News items for tag hamradio - Koos van den Hout

2017-06-18 I participated in the Ukranian DX Classic RTTY Contest 2017 5 days ago
I participated in the Ukranian DX Classic RTTY Contest 2017 this weekend. I prepared the antenna and the contestmacros Friday evening, but I knew most of Saturday afternoon and Sunday morning would be unavailable.

Local noise was bad, it seems interference from solar panels is on the rise and it was a quite sunny day.

On the other hand, there was a 10 meter band opening Sunday afternoon, giving me some new multipliers with 8 contacts on that band. But no serious DX in the whole contest, I just saw Eastern Europe and Asiatic Russia active, unlike when I participated in the Ukranian DX Classic RTTY contest 2016.

The end result is that I made 70 contacts in somewhat less than 6 hours of operating time. So I participated in the SINGLE-OP ALL 6-HOUR RTTY category.

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2017-06-18 Sunny interference 5 days ago

A good sunny day and the effect it has on the HF spectrum: extra interference from solar panels. I'm not sure whether to complain about all solar panels not regularly identifying with their callsign or complain about interference or just give up and find another location for amateur radio.

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2017-06-14 Controlling the SARK100 antenna analyzer from Linux 1 week ago
The SARK100 antenna analyzer I bought also has the option to be controlled over an USB interface (other versions even have bluetooth support). Over USB it is possible to automate the measurements and have the results returned to the controlling computer.

For Linux software is available: SARK100 Antenna Analyzer Linux Software also via github with updates coddingtonbear/sark-100-antenna-analyzer.

I cloned the git repository and guessed that the command to build a 32-bit version would be:
koos@thompson:~/radiowork/sark-100-antenna-analyzer$ mkdir build
koos@thompson:~/radiowork/sark-100-antenna-analyzer$ cd build
koos@thompson:~/radiowork/sark-100-antenna-analyzer/build$ qmake -spec linux-g++ -o Makefile ../analyzer/analyzer.pro
This indeed compiled into a working 32-bit binary. Needed because the 'main radio desktop' can't run a 64-bit linux. The laptop does not have this problem.

Attic dipole on 10 m analyzed by the Sark100 analyzer and linux software
The attic dipole on 10m analyzed with the Sark100 analyzer and linux software
Attic dipole on 20 m analyzed by the Sark100 analyzer and linux software
The attic dipole on 20m analyzed with the Sark100 analyzer and linux software
And after compiling the software comes using the software. It works nicely and does what it says on the packaging.

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2017-06-06 Testing a different antenna setup and having fun on the 10 meter band 2 weeks ago
Almost three years ago I started making PSK31 contacts on the 10 meter band which was my first experience with HF and propagation through the ionosphere as a novice amateur with callsign PD4KH. The 10 meter band is the amateur band from 28.0 MHz to 29.7 MHz.

But the propagation through the ionosphere depends on the solar cycle. Currently the cycle is going towards a solar minimum meaning the number of sunspots is very low. Due to the low number of sunspots the propagation of radio signals through the ionosphere back to earth is also very low. After I upgraded to a full license opportunities to use the 10 meter bands were very rare. Up until yesterday I had 5 contacts in the log for PE4KH on the 10 meter band.

And yesterday that changed. I was testing with a borrowed fiberglass pole since I want to use that to help me tune the linked dipole kit I bought. I set up the fiberglass pole in the back of our garden using the fence for support and raised it to the full 10 meters with the endfed spiralled around it. At the end I had some wire left to the transformer so I just hung the transformer in the back garden. It took a lot of cable to get from my radio to the antenna far away, but I really wanted to do that experiment, especially to get an idea of the influence on the local interference. On the 20 meter band the interference was about the same, on 40 meters it was a bit less but on 10 meters it was almost gone.

And at the same time there was interesting propagation on the 10 meter band. I made several contacts with stations in Poland, Austria, Italy, Northern Ireland and Scotland. Most of those contacts would not have been possible with the noise levels I am used to.

An interesting experiment in radio. My first thought was that this antenna setup might be interesting for contesting, but I realised that I really need to keep an eye on the power levels since there is a small footpath right behind our garden for our neighbours. I can't ask them not to use that footpath for an entire contest weekend.

