KK6MRI

A friend of mine did not know where the septic tank in their home was. I’ve figured out that this could be a fun opportunity for radio direction finding. A while back I bought several super cheap 433MHz OOK transmitters. They are about $1-$2 each -- not too much for literally throwing something down the drain. 

I soldered a small LiPo battery, connecting both VCC and data to the 3.3V+ of the batter, having the device on transmit mode all the time. I also soldered a 10cm wire to the antenna port. 

To keep everything waterproof, I put the setup in a small bag -- and sent it down the toilette with the help of my assistant Alan!

It took a few tries, but the package was drained and started flowing towards the tank. For tracking I used my new IC-705, which has a nice waterfall plot on the screen, so I can see the peak. For antenna, I used the Arrow. 

It was nice seeing how the frequency of the transmitter changes as it is loaded by the water-- but then stabilizing nicely once it set still (consecutive toilette flushing would shift the frequency a little bit!).  Using this setup we were able to identify the location of the tank, which ended up underneath the deck!

With a simple setup of a Wouxun KG-UV8D+ (260g), DJI Mavic 2, and a 3M Dual lock velcro, I am able to make a crossband repeater, which can connect me to far away places I can’t reach from the ground. The drone can carry the repeater for about 17min. 

Using this, I can hit WA6ZTY (Berkeley space science lab) repeater from Moraga  (east of the hills)

I found that it was important to put the antenna at the back of the drone, rather than the front. When I put it in the front, the gimbal experienced interference, and started going nuts! Moving the radio to go over the battery also helps with keeping the GPS reception. 

This flying repeater is not cheap. Drone ~$1600 + Radio ~$150 + Velcro $17

** Word of caution: Don’t violate FCC and FAA rules. Don’t perform this if you don’t know what you are doing. I take no responsibility for any damage or injury resulting from someone trying to reproduce this setup. 

*** Before flying high, test your setup! Make sure the radio does not interfere with the drone. You don’t want the drone to go crazy high above. 

The radio is quite heavy (260gr)

I launched 3 balloons so far, filled with 80% Helium-air composition. These balloons reached a height of 24000′ (or 7KM). I wanted to see if using pure (at lease almost) Hydrogen gas may help reach a higher elevation.  (answer: Yes it did. As of 4pm 03/022 Pst Balloon is at 29,169′)

The Balloon name is KK6MRI-11 -- follow on: https://aprs.fi/#!mt=roadmap&z=10&call=a%2FKK6MRI-11&timerange=604800&tail=604800

** Disclaimer -- doing this without precautions is DANGEROUS. Hydrogen gas is highly flammable and explosive. Sodium hydroxide is also dangerous and can cause chemical burns. Do not perform this setup if you don’t know what you are doing. The author takes no responsibility for anyone attempting to reproduce this. 

To make Hydrogen, I used a Sodium hydroxide (NaOH) solution in a glass water bottle. I used about 5 spoons of NaOH crystals in about 1 liter.  When you drop Aluminum foil into the solution, it reacts by releasing H2.

Using thermoplastic (Instamorph) I made a cap with nozzle connected to a tube. The tube goes through a PVC chamber filled with Calcium silicate for absorbing the moisture out of the Hydrogen. Then, through a tube into a 36″ Mylar Balloon. 

Since the reaction is very exothermic, I put the bottle inside a bucket of cold water to regulate the temperature. 

