News items for tag electronics - Koos van den Hout

2019-11-16 Getting distracted by weird noises and listening to data from car tires 6 days ago
I was tuning across the 70cm amateur band and heard lots of weird noises around 433.92 MHz. Which is logical: that's the ISM band (industrial, scientific and medical) so lots of unlicensed low-power signals there.

That triggered me to update rtl_433 and see what I could receive. The answer after some searching how to build a running version: a lot. Including tire pressure monitoring sensors (TPMS) on a nearby car:

time      : 2019-11-16 15:33:25
model     : Toyota       type      : TPMS          id        : fb8c8bf9
status    : 128          pressure_PSI: 38.500      temperature_C: 6.000
mic       : CRC
There is indeed a Toyota parked across the street. I see three different values for 'id' suggesting that three wheels are 'awake' and reporting tire pressure data about every two minutes. According to eavesdropping the wheels, a close look at TPMS signals the sensors should only activate when the car is going faster than 40 km/h or when a special LF signal is active.

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2019-11-13 More investment in remote HF operation 1 week ago
So the order for the remoterig duo to work on my remote HF operation plans is out the door. I ordered them with HamShop to get Dutch warranty rules.

I also ordered some other stuff from Conrad to be able to get everything cabled correctly. I may have missed something but I hope to have enough to get going and be able to have frontpanel and main radio hardware separated by Internet.

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2019-11-06 Tested and attached wires to the new 12V powersupply 2 weeks ago
Powersupply with wires attached
Powersupply with wires attached
I had time to do some soldering and I tested and wired the 12V server powersupply I bought last Saturday at the "Dag van de Radioamateur" ham convention.

The powersupply that I bought is an HP DPS-800GB A and it already had two wires to make it start up when input voltage is applied. I just soldered thick wires to the output terminals so I can connect it to the HF amplifier. Unlike the previous HP DPS-700 powersupply this one has two builtin fans so it won't overheat.

Time to test it with the HF amplifier is this weekend. I'll test the output power with the current output voltage left as-is. It's currently at 12.2 Volt when no load is applied. There are simple modifications to raise the voltage as described by Server supply DPS-800GB - PA0FRI.

Update: After some testing it's clear there are two problems: the output voltage of this power supply does not get very high before it switches off. About 13 volts. At that voltage the output power of the HF amplifier is limited. And when using the external amplifier I had a lot of problem with the connection between the computer and the radio. As soon as I started transmitting the computer started giving error messages about the communication with the radio.

So back to just the radio and its output power at the moment.

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2019-11-02 I visited the "Dag van de radio amateur" (DvdRA) ham convention 2 weeks ago
Today was the Dag voor de Radioamateur edition 2019, and I went there.

My main todo item was to deliver outgoing qsl cards to the Dutch QSL bureau and pick up the new ones for Region 08. So I walked in with a big shopping bag and after visiting the Dutch QSL bureau market stall I returned to the car right away with a new box full of cards. After that I walked in again and started looking around. I was looking for certain parts I needed recently such as RCA connectors, 2.5 mm stereo jack connectors. I also had some specific things in mind such as a newer high amperage 12V supply because the previous server power supply smoked itself and an antennaswitch and serial connectors for remote HF operation which I found. I found no USBaudio and USBserial interfaces so those will be picked up in the next electronics web order.

I attended a lecture on the QO-100 amateur satellite and the story behind the Patch of the Year antenna co-developed by Remco PA3FYM.

I also met a lot of amateur radio friends, more than I expected!

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2019-09-14 The nanoKeyer morse keyer in its case 2 months ago
The nanoKeyer morsekeyer in case with paddles
The nanoKeyer morsekeyer in case
I found help at the radio club, Kees PA5Z made his metalworking skills available and now the nanoKeyer has a nice case and works fine in it.

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2019-09-06 The morse keyer is working 2 months ago
nanoKeyer morse keyer and morse paddle key
The nanoKeyer and the morse paddle key. Connections to the nanoKeyer from left to right: cw to radio, input from paddle and usb to the computer
After a few hours of thoroughly soldering and checking the results the nanoKeyer is done. I did find an error in my work so I had to get out the desoldering iron to fix it: I put the wrong resistor in one place.

Next step was to get the arduino that is the core of the nanoKeyer tested. There was an arduino nano included with the kit preprogrammed with the nanoKeyer software, but it still needed the print headers soldered: two rows of 15 pins and very secure soldering work. I did put the small tip on my soldering station for this work and used a magnifying glass to check my results. It seemed to work fine but I noticed soon the speed control potentiometer and the menu buttons gave no response. Both those functions use an analog input of the Arduino in the nanoKeyer. I had bought an arduino at a previous radio parts market so I tried that one. This one already had the print headers installed so there was less chance of causing a defect.