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2017-05-22 I bought a SARK100 antenna analyzer 1 month ago
My sark100 antenna analyzer
My sark100 antenna analyzer
In september 2016 I ordered a balun and a linked dipole kit from sotabeams with the idea to make a lightweight dipole antenna for outdoor use. But there is one very important ingredient to making a dipole: you need an antenna analyzer to get the dimensions right to have optimal reception and transmission into a resonant antenna.

I could borrow the antenna analyzer from the club just like I did for measuring my 2m/70cm portable coax antenna but after reading about the (cheap) SARK100 antenna analyzer I decided to buy one myself. One good review I found is It finally arrived! My SARK100 from China. This analyzer seems to be a serious case of an 'open source' design being picked up by the Chinese electronics manufacturers and sold in high numbers. I bought one for a reasonable price at an aliexpress seller that had good reviews and orders before.

It arrived today and the first tests look really good. First I measured my dummy load (to get an idea of how it was doing as an analyzer) and after that the 10m/20m/40m endfed antenna that was hanging outside anyway for the EU PSK DX Contest 2017 that I participated in. This antenna isn't perfect (as visible in the picture) but it does the job.

So now I have to find the time to design a linked dipole as I want it, build it and measure / adjust it until it does what I want.

It's a good thing I can easily calculate linked dipoles at Various tools for SOTA purposes. My plan is to build a 15-20-40 meter band dipole. The selection of bands is because outdoors I will use less digital modes and 40 meters is the longest size for a dipole that is usable to set up. The angle of the dipole and therefore the height of the centerpoint also has an influence on the antenna. But I don't know how high the tree will be, so I will have to make a guess.

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2017-05-21 I participated in the EU PSK DX Contest 2017 1 month ago
I noted the EU PSK DX Contest in the contestcalendar and decided to participate. Conditions did not cooperate very well and I found some issues with my setup during the contest. But in the end I made 57 contacts. Not very good given my scores earlier this year but I think the big issues with local HF noise started after the previous contest.
Total number of QSO in your log is 57, Including 0 QSO with errors, Valid QSO - 57
Band  QSOs Dupes Points Mults
160      0     0      0     0
80       0     0      0     0
40       0     0      0     0
20      57     0    117    64
15       0     0      0     0
10       0     0      0     0
======================================
Total   57     0    117    64
Claimed score is 7488 points

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2017-05-14 Upgrading the home network to shielded/foiled cable (s/ftp) 1 month ago
I was looking at on-line offers of shielded/foiled network cable and found out it's not that expensive anymore. And with the 'keystone' connectors it looks like it's not that complicated to make neat and very well shielded connections.

But it's always a good plan to check the local electronics hobby shop. We still have one in the center of Utrecht: radio centrum where they had 1 meter and 2 meter patchcables for a very nice price (competitive with on-line shops) right up for grabs. So the first set of short cables that are always in use for gigabit are now s/ftp category 6 cables. I hope this improves radio reception.

I still think I will order longer cable and keystone connectors and holders for the longer cables.

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2017-05-10 Digging for the source(s) of HF interference with a complete powerdown 1 month ago
Today I had planned to dig deep into the sources of the HF interference by switching off the electricity in the whole house and seeing what difference that would make and if it did, search for sources.

I used the 10-20-40 meter band endfed outside, and the 10-20 meter dipole inside. The conclusions are mixed:
  • The 40 meter band (that I can only use on the endfed) is not influenced at all by switching off the power.
  • The 20 meter band on the dipole gets somewhat less noise when the power is down.
  • The 20 meter band on the endfed gets the same amount of noise when the power is down.
  • The 10 meter band on the dipole gets no noise at all when the power is down. Change from S8 noise to S0 noise.
  • The 10 meter band on the endfed gets 2-3 points less noise when the power is down.
So for the 10 meter band and less for the 20 meter band it was good to search in the house for sources of the noise. Found:
  • The lights in the attic
  • The UPS for the server
  • The netgear switch downstairs when ports become active. The switch upstairs probably too, but it's behind the UPS, so interference from the UPS showed up first
  • The wireless accesspoint downstairs
So the problem sources that I can't switch off easily are all part of the home network. My current theory is that 10 meter seems to be affected by gigabit network. My experience is that transmitting on 10 meter indoors causes a network outage.