Below is a photo of the setup :

Here’s a video showing the reaction and setup:

Here’s the gas burning:

Here’s the balloon, showing 15gr lift of a 17gr load. 

and here’s the balloon with the tracker

Hi all, Balloon link: https://tracker.habhub.org/#!mt=roadmap&mz=2&qm=All&mc=26.66531,-46.96101&q=!RS_*;nu6xb-11 The balloon spent its night traveling north east on an arch-path towards Portugal and Spain. It is traveling at a speed of 60-70Mph, and according to the weather maps is riding the lower part of the jet stream — hence the speed. Overnight it likely hit land around the city of Lisbon taking a south east turn towards Malaga. The Balloon pope up on the maps last night at 12:23am PST (8:23 UTC) just 70 miles north east of Malaga, Spain.  The balloon then kept a mostly south east path at an altitude of 24,000’ and 60+Mph.  One hour later it crossed into the Mediterranean Sea, 60 miles east of Malaga. We were able to monitor it for another 30 or so minutes over the sea. The last packet was received around 2am PST 1/3 of the way between Spain and Morocco. So — where will It go to? To answer this, we can get help from NOAA, the National Oceanic and Atmospheric Administration. NOAA. Is a scientific agency within the department of  commerce. From Wikipedia: NOAA focuses on the conditions of the oceans, major waterways, and the atmosphere. NOAA warns of dangerous weather, charts seas, guides the use and protection of ocean and coastal resources, and conducts research to provide understanding and improve stewardship of the environment. (https://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administration) As part of its activities, NOAA collects atmospheric data, and runs prediction models.  It also makes its models and data available for amateurs like us to run! In particular, the HYSPLIT model is very useful to predict the path that the balloon may take.  HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) is used to compute air parcel trajectories and deposition or dispersion of atmospheric pollutants. NOAA has a web interface to enter starting possible positions and times, and predicting the paths these parcel of air would go to.(https://www.ready.noaa.gov/hypub-bin/trajtype.pl) The attached image shows prediction paths for our balloon. Each color represent a possible path (based on perturbations), each dot represent an hour. Our balloon, according to this Map is now in Algeria, will cross to Libya and then take a path along the Mediterranean Sea and intersect land with either north Israel, or Lebanon.  The downside of this path, is that there are no APRS base stations along the way. The first ones will be either in Israel, Cyprus, or Lebanon. Unfortunately, the balloon will cross these at night time (about 28 hours from now). The slowest predicted path may result in the balloon transmitting over. Damascus into a Lebanese or  Israeli station.  Indecently, one of the paths crosses over my home in Israel (what are the chances!). So, unless we hear from the balloon in the Middle East, we won’t hear from it for a while. In 72 hours the balloon is projected to be in north India. It may pass New Delhi or cross the Himalayas from Nepal to Tibet.  Since the mountains there are over 7200m, I am not sure if the balloon will go over. The next places where there are APRS stations are in  China, South Korea and Japan. I’m hopeful that we will. Hear from it again within. 5-6 days. Cross your fingers. For a beautiful animation of the winds at different heights you can go to: https://www.camarilloweather.com/wxglobalwind.phpYou can press and drag the figures to rotate the planet. The relevant maps are the 11,500’ and the 35,000’. Our balloon is at 24000’, and gets slightly less wind speed, but similar direction as the 35,000’ one. One last thing…. Ham radio operators often finish a QSO — or a contact with the number 73, which means — best regards.  The reason for this has interesting history and is related to early form of signal compression. Signal (audio, text, image, video) compression is the essence of our modern life technology. It enables us to send, store and communicate digital media.  The first (I think) form of compression used for communication is in fact the Morse Code. Morse code is made out of a series of dots (.) and dashes (-) which code letters, words and sentences.  A dot is the smallest unit of time, a dash is 3 times longer. Inter element gap within a character is one unit (dot) long, between letters is 3 units long, and between words is seven times long.  In order to save time — Morse designed his code by counting the frequency of letters in the English language in a New-York Times page, and assigned the dots and dashes such that letters that occur more frequently will have shorter codes, and those less frequent will have longer. For example, the most common letter in the English Language is ‘e’ which is a assigned the code dot “." — only one unit long. The least frequent is ‘Q’, which is assigned the code “- - - . -“ — 16 time units long!. So what is 73????  In the early days of wired telegraph, telegraphers created the “wire signal”, which is a brevity code to save more time and cost when sending long messages. The well known 92-code was adopted by Western Union in 1859. The code uses numbers to represent long sentences. For example, the code 1 = “wait a minute”, 2=“Very important” and 73=“Best regards”.  This is a form of higher-order statistics entropy compression! Hope you all of a wonderful thanksgiving. 73, — Miki