That one had to be programmed first, so I dove into getting the Arduino integrated development environment installed. After a few tries it seemed the only way to have working USB communications is to run the whole Arduino IDE as root (using sudo). Not very secure but at least I could continue my work. The right settings were made according to the nanoKeyer Firmware Upload Guide 2 and the Arduino nano I bought myself works fine. The result: sending morse code, changing settings with the menu button all worked fine.

The ultimate step was to get software controlled CW generation working. I soon found Winkey USB works in Linux - OK1RR which has a driver binary (no source unfortunately) which communicates fine with the nanoKeyer. The network UDP protocol is somewhat very binary so I used one of the cwdaemon test programs to get actual morse code sent from the computer.

Now for the (for me) hard part: making the right holes in the case. I'll try to find some help at my radio club.

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2019-09-04 New electronics project: a morse keyer 2 months ago
My learning morse is still ongoing and I'm taking the first steps in generating morse. I decided on a paddle as a first morse key to get the dot/dash (or better: Dit and Dah) timing correct automatically. Opinions on tbe best choice for first morse key differ: some say a straight key is the best, others say a paddle. I'm sticking with the paddle at the moment because I also have a tendency to develop RSI. Telegraph operators were the first profession to have cases of RSI so I hope to avoid that.

I recently bought a paddle: the uniHam UNI-730a which is a nice affordable paddle for a starting morse operator. With the built-in keyer in my Yaesu FT-857 radio it is possible to create good morse code. I use the option to create the morse tone on the radio without transmitting to practise sending morse. I check the results with the Android application Rx Morse.

But, I want to be able to participate in morse contests in the future. For those a cw keyer is necessary that can be controlled both from a paddle (or a straight key) and the computer. I was looking at options when a fellow club member mentioned he had a nanoKeyer morse keyer kit available that he wasn't going to build himself because his radio can do all that work. So I bought the kit from him, including case and I'm soldering the first parts.

Since all parts are through-hole, I am soldering with the components 'hanging' from the board. I want all components to be as close to the printed circuit board as possible so for some things that want to 'fall' I use rubber bands to make them stay close to the board for the first soldering connections. I do avoid warming up the rubber bands, they will probably break and/or burn causing a nasty smell.

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2019-07-20 Going full duplex with amateur satellites, part 14: Switch to FUNcube Dongle Pro+ 4 months ago
FUNcube Dongle Pro+ I saw a radio amateur offering a secondhand FUNcube Dongle Pro+ for a very reasonable price and remembered my work to get into linear satellites and the problems with the input filtering on an rtl-sdr while transmitting. So I checked the specifications for that dongle and saw a lot better filtering.

I decided to go for it and a few mails later the dongle was on the way to my letterbox. Literally, as it fitted in a small package that could be delivered in the letterbox. With tracking, so I received a notification from the package tracker app after the mailman put it in the letterbox.

There is good support for the FUNcube dongle Pro+ in gqrx so I tried that first. It does give some USB errors:
[46918.612090] usb 2-1: new full-speed USB device number 10 using xhci_hcd
[46918.762268] usb 2-1: New USB device found, idVendor=04d8, idProduct=fb31
[46918.762273] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[46918.762276] usb 2-1: Product: FUNcube Dongle V2.0  
[46918.762278] usb 2-1: Manufacturer: Hanlincrest Ltd.         
[46918.797477] usb 2-1: 1:1: cannot get freq at ep 0x81
[46918.803092] hid-generic 0003:04D8:FB31.0003: hiddev0,hidraw0: USB HID v1.11 Device [Hanlincrest Ltd.          FUNcube Dongle V2.0  ] on usb-0000:00:14.0-1/input2
[46918.917284] usb 2-1: 1:1: cannot get freq at ep 0x81
[46918.955162] usb 2-1: 1:1: cannot get freq at ep 0x81
It does show as a valid device in gqrx and I was soon decoding audio with it. The easiest decoding was in the VHF II FM broadcast band. After all the work with the 2 MHz wide spectrum from the rtl-sdr it takes a bit of adjusting to start working with 192 kHz spectrum from the FUNcube dongle but qgrx moves that bit nicely when needed.

To the computer, the dongle is an USB device with two subfunctions: an usbaudio device and a usbhid device. The audio device is used to deliver sampled radio spectrum and the hid device is used to control the dongle. This is why it's relatively easy to use softwarewise: modern operating systems have usbaudio support and usb hid control from a user application isn't too hard either.