The home network is all Cat-5E at the moment, unshielded twisted pair. It seems an upgrade to s/ftp is in order (with foil and braided wire, the same I do for antenna cable).

The thing is that with the current solar cycle 10 meter use is very rare. I haven't made a contact yet in that band in 2017.

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2017-05-08 Going full duplex with amateur satellites, part 11 : Tried an XW-2A pass, heard vague signals, no contacts 1 month ago
This evening the only amateur satellite pass at a reasonable time was by the XW-2A satellite, part of CAMSAT XW-2 Satellites - amsat UK and I only heard weak signals which sounded like other radio amateurs tuning their transmitters/receivers but I never heard something like a voice. Or my own signal when I tried transmitting.

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2017-05-07 Going full duplex with amateur satellites, part 10 : Still no contacts, investigating AO-85 (Fox-1a) 1 month ago
Passes of amateur satellites aren't always at times that are compatible with other things happening. But the discussion about AO-85 on the amsat-bb mailing list also had some details about the satellite and I also found AO-85 Twist Trick and Other Hints - Spacecomms which explains:
Apparently the epoxy caused a change in impedance which essentially “detuned” the antenna. It makes the bird appear deaf. A workaround is to twist the Arrow antenna 90 degrees when you transmit. That is, rotate the antenna until the receive signal is “peaked” and then rotate it 90 degrees when you transmit and back again to receive.

The downside to this is if you’re working full duplex when you rotate the antenna 90 degrees to transmit you will often lose the downlink signal and not be able to hear yourself. In my experience I only have to do the twist trick in the beginning and end of the pass when the bird is farthest away.

Another fix is to just use more power, but if you only have an HT that’s usually not an option.
This, combined with the frequencies up and down being slightly different from the planned frequencies explains the weak signals I hear upon receiving and the difficulty I had getting into the satellite.

This evening had a pass of AO-85 which did not leave me time to drag out the whole setup, but I was able to bring the arrow antenna and a handheld radio to check reception to see if the frequency was correct, including doppler correction. It was correct, but reception is indeed quite sensitive to the orientation of the arrow antenna.

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2017-05-01 Going full duplex with amateur satellites, part 9 : Filtering the reception, in theory 1 month ago
I decided to share my woes of the receive side going deaf (receiving nothing) when I transmit with the amsat-bb mailing list, together with a description of the whole setup. The suggestion came from Eduardo PY2RN to not use a preamp and have filtering so the transmitted signal cannot get into the receiving side.

I pondered this for a while and realised I already have a filter: the diplexer on the arrow antenna. So to receive on 2 meter and transmit on 70cm I connect the transmitting radio to the 70cm antenna and connect the receiving radio (the rtl-sdr) to the 2 meter antenna via the diplexer, and put a 50 ohms terminating resistor on the 70cm connector of the diplexer to make sure it still shows the right impedance.

In a simple test this works, transmitting now has a lot less influence on the rtl-sdr (it's not completely gone yet). I haven't had a good satellite pass yet to try this out.

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2017-04-29 Using kalibrate-rtl to calibrate the rtl-sdr frequency 1 month ago
In my project to receive amateur satellites with the rtl-sdr I noticed the sdr itself has quite a frequency error as noted in Going full duplex with amateur satellites, part 5 : first test of the amplifier with RTL-SDR.

Using the PI2NOS output frequency I ended up at an error of 54 ppm so I entered that in gqrx. But to be really sure there is a program named kalibrate-rtl available via GitHub - steve-m/kalibrate-rtl: fork of http://thre.at/kalibrate/ for use with rtl-sdr devices.

I had some trouble finding the right way to use this program so I am sharing my steps here. First try to guess the error by using a known frequency such as a local repeater (especially when they mention using GPS to maintain frequency) or a broadcast FM station.

