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Getting Started, RaspberryPi, APRS, Xastir Part 2

April 20, 2018 Leave a comment

Let’s get our geek on girls.

So you got your RaspberryPi, you installed the OS from your NOOBS SD card or manually, as per Part 1, now what? Well there are lots of great things you can do, but I’m going to help you set up APRS.

You will need

RaspberryPi with operating system installed.

Keyboard and mouse and HDMI screen and HDMI cable

A Terminal Node Controller such as  TNCPi, or a radio with a build in TNC, like the Kenwood TM-D700 series and a suitable cable to connect your TNC to the pi if the TNC is not an add on board, commonly referred to as a hat.

APRS, variously known by a few names is an Automatic Packet Reporting System, commonly used to show locations of objects and for messaging, typically on VHF and UHF but also HF. You can see APRS in action by entering the name of your city into the search box at www.aprs.fi. You can adjust the time span to see movement of the various objects over a span of time. Below is my city of Sydney (VK2) for the previous 24 hours. That moving house is a worry 🙂

Screen Shot 2018-04-21 at 08.55.30.png

APRS can also be used to show and share weather at your location by integrating your APRS with your weather station should you have one. I will explore that topic later.

Here is my weather station on APRS

Screen Shot 2018-04-21 at 08.59.24.png

So let’s get started

Your raspberryPi is turned on, connected to mouse, keyboard and an HDMI screen.

Open up the terminal, remember it is the black icon >_ or use the keystrokes mentioned in Part 1 Cntrl-Alt-T.

Into terminal type the following, one line at a time- ignore lines preceded with #, these are my comments

# You should always update before installing new software

sudo apt-get update

# install the xastir package
# hit ‘Y’ when prompted – it installs lots of dependencies
# so will take some time

sudo apt-get install xastir

# now start X-windows if you’re not already in the graphic user interface

startx

Once you have xastir installed and X running, you will find xastir listed under internet on the newer versions of the OS– alternatively open up a terminal window and start the program by typing xastir.

You will be prompted for your callsign and location etc. – this is fairly self explanatory but the xastir website will be able to help. One thing I will say is that the first thing you’re likely to want is a better map – go Map > Map Chooser, select the four Online/OSM_cloudmade_3.geo maps for Open Streetmap, and deselct the default worldhi.map. It will take a bit of time for the maps to be downloaded but they’re very good. You will also need to know your latitude and longitude in degrees and decimal minutes not degrees minutes and seconds or have a GPS connected as well (more on that later). You can find your lat/lon on Google maps with a right click on your location. You can convert to various d,m,s decimal degrees etc at many conversion sites like https://www.directionsmag.com/site/latlong-converter/

Connecting a Terminal Node Controller (TNC) 

There are many TNCs available but I use a Kenwood TM-D700. It and the D710 have a built in TNC. Follow the radio manual instructions and set the TNC to serial, not KISS.

If you are using another TNC, follow the instructions to connect it to the Pi and to set it to serial TNC mode.

We will explore other TNCs in Part 3.

For those TNCs connected by USB, you will need a cable to connect to the USB port on the Pi. You will definitely need a special programming/serial cable to connect your D700 series radio. Don’t fool around with serial USB converters they will not work, Use this cable if you have a D700 series radio. It is the only one that I have found that works with the Kenwood radios

So let’s get data coming in from our TNC.

First connect your cable to both TNC and Pi. Find the USB port that it is connected to with this command in terminal

dmesg | grep tty

#That | key is hard to find on some keyboards.
#On my Apple keyboard it is on the far right and requires shift. :-).

You should see something like this

Screen Shot 2018-04-21 at 09.33.49

Note the second last line – My FTDI cable is ttyUSB0, yours may be different.

Now go to Xastir  Interface > Interface Control and click ‘Add’. Select ‘Serial TNC’, set /dev/ttyUSB0 as the port or whatever you found yours was with the dmesg command, change the baud rate to 9600 and leave the rest as default for now, although you might want to change tnc-startup.sys for one matching your TNC from the list in /usr/share/xastir/config. Mine is tnc-startupD700.sys

Click ‘OK’ and hopefully, you’ll be able to select your new interface and start it – ‘DOWN’ will change to ‘UP.