One of the things I do want is a lot of interesting audio routing to be able to record both the downlink audio and my own audio. So I fired up pavucontrol and gqrx crashed. Restarting gqrx did not work until I closed pavucontrol. Some searching found gqrx crash with Funcube Pro+ which suggests to turn the device off for PulseAudio. Which may seem strange but PulseAudio is also using the alsa drivers which gqrx tries to use. I guess there is some conflict between gqrx and PulseAudio in dealing with the alsa drivers. After switching the FUNcube Dongle Pro+ in PulseAudio I could open the dongle in gqrx and play with audio settings for other channels in pavucontrol.

The setup with gpredict controlling the receive frequency of gqrx also worked fine, so this is looking good. Now to find out how things work on an FM or linear satellite.

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2019-07-08 I participated in the DL-DX RTTY Contest 2019 4 months ago
RTTY contest on websdr This weekend was the DL-DX RTTY Contest 2019. In the category 'B': single operator, multiband, 6 hours. Not in the category for dipole or groundplane antenna since I used the endfed antenna.

I made 80 contacts, 37 on the 20 meter band and 43 on the 40 meter band. Propagation wasn't great and most of my contacts were search & pounce mode, answering calls from other contest stations. I did call CQ a few times, and one of those was spotted by the reverse beacon network instantly and gave me 3 contacts in short succession.

Operation in the contest was limited due to other things in the weekend so I fitted in the 6 hour category nicely. I did some other things on the radio on Sunday and somewhere in the afternoon I noticed a funny electronics smell and the output power from the amplifier had dropped. I found out the output voltage from the modified HP DPS-700 GB server power supply had dropped to about 10.6 volts. Time to find out whether this problem fixes itself or it's time to find another server power supply that will deliver over 40 ampere current at somewhere around 13 volt.

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2019-06-26 De test gedaan: een draadloze microfoon afgeluisterd 4 months ago
Ontvanger draadloze microfoon

Ik was vandaag weer eens op de lokatie waar ik eerder tot de conclusie kwam Je draadloze microfoon is prima af te luisteren en dit keer heb ik die bewering gecontroleerd.

Niet eens met een scanner maar met een nog makkelijkere aanpak: een laptop met een rtl-sdr dongle er aan en gqrx er op.

De draadloze microfoons en de ontvangers op die lokatie zijn van Sennheiser, wat als voordeel heeft dat ze niet in kanalen denken maar dat de frequentie waar ze op staan gewoon op het display staat. Ik kon dus simpel aflezen van de ontvangers waar ik de microfoons moest 'zoeken'. In een testje kon ik inderdaad de draaggolf van de microfoon prima vinden na inschakelen en met een FM demodulator ook het geluid prima weergeven op de laptop.

Omdat dit een bijeenkomst was waar ook informatie besproken werd die niet vrij de wereld in mag was ik hier even alert op. Maar dankzij een toegevoegde ruimtemicrofoon aan het plafond werden de draadloze microfoons niet gebruikt tijdens de bespreking van gevoelige informatie. Na de besprekingen ben ik even aan de gang gegaan met de laptop en kon toen de ingeschakelde microfoon prima ontvangen.

Op zich is er niets mis met draadloze microfoons, maar er zijn dus situaties te bedenken waarin je denkt dat je stemgeluid alleen binnen een beperkte ruimte versterkt wordt maar wat er net buiten misschien ook opgevangen wordt.

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2018-08-12 Making the HP DPS-700GB power supply less noisy 1 year ago
The HP DPS-700 GB power supply adapted to feed the linear amplifier has no own internal fans so I connected a recycled 50mm PC fan. Which runs at full speed which is a lot of noise. I ordered a 12 volt fan control module on-line so it can run slower and keep the noise down a bit.

I'll probably replace the current fan with an 80mm PC fan and set a low minimum speed. The air has to move as the power supply has no internal fans and is quite good at a thermal shutdown. But as long as things don't get warm it would be nice to reduce the noise as this was very noisy.
Read the rest of Making the HP DPS-700GB power supply less noisy

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2018-08-06 Rich chunky amps from a HP DPS-700 GB server power supply 1 year ago
At a hamfest a scouting group was offering a HP DPS-700 GB power supply for the nice sum of 5 euro. A quick search with google found information about the pinout so I bought it. This is a power supply that can deliver 56 Ampere at 12 Volts, and the 12 Volts can be adjusted upwards somewhat.