First step with kalibrate-sdr is to scan for GSM channels which are strong enough. I noticed in later runs that I really need to add the first guessed frequency error, otherwise it will not find the GSM channels at all.
koos@kernighan:~/radiowork/kalibrate-rtl/src$ ./kal -s GSM900 -e 54
Found 1 device(s):
  0:  Generic RTL2832U OEM

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Exact sample rate is: 270833.002142 Hz
[R82XX] PLL not locked!
kal: Scanning for GSM-900 base stations.
GSM-900:
        chan: 8 (936.6MHz + 724Hz)      power: 67277.85
        chan: 17 (938.4MHz + 606Hz)     power: 36428.54

Second step with kalibrate-sdr is to select a GSM channel to use for the calibration run. I selected channel 8 which looks quite active.
koos@kernighan:~/radiowork/kalibrate-rtl/src$ ./kal -e 54 -c 8
Found 1 device(s):
  0:  Generic RTL2832U OEM

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Exact sample rate is: 270833.002142 Hz
[R82XX] PLL not locked!
kal: Calculating clock frequency offset.
Using GSM-900 channel 8 (936.6MHz)
average         [min, max]      (range, stddev)
+ 169Hz         [85, 251]       (166, 49.119198)
overruns: 0
not found: 0
average absolute error: 53.820 ppm
And only in that step you get the output with the calculated frequency error.

Update: Doing this calibration is also a good idea for the stick running the ads-b receiver. That came out to -30 ppm and using that factor makes dump1090 receive signals from greater distances.

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2017-04-29 Going full duplex with amateur satellites, part 8 : No real contact yet 1 month ago
This evening had a Fox-1A (AO-85) pass at a reasonable time so I decided to drag the entire setup outside and try my luck at a qso. Reception of Fox-1A was bad (maybe I'm somewhat off-frequency) and the major dissapointment was that the receiving side on 2 meter via sdr got deaf when I was transmitting on 70 centimeter. That's not supposed to happen, the whole reason for the full-duplex setup was to be able to hear myself on the downlink.

Anyway, the recording of downlink audio went fine this time so there is a full recording of what I heard. It was a Northwest-Southeast pass which means it took a while before I heard anything because northwest is over the houses. Callsigns heard in this pass: DO3EXE, IZ5ILX, 9A2EY, IZ3KLF, Something with F2D I completely can't decode and "Mr Olla".

My best guess would be a retry on SO-50, FO-29 or AO-73.
Listen to audio attachment:
MP3 media: 20170429 1858Z FOX-1a pass recorded by PE4KH in JO22NC (rightclick, select save-as to download)

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2017-04-24 Somewhat less HF interference by moving the antenna away 1 month ago
I was testing with noise on all radio bands with the LW-10 longwire antenna with tuner. I recently made the rope that hangs it out from the window a bit longer and I noticed the noise on the 10 meter amateur radio band had dropped a lot compared to the noise I experienced before and the noise on the antenna under our roof. In S-points: under the roof S8, with the 10/20/40m endfed S8, and with the longwire antenna S0.

On bands with lower frequencies (higher wavelengths) noiselevels were high, up to S9+ on 80m with a rattling noise in it. But this sudden change on the 10 meter band made me think there could be a pattern so I measured how much more distance I could move the antenna away from the house and maybe get lower noise levels on the 20m band too. After adding 1.60 meter of rope and rehanging the antenna the noise level on the 20 meter band also dropped from S8 to S7. Not the biggest improvement but it's something.

I'm now making some PSK qso's on the 20 meter band. At the S8 noise level this was getting impossible.

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2017-04-23 Going full duplex with amateur satellites, part 7 : Recording downlink audio 2 months ago
This evening I thought there would be a nice Fox-1A (AO-85) pass but gpredict on another computer showed totally different predictions. Pondering that difference made me suddenly remember AO-85 is still not part of the 'standard' set of Kepler data because it's close to some militairy satellite. The data is available through other sources, I use TLE | Amateur radio PE0SAT and updated from that location. The 'nice' AO-85 pass near 22:30 localtime shifted to 'way too late', so I looked for other satellites to at least try recording downlink audio. I saw passes of HO-68 and UO-11. So I created the whole setup with audacity recording audio. Using pavucontrol I adjusted the recording flow of audacity to record 'Monitor of Built-in Audio Analog Stereo' and indeed audacity was recording the same as I heard on my headphones.

