muffs are for sissies right? RIGHT!?  - A bit too late now... The road less traveled may be more fun

Take out the trash, don't bring it home. There are always a small number of people who go out of their way to annoy everyone else.  The result is that state parks, lakes and beaches have much in common with the internet: There is a ton of trash everywhere you go. You could install an advertisement blocker on your web browser, but those things are usually also spyware in their own way, just less so, than an unprotected network. A Macintosh is a UNIX machine and it is actually very easy to block most trash on the internet.  Download one of the big hosts files that enumerate most trash sites and save it as file  /etc/hosts Here is a good one, provided by a kind soul: https://someonewhocares.org/hosts/zero/hosts Instructions and explanations are in there if you are still a bit helpless about this. It contains lists like this: 0.0.0.0 track.msadcenter.afgz.com 0.0.0.0 track.msadcenter.ajfy.com 0.0.0.0 track.msadcenter.ama.com 0.0.0.0 track.msadcenter.bfy.com 0.0.0.0 track.msadcenter.bvp

I have been playing with the SATNOGS earth observation satellite system for a few years, but since I am still living in the desert, the climate is against outdoor activities, so its been a bit low key. To work on an antenna on the roof, requires a hat, black sunglasses, a wet T-shirt, a wet towel, a litre of water and a big black umbrella and after that I'm broiled for the day... The few times I tried to download a weather picture, it actually worked, despite having seemingly more noise than signal.  An RTL-SDR  or HackRF One receiver really needs to have a low noise RF preamplifier for best results.  There are several solid state, one transistor preamp kits available that one can buy and build in an evening and stick on the antenna cable, but why do something the easy way, if one can do it the hard way? I recently made a 'simple' (!?) power supply for a Magic Eye cathode ray tube VU meter and the same power supply circuit can be used for a one valve RF receive amplifier

I recently obtained an ancient Rusky GI-7b microwave C-band triode.  Packed in an innocent looking styrofoam container (I didn't know they had styrofoam in the bronze age - maybe that is how they floated the pyramid stones down the Nile!), it is quite a monster: GI-7b Radar Amplifier Triode This is a radar amplifier tube designed to operate while pulsing at up to 9 kV and 3 GHz. To digress a bit, contrary to common perception, there are still lots of microwave electron tubes in use,  for example microwave ovens, radars, medical diagnostic equipment and satellites .  Travelling Wave Tubes are popular in satellite transmitters, because they are very efficient, very rugged and small. TWT amplifiers have been manufactured by the likes of Honeywell, Thales and others for over half a century - the frequency band just keeps going up and they now operate in the Ka band :  https://aerospace.honeywell.com/en/learn/products/satellite-communications/traveling-wave-tube-amplifiers What I would

Tinker, Tailor, Soldier, Sailor I like to tinker with old fashioned thermionic valve circuitry - tubes, for the 'Merrykins.  It is strangely crude and simple and they make a friendly orange glow in the evening.  However, powering the things is hard, due to the high voltages that are required to overcome the vacuum. The below picture shows how I build these toys.  It happens on the fly.  This is a hobby, so I don't kill myself with design calculations.  The tag strips enable experimentation to adjust things till it works properly.  The VU Meter even has a little transistor in there - sheer desperation! Transformerless Valve Power Supply One can use transformers, but they are big, heavy and expensive and shipping hunks of metal around the world make it even more so.  It makes sense to use transformers if you build a high power circuit with multiple valves, such as a guitar amplifier, but a small circuit with only one or two valves presents a problem.   For a small fun display pro

A Formal Bow Tie Event I have made a few PCB antennas and the Yagis worked well, but they were very narrow band.  So I tried to improve that by making the elements conical - or in this case, since it is 2D PCB antenna, triangular. I think it is a fairly unique idea and I certainly haven't seen a picture of a PCB antenna like this before.  The Driven element and first director are flared to 3 mm (since there is no more space) and the Reflector and other Directors are flared to 10 mm. Wide Band Yagi with Unbalanced Co-ax Feed I'll see what happens once the conformal coating dried and I hooked up a cable. It is the same design I used before - I just flared the elements and left out the last 2 directors: This way I can compare the two antennas with each other.  I didn't bother to simulate it - I just went ahead and machined it to see what happens. Antenna Gain Initial tests showed that the gain is about 5 dBi which is typical for a 5 element Yagi and the bandwidth of the new an

Clamped Up I needed a little clamp, but we were in Covid19 lock down.  So I made one.  No transistors, no batteries, no thermionic valves, no flashing neon bulbs! There are many complicated ways to make a bar clamp, but I prefer the simple way.  A picture is worth a thousand words: Mini Bar Clamp It can't be simpler: One 6 mm dowel rod One 6 x 80 mm bolt One 1" nail Ten popsicle sticks Glue Yup - ten popsicle sticks glued together, made a small piece of plywood, that I could cut up for the clamp jaws.  You can use the exact same method to make a big bar clamp.  You don't need a super long lead screw, just a long bolt and a whole lot of little holes to adjust the other end of the clamp.  Scale it up as required for size and strength. How do I keep the movable jaw in place?  Some funny putty (Press Stick) in a hole.  It churns around in there and keeps the block from falling off the end of the bolt - a little piece of rubber will also do.  The best wa

While playing with my milling machine and little microwave PCB Yagi antennas, I wondered about increasing the bandwidth and still getting directional gain.  A Log-Periodic antenna looks almost exactly, but not quite unlike a Yagi... Practice is the best of all instructors -- Publius Syrus On a Log-Periodic, all the elements are driven, but each dipole is reversed by 180 degrees.  To make it on a single sided PCB, will require some links to wire up the dipoles.  I added a BNC connector and thin equilength coax to the feed points of the antennas. Stacked Log-Periodic 5GHz To reduce the amount of copper that needs to be milled out, I cut the board close to the radiators.  The bar at the back is for mounting and also serves as a reflective ground plane.  A log-periodic antenna is surprisingly compact and a little 5 dipole antenna will have a gain of about 3 dBi.   By carefully stacking two of them 0.75 Lambda1 centre to centre (54 mm), one should get another 2 to 3 dB of gain