As usual with projects like this the power supply lived in the stack of projects for a while, but today I got around to testing it. Finding the pinout again was a bit hard, but I found the pins again at HP DPS-700GB 80mm fan shroud - Thingiverse which includes the simple modification to make the output voltage go up.

As this power supply has no internal fans and will stop fast due to internal overheating if not cooled, I set it up with a recycled computer fan. Power supplies like this will always be active in systems with enough fans to push air through the whole chassis.

The first test gave me 12.1 Volt. After adding a 1.5 kOhm resistor it went to 13.27 Volt. In theory the maximum current may have dropped as a result of this modification, but my best guess is that it can still deliver 50 Ampere.

Update: More about this power supply and the different types seen in the wild: Increasing voltage on DPS-800GB A / ATSN-7001044-Y000 K1000 / HSTNS-PD05 for amateur radio - PA0FRI

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2018-04-24 Building my own balun, part 7: Better measurements of the result 1 year ago
Homemade balun version 2 SWR scan 1-60 MHz
Homemade balun version 2 SWR scan 1-60 MHz 20180424
Homemade balun version 2 SWR scan 10 meter band
Homemade balun version 2 SWR scan 10 meter band 20180424
Homemade balun version 2 SWR scan 20 meter band
Homemade balun version 2 SWR scan 20 meter band 20180424
Time to do measurements of the revised attic antenna. And now with a voltage balun with more windings the balun is working better, showing ok SWR values. A nice optimum in the middle of the 20 meter band (although I originally wanted that optimum near the digital mode part) and a nice optimum in the 10 meter band (also somewhat higher than originally planned). Comparing them to the original measurements show an increase in frequency in both SWR curves.

So I consider this a good result! Time to get it on the air and make contacts again.

Next step, working on an outside dipole with the Fritzel balun.
Read the rest of Building my own balun, part 7: Better measurements of the result

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2018-04-23 Building my own balun, part 6: Redo and some success: a working antenna again 1 year ago
After the previous measurements showed the balun and dipole under the roof weren't acting as a perfect combination. So time to do a few things better: more windings, less leftover wire and a switch to a voltage balun. Yes, other sources indicate a current balun is better, but I decided otherwise. The Fritzel balun turned out to be a voltage balun after I removed it from the dipole antenna.

Balun project version 2 in case So I used the instructions at 1:1 voltage balun by VK6YSF to rebuild it as a voltage balun and I made sure the wires were shorter in the end. Getting the shorter wires in the right places in the case did get me some slightly burned fingers!

Success is currently defined as "I can transmit a carrier on the 20 meter or 10 meter band and the SWR meter of my radio only goes up a few segments" which isn't very scientific, I will need to do the rest of the measurements with the SWR meter to be sure.
Read the rest of Building my own balun, part 6: Redo and some success: a working antenna again

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2018-04-16 Building my own balun, part 5: First tests of the result 1 year ago
Homemade balun SWR scan 1-60 MHz
Homemade balun SWR scan 1-60 MHz 20180415
Homemade balun SWR scan 10 meter band
Homemade balun SWR scan 10 meter band 20180415
Homemade balun SWR scan 20 meter band
Homemade balun SWR scan 20 meter band 20180415
So I removed the old balun and installed the one I made. Removing the old one wasn't easy: the Fritzel balun has a cover over the SO239 connector which makes the heavy duty connector I used very hard to unscrew. So I had to break bits of that cover to get the needed access. And the connector ended with a lot more scratches from my attempts to get access to it.

But now the balun is replaced, and measured. And it looks like some things have changed now causing the antenna to be 'mistuned'.

Update: Just some measurements and thinking: adding the big common mode choke in the mix makes the combination show better SWR curves (still not what I want) but with the frequency with the best SWR still too low. This suggests (to me) two things: I need more windings on the ferrite core and less extra wire length from the core to the connectors. Time for a rebuild.
Read the rest of Building my own balun, part 5: First tests of the result

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2018-04-15 Building my own balun, part 4: Deciding on where to put dipole ends and finishing it 1 year ago
Balun, case and ferrite core Balun in open case I finally decided where to put the holes in the case for the dipole ends of the balun. This took some serious pondering!

I made those holes, put screws through them and wound the ferrite core with enamelled copper wire. To guess the needed length of wire I first wound it with packing rope, made a small knot at the point where it was enough and unwound the rope to measure the length I used and took a bit longer wire.

Using sanding paper I removed the enamel isolation from the ends of the wires and used soldering tin on it.