Hi —

Have you ever wondered where escaping party balloons go to? Well, ham radio can help figure this out. Yesterday morning the students of EE84-hands on ham radio class we launched a balloon equipped with a transponder and GPS+solar cells+super capacitors. The transponder only works during the day, and leverages the Automatic Positioning and Reporting System (APRS) base stations infrastructure that amateur radio operators have set up throughout the world. The payload is 18gr and is carried by two party balloons.

As of this afternoon, the balloon went sleeping on the border between Idaho and Wyoming, just south of the Tetons!

Hopefully it will wake up tomorrow further east.

You can track it at:  https://aprs.fi/#!mt=roadmap&z=8&call=a%2FNU6XB-11&timerange=604800&tail=604800

— Miki

As part of my amateur radio class at UC Berkeley, we launched a small party. balloon filled with Helium and equipped with an APRS transmitter.  We pretty much followed the instructions at: https://github.com/lightaprs/LightAPRS-W-1.0/wiki/Tips-&-Tricks-for-Pico-Balloons to the letter.  There’s reddit thread: https://www.reddit.com/r/amateurradio/comments/dxed26/the_ham_radio_class_at_our_school_launched_a/?sort=old

There’s a twitter post: https://twitter.com/sm313/status/1195030447417221120

There’s a facebook thread:  https://www.facebook.com/groups/12699105116/permalink/10162479862705117/

Just ordered and got my nano VNA. I can not believe that you can get such a device for so little. Really fantastic.

S21 of a high pass filter and S11 of a dual band antenna.

I recently got a Wouxun KG-UV8D+. This radio has cross-band capability. My aim was to lift it up using my DJI Spark drone to make long distance contacts, or hit distant repeater that I can’t usually hit from my home. Unfortunately the radio as is, is too heavy.  Looking on-line, it looks like the DJI Spark can lift about 150gr. 

So, I stripped down the radio, removing all plastics and battery, and replacing the antenna with a smaller one. For power I used two small 300mAh LiPo batteries connected in series. 

My APRS station is back on-line. 

I use the HobbyPCB RS-UV3 for the radio, RaspberryPi 3 with Direwolf for the TNC and a USB audio and CP2102 USB to TTL for connecting them.

I also use an RM-Italy LA144 amplifier to get about 20W out. 

I’ve been in on sabbatical in Israel at the Weizmann Institute of Science since August. I’ve been lightly operating as 4Z1ML my new Israeli call sign. We live in an apartment on campus, so space for antenna is a problem. In the beginning I was using my buddy stick antenna on 15m and 20m, and sometimes the alexloop on 40m.  Since propagation on 20m has not been great at night, I decided to put a fixed 40m dipole in our porch. 

The porch is about 8m long, so a full dipole is not possible. One evening, I was bored enough and took some copper wire, two water bottles. I coiled the wire around the bottles to make a loading coil. Connected the wires to the base of the buddy stick plate and vuala! got a nice dipole! 

To my surprise, the first time I measured it, I saw that I the resonance was at ~7.400 MHz. Only 330KHz above my desired JT65/9 frequency. Instead of playing with wire lengths, I found a nice trick to get it down to the right frequency. I added some water to the water bottles, and found that the additional dielectric constant within the coil was enough to get it right down to the right frequency!

Here’s a miniVNA trace of the dipole on 7.050MHz

and here’s another one after poring out a bit of water to move it to 7.076MHz

Here are spots received over 2 hours:

and here are spots other received:

Successful APRS to twitter demo at Cal. Used Baofeng handheld, Arrow Yagi and a custom python code as a modem

http://www.arrl.org/news/uc-berkeley-trains-tests-hundreds-of-new-hams