News items for tag electronics - Koos van den Hout

2020-04-13 Beeping -- --- .-. ... . loud enough (2) 1 month ago
Today I had time to work on the transistor switching to make the morse oscillator work. As I noticed before the Kent Morse practise oscillator kit is powered directly via the key which draws more current than the nanokeyer I built can handle.

So I had to calculate a transistor switch. That's something I learned a long time ago when I did electronics trade school from 1985 to 1989. In Dutch: MTS electronica. That knowledge had to be dug up again when I did the advanced radio amateur course but since I didn't have to use that knowledge it all sunk away.

But, google to the rescue and I found lots of examples, but the easiest one was at Transistor as a Switch - ElectronicsTutorials which explained exactly what I wanted. The next item was 'which transistor'. The default NPN transistor is the BC547B, but the theoretical current through the oscillator is a bit more than this transistor can handle. But a fellow amateur had a few BC337 transistors spare in his junkbox, so I could continue with this project.

Today I did the drawing and the calculations. I looked up the specifications for the BC337 in full saturation, at which time the Vbe is 1.2 Volt, Vce is 0.7 volt and Ibase is 1 milliAmpere. So I ended up with a resistor of 6800 Ohm at the input (which is (9 Volt - 1.2 Volt)/1 millAmpere rounded) and after building it on a breadboard it went beep with an input current of somewhat over 1.0 milliAmpere.

Update: Second test was with the nanokeyer, which first gave no sound, but that was due to me turning the volume down on the practise oscillator. Turning it back up fixed the problem, and I now have loud morse!

In the end this is giving me a good feeling. I had a kind of problem I haven't had to solve in ages so I had to relearn how to solve this, I found the solution method and was able to apply it in theory, practice followed the theory and it all worked as designed.

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2020-04-02 Beeping -- --- .-. ... . loud enough 2 months ago
Kent morse practise oscillator built
The Kent morse practise oscillator built
To practise my morse at the radioclub I looked for a simple morse practise oscillator and found Morse practise oscillator kit - Kent and ordered it at the beginning of Februari. It took a while for it to arrive, but it arrived and I built it in one evening.

It's a quite simple kit. Which means the power for the whole circuit runs via the morse key, in theory about 120 mA. And that is more than the octocoupler on the CW output of the nanokeyer I built is willing to deliver (50 mA). So I can't use the practise oscillator straight away, there will need to be a small amplifier in between.

Some searching suggests I can use a transistor as 'power amplifier'. Time to look at what I may have (which is not a lot) or find a transistor somewhere.

Solution: order a bunch of transistors in a collection so I have some in the junkbox.

Oh and: The dashes and dots in the title are the word 'MORSE' in morse.

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2020-03-09 Newer power supply not yet delivering what I want 2 months ago
I did some more testing with the HP power supply I bought last November. In previous tests the output voltage seemed to be limited at 13 volts and it seems limited to 13.10 volt at the moment. The RM Italy HLA300V plus amplifier I have will only output about 55 watts maximum in digital modes so that's less than I expect. A higher input voltage may fix this, but I'm not sure how to get the power supply to deliver this and keep running. The previous power supply gave up in a busy weekend but before that the HF linear amplifier delivered more power. I have seen it go over a 100 watt on digital modes. The difference in output from the linear amplifier with 13.10 or 13.27 volt power is quite large, which surprises me.

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2019-11-23 PC control of the TS-480 radio working again, including for remoterig 6 months ago
I dug into the "why isn't remote CAT control not working" on the Kenwood TS-480SAT with the remoterig setup and as the debugging session progressed I found out it wasn't even working locally. The Kenwood TS-480 radios have a male db9 connector just like the PC had, and the non-intuitive part is that it needs a straight-through cable with data lines and hardware flow control.

I had a bunch of serial cables and adapters cobbled together to get from DB9 female to DB9 female with wires 2 and 3 coming out uncrossed, but it did not have hardware flow control and that had worked one evening before but now it decided to go on strike.

Thanks to the visit to the "Dag van de radio amateur" (DvdRA) ham convention and the extra parts ordered on-line from Conrad I had enough parts to make my own serial cable with the right wiring, including covers for the connectors with the cable coming out on the side.

So my skills in building right serial cables using a soldering iron, flexible wire and an amount of patience were recalled. I am very sure I haven't done that yet this century. Old CAT-5E cables are a good source of flexible cable with 8 wires.

When I had a finished cable with hardware flow control I first did a local test before I started putting the covers on the connectors and when that did work fine I put the covers on, redid the test and switched to testing over the remoterig connection. That also worked.

Update: And for the laptop which doesn't have serial ports I activated the COM port to USB translation on the control side. It took a bit of searching before I found that /dev/ttyACM0 was the active port, so now I can run CQRLOG on the laptop with full control of the radio.

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2019-11-16 Getting distracted by weird noises and listening to data from car tires 6 months 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 6 months 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 7 months 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 7 months 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 8 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.

Earlier steps: the nanoKeyer tested and working after assembling the electronics, starting with the nanoKeyer kit.

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2019-09-06 The nanoKeyer morse keyer is working 9 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.

Earlier steps: starting with the nanoKeyer kit.

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2019-09-04 New electronics project: a morse keyer 9 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+ 10 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 11 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 11 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.
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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 2 years 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 2 years 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 2 years 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 2 years 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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