For debugging, View > Incoming Data provides some very useful insight into data flowing to and from the TNC or other interfaces.

If you want to receive data from the Internet, add an ‘Internet Server’ interface. You’ll need to get a passcode to match your callsign (google APRS passcode generator for clues,) and find your most convenient aprs host and port. Again, the ‘Incoming Data’ window can help with debugging. My aprs server is first.aprs.net.au. Take a look here for yours http://www.aprs-is.net/aprsservers.aspx

At this point, consult existing XASTIR resources to refine your configuration. Good luck!

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Getting Started RaspberryPi, APRS, Xastir Part 1

April 13, 2018 Leave a comment

Screen Shot 2018-04-14 at 08.42.03.png

This blog post is intended for hams beginning with RaspberryPi, who want a great ham radio project. It was initiated by a query on the YL Op Net a women’s only net that happens 0000 utc Fridays on the ALARA Conference Server.

The first thing you need to do is get yourself a Raspberrypi. If you are brand new to RaspberryPI you may wish to buy all of the bits and pieces you need straight up as that is often the cheapest option, unless you have some stuff laying around, like keyboards and mouse and HDMI monitor or TV. There are some great complete kits on eBay and elsewhere.

While you are at it, why not get the preinstalled operating system on an SD card and save yourself the process of setting up your own SD card. This is a good idea until you get more familiar with the pi. Otherwise you need SD card formatting software and a range of other tools and a fast SD card. The RaspberryPi 3 uses micro SD whereas the earlier models use normal SD cards. The prepackaged OS install is called NOOBS. If you want to go it alone, try this resource for a how to

https://www.raspberrypi.org/documentation/installation/noobs.md

To get started with RaspberryPi, one of the best things you can do is find a likeminded group of people either physically located near you or via social media. Most RaspberryPi’s are initially setup to run a Linux operating system called Raspian. If you have not ever used command line interface or Linux before, it will be very useful to have some help on hand, as it can be daunting initially. The new operating system on the RaspberryPi has a great Graphic User Interface (GUI) but because of the inability to log in as root and for other reasons of convenience, you will do most to your work in the command line. Command line looks like this-

Screen Shot 2018-04-14 at 08.11.05

The above is a great example because one of the first commands you will need to know is sudo. Think of it as “superuser do.” When you log in to a pi as you can see from the above image, you are logged in as pi. eg. pi@raspberrypi. Now the user named pi is not a superuser, not an administrator, probably so we can’t mess things up too much. So if you want to do something like install or remove software or update the system, you have to tell the pi that you wish to do that as a superuser, hence sudo. You will quickly get used to preceding most commands with sudo.

Plug your keyboard and mouse and HDMI cable connected to a screen in and turn the screen on- you can use a television. Put the SD card in the pi and connect the power. There is no on/off switch. I am going to assume you have access to a HDMI cable and a monitor, otherwise you have to run the pi headless which I will describe later. When you get your pi and start it up, if you are using the latest version of the operating system, it will load the GUI. Do not connect power hungry devices to the USB- you will need a powered hub if you do.

You will need to access the command line interface, which you do by opening  the terminal. Click on the black icon with this symbol >_ in the top menu bar or type Ctr+Alt+T.  The very first thing you need to do before you do anything else is update and upgrade the software that is installed. So you will get to use the command line straight up. Later on when you are running headless, you could  copy and paste  from this blog and save some time, but for now, just type the following commands

sudo apt-get update

Then wait for the pi to complete the tasks and select y or yes if asked.  Then type

sudo apt-get upgrade

This one will take quite a bit longer to run and will require interaction.

Now you should be ready to get started with installing Xastir. Bear in mind that this blog will describe using Xastir connected to a Kenwood TM-D700 which has a built in Terminal Node Controller, (TNC) If your radio does not have a built in TNC, you will need to get one. There are a few made especially for the RaspberryPi, like this one.