Other parts of this project:

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2018-04-04 Building my own balun, part 3: First work on the case 1 year ago
Balun project case Balun project case The first work on the balun case was placing the SO239 socket. This included drilling a hole in the case of the right size and at the right position. Figuring out where to put it was mostly influenced by the fact that the ferrite core has to be placed inside the case and I wanted the SO239 socket, the ferrite core and the output terminals not all jammed together. So the SO239 socket was not going to be in the center. For this my new caliper was a useful tool and I measured the inside size and the wanted location of the socket. And I figured out I could drill a 16mm hole and the SO239 socket would fit inside while leaving enough room for the mounting flange.

Holes were drilled and things worked out fine, so the SO239 socket is now mounted. After checking the future location I realized I will have to mount the balun with the SO239 socket facing downwards because the antenna cable is quite heavy. This has to be taken into account with the next steps.

Other parts of this project:

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2018-04-04 Building my own balun, part 2: measuring the 'old' balun 1 year ago
Fritzel balun SWR scan 1-60 MHz 20180325
Fritzel balun SWR scan 1-60 MHz 20180325
Fritzel balun SWR scan 10 meter band 20180325
Fritzel balun SWR scan 10 meter band 20180325
Fritzel balun SWR scan 20 meter band 20180325
Fritzel balun SWR scan 20 meter band 20180325
Since I want to replace a balun that has been up there for ages I want to be able to compare the two. So I used the antenna analyzer to get graphs of the SWR over the whole possible range (1-60 MHz) and on the amateur bands it was built for: the 10 meter band and the 20 meter band.

There was a very interesting difference with the earlier results on the 10 meter band when I first tested the SARK100 antenna analyzer from Linux. The 10 meter band dipole probably moved a bit or something else changed.
Read the rest of Building my own balun, part 2: measuring the 'old' balun

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2018-03-19 Building my own balun, part 1: idea and parts needed 1 year ago
I was considering hanging a dipole antenna outside. This would need a balun and I realized that I have a good outdoor-capable balun hanging in the attic. It's a Fritzel 1005 1:1 current balun which is good up to 300 watts power.

I am not going to use 300 watts under the roof close to other equipment and the balun there does not need to be rain proof. So the idea was born to build a smaller balun for use under the roof and have the Fritzel balun available for outdoor use.

And last Saturday was a hamfest (radio onderdelenmarkt Rosmalen) so I had an idea of things I wanted for this project.

Parts needed for a current balun:
  • A ferrite core with the right specifications
  • Wire with enamel coating
  • An SO239 socket
  • Terminals for connecting the dipole wires
  • A case
The various collections of electronics parts only missed the SO239 socket and a case. Those were found at the hamfest for a nice price.

The choice of design is a current balun or a voltage balun. I had to do some searching to find a good comparison between the two, and DX engineering has one at Baluns: Choosing the Correct Balun - DX Engineering which has:
Current baluns, rather than voltage baluns, should be used whenever possible. Current baluns provide better balance and often have lower loss. Current baluns, especially 1:1 ratio baluns, tolerate load impedance and balance variations much better than voltage baluns.
Some searches found good explanations of building your own baluns, I found a very clear explanation at VK6YSF project page.

So I'm building a current balun, and when it's finished enough to test it I will measure how it is doing. I have the tools like the SARK100 antenna analyzer that I can control from Linux and a dummy load so I can check everything.
Read the rest of Building my own balun, part 1: idea and parts needed

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2017-09-08 I built a common mode choke 2 years ago
After the problems with the laptop controlling the radio when I participated in the SCC RTTY contest 2017 I decided to build a common mode choke. This is a filter that should keep the radio frequency signals at the side of the antenna.

Based on the simple design with a piece of PVC pipe with 8 windings of Aircell-7 coax I still had lying around. The PVC pipe was donated by a fellow radio amateur who had it in his junkbox.

I drew a pencil line on the pipe, decided where to drill holes for the coax cable (using a 16 millimeter drill) and where to drill holes for tiewraps to hold the coax. After drilling the holes it was a matter of winding the coax correctly, mounting the cable with tiewraps and soldering the connectors to the cable.

In the first testing the filter worked fine, completely stopping the interference to the keyboard of my "shack computer" and even reducing incoming noise on the 10 meter band.
Common mode choke: materials - KvdHout on FlickrCommon mode choke: materials
Common mode choke: finding where to drill holes - KvdHout on FlickrCommon mode choke: finding where to drill holes
Common mode choke: holes drilled - KvdHout on FlickrCommon mode choke: holes drilled
Common mode choke: cable mounted - KvdHout on FlickrCommon mode choke: cable mounted
Common mode choke: connectors done - KvdHout on FlickrCommon mode choke: connectors done

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