73

de VK2KIM

 

 

 

 

 

 

Categories: Uncategorized

KRK VXT6 Repair

February 6, 2018 Leave a comment

Some time ago I picked up a powered studio monitor for about $20. The music store was closing down and the speaker had a fault- the tweeter wasn’t working. These studio monitors of this size range in price from about $200 to $400, so I couldn’t pass up the deal, as I was sure I could repair it – one day.

That day finally arrived. I had purchased a spare tweeter which had sat in the parcel unopened for some time. When I unpacked it, you guessed it, it was the wrong part. Given that it had come from the US, the return postage added way too much to the cost of repair, so I decided to repair the existing tweeter.

20180206_134528

There isn’t much to a permanent magnet tweeter, basically the only electrical component in it is a super-fine winding of copper. This usually fails to due physical stress or sometimes an over-voltage or over-current fault. All that is required is to solder the broken wire- easy right? Well the wire is quite a bit thinner than a human hair and enamelled and wound very tightly into a place that is difficult to get to. You got the picture?

20180206_134524

The good story is that after one repair, a subsequent failure and another repair, the speaker works great

 

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Breville 330J Restoration Part 1

January 29, 2018 Leave a comment

I picked up this Australian built radio some time ago. It has sat in a carton in my storage for some time. When restoring Dad’s 1935 Ultimate I wondered if I could get some donor parts from this radio, but when I took a look at the condition of the electronics, I decided to restore it. The electronics are in amazing condition. The radio was produced in the late 1940s, possibly 1948.

27066775_1840903212627293_4071677038937855009_nChassis

I removed the chassis from the wooden case and due to the excellent condition, decided to fire it up without replacing the capacitors. I ran it up on a variac and it came to life, with very low audio. The valve line up according to the markings on the chassis is 5Y3G rectifier, 6J8G Osc/Mixer, 6U3G IF Amp and 6G8G AGC, El3G Audio Amp

27459796_1840903095960638_6219527409611782842_n
5Y3G rectifier socket.

27332373_1840902999293981_817692224466341981_nIF Amp- Actually says 6U3G now that I see the photo
27336788_1840902855960662_8686029314503663033_n
6G8G or 6B8G RF Amp and AGC

27336383_1840902512627363_4451401657496770986_n
EL3G Audio amp

The schematic I have shows a slightly different line up and initially it caused me to be confused. I had confused the audio amp with the mixer. The EL3G that is supposed to be in this set is similar in code to the EK2G on the schematic, but anyway I have now sorted it out.

The EL3G is made of unobtainium so someone had inserted a 6F6G which is much lower gain- this would explain the weak audio. So what I need to do is change the EL3G for a 6V6G and change the bias resistor to reduce current draw. I can test to ensure the control grid voltage is around -12V and all should be good.  Unfortunately audiophiles have pushed the prices of 6V6Gs, for their trendy valve stereos, through the roof…. more soon.

Categories: Vintage Radio

My Dad’s 1935 Ultimate Receiver – Part 2

January 25, 2018 Leave a comment

I returned home to Northern QLD, some 2200 kilometres from where I now live in Sydney, for Christmas 2017. I was working, house sitting and dog sitting, which gave me plenty of time in the evenings and weekends to repair Dad’s radio. Unfortunately some late  received communication meant that I failed to bring my test equipment and tools, so I shipped the radio to Sydney via Greyhound, to be picked up on my return.

Fortunately the radio was unscathed by the bus trip and was promptly placed on my workbench for the investigations to begin. It became immediately clear, that the capacitor I had failed to change had destroyed itself in rather spectacular and gooey fashion and taken out a few other components as it went. An inspection revealed a failed 2A7 mixer and the 57 valve (vacuum tube) had a loose glass envelope. I suspected other damage but could see none.

I replaced the capacitor and ordered replacement valves (tubes). When the tubes arrived I replaced the defective ones, and the rectifier just for kicks. I turned the radio on, the lights glowed, the valves glowed but no sound. hmmmmm. A quick check of voltages found nothing out of the ordinary as far as the mixer and audio amp were concerned.

This made me suspicious that I had an open speaker field coil. A failed coil, either field or in primary, was confirmed by removing the audio amp with the radio on- no click from the speaker. So some further digging around is required…. more in Part 3.

Categories: Vintage Radio

My Dad’s 1935 Ultimate Receiver Part 1

January 23, 2018 Leave a comment

Some time back in 2015 I obtained a 1935 Ultimate AU Receiver. I had just recently restored a 1936 Pilot receiver and was keen to do the same for this radio. What I most liked about the radio was that its “birth year” was the same as my Dad’s. Dad’s 80th birthday was forthcoming and I thought that the radio would make the ultimate present. He and my Mum had been loaned a console radio early in their marriage and I know they loved it and were disappointed to see it return to the owner, many years later.

thumbnail_RL AU 34 pix 2

I set about doing as much restoration as I could before my Dad’s birthday, which was to be soon. Unfortunately it was during the worst part of my life, when my gender disphoria had resulted in serious mental health issues and the loss of all that was dear to me. I rushed to get the radio ready for the birthday celebration while dealing with my own demons. One capacitor proved difficult to obtain- a filter capacitor across the DC output of the rectifier, so I left the original there. I left the radio running for many hours as a test and it worked a treat.

When I presented the radio to my Dad, on the day after his birthday, it immediately failed with a loud pop. I left it with him, with the view to getting back to it “one day.” BTW he loved it.

However my life was about to take a radically different path and it would be some time before I saw the radio and indeed my Dad again…… More in Part 2

Categories: Uncategorized

A Different Project- An Audio Amp

August 26, 2017 2 comments

A friend of mine contacted me to ask if I knew someone who could trouble-shoot her valve driven audio amplifier- of course I said I could. The amplifier is an interesting Chinese brand, a Yaquin MC-100B. It can be used in two different modes Ultra-linear or Triode mode. The amp uses a bunch of valves including 2x 12AX7 a pretty common  amplifier found in everything from guitar amps to radios, used in this case as voltage amplifiers. It also uses 4x 6N8P as drivers and cathode followers and finally 4x KT88 valves in the output stage.

My friend complained that the amp had not worked for nearly 12 months but the filaments on all valves glowed. According to her tests, it had no output at all. She dropped it off and I promised to take a good look at it. Since I was lacking any means to connect any kind of music source to it, I got straight down to visual fault finding- a mistake but only a minor one- it simply cost me some time. I was later to find that when I did connect it to a source it worked, though not perfectly.

I began by removing the bottom plate and visually inspecting all components and PC boards for damage, burns, broken tracks, anything obvious- there was nothing. I then began checking all voltages at the appropriate test points. Beware if you are attempting to do the same. There are some KILLER voltages in here; some over 1000V AC. Beware!

I found all to be within specification. I at this time did not check the bias as I wanted to first confirm the amp had no output at all. I connected my audio signal generator to the audio inputs on the front of the amp (labelled 0.6V). I configured the amp switches appropriately for these inputs and connected some speakers. I immediately heard a pretty good tone, so the amp did have output after all. I confirmed with my friend that she had not just inadvertently had the inputs configured wrong, but she advised she had tested all configurations. hmmmmmm …some testing at her place may be necessary to check that the audio source is not the issue.

Continuing with my testing I noticed that one channel was lower output than the other. I began by checking all bias voltages, finding all of them low but one non-existant. I swapped the suspected KT88 with one of the good ones and the bias voltage returned- indicating a failed tube. I then set about adjusting the bias voltages to 0.55V as specified. Even with one channel low, the amp sounds pretty good.

I instructed my friend to purchase her choice of new KT88 or a matched set of four. This amp is not very sensitive to valve changes, so I would just purchase one. I finished up the repair with fixing the cage over the valves, as it had begun to come apart.

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