But no signal from the satellites was received. Checking the Amsat Oscar status page shows both haven't been heard by others either. So I recorded noise, but I recorded the right noise.

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2017-04-23 New band in amateur radio: 60 meters (5 MHz) 2 months ago
Today I was scanning the bands to build an overview of noise / interference levels on each band and I came across the 60 meter band (5 MHz) which I can get tuned on my LW-10 longwire antenna. No idea how much power is eaten by the tuner and how much gets out but it works. I noticed some RTTY signals and those were within the part of the band I can access with my license.

So I answered the CQ from DK7UY and we had a good contact.

The 60 meter band is a recent addition for Dutch and other amateurs, only allowed since 3 december 2015. Around that date the WRC-15 conference happened where world-wide agreements were made about secondary amateur access to this band. And on 1 april 2017 the access for Dutch amateurs was limited to the agreed allocation.

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2017-04-22 Going full duplex with amateur satellites, part 6 : First succes in reception 2 months ago
Today I had time for a reception test and when I started collecting the amateur satellite reception gear I saw two upcoming passes, one of the AO-73 Funcube and one of the AO-85 Fox-1a satellite.

The AO-73 Funcube is an 'inverting transponder' which converts an LSB uplink to an USB downlink with space for multiple contacts at the same time. By default gpredict selects the center frequency where I heard PA3HDG calling CQ but hearing no answer. Sorry, I did not have the rest of the setup to transmit that answer.

The AO-85 Fox-1a is like an FM repeater in space so it should be easier to receive it. But I heard nothing, which was most likely due to the satellite being in a part of the sky where the hedge is in the way. due to the fact my data about that satellite wasn't updated: it's not in the default sets. Updating from a trusted source of extra kepler data TLE | Amateur radio PE0SAT showed a shift in pass times of more than 60 minutes.

Anyway, first success in reception. Next steps: recording the received audio with audacity and adding the transmitter to the mix to be able to make actual contacts. At least the concept I imagined with the rtl-sdr stick as receiver so I can work full-duplex works.

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2017-04-14 Going full duplex with amateur satellites, part 5 : first test of the amplifier with RTL-SDR 2 months ago
For a first test I looked for the first reasonable pass of an amateur satellite and tried to recieve the morse beacon of HO-68. I have received signals from HO-68 before, but this pass I heard nothing.

I tried a stable regular local source on the 70cm band : the PI2NOS repeater and noticed after a while the frequency display in Gqrx was showing 430.100 MHz where the (GPS stablized) frequency is 430.125 MHz, so the RTL-SDR I use is somewhat off frequency. Maybe in a next test things work better.

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2017-04-14 Going full duplex with amateur satellites, part 4 : amplifier built into the case 2 months ago
Today I had some time to work on the metal case for the amplifier I bought for receiving amateur satellites. I've never been good at metalwork but I think I did ok. First I made sure the place I wanted to put the holes was chosen correctly, taking the size of connectors into account. Especially with metalwork it's "measure twice, cut once". Next I drilled holes with a drill for metalwork (HSS) and used a file for metalwork to make the holes bigger. I visited the local electronics shop to get a small switch for switching the battery power on and off and added a hole for the switch. In the end the amplifier and the cables are mounted inside the case and there is a bnc connector for the Arrow antenna on one side and an SMA connector for the cable to the RTL-SDR stick on the other side.

Battery added for amplifier in metal case - KvdHout on FlickrBattery added for amplifier in metal case

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2017-04-12 Trying the mini-whip as reception antenna 2 months ago
Recently I talked to a fellow radio amateur about my HF reception woes at home and he suggested trying the mini-whip antenna I built a few years ago as reception antenna, using an automatic switch to switch between the transmission and reception antenna.

For the first test I used the mini-whip antenna with the HF downconvertor and an RTL-SDR stick that I bought to receive amateur satellites to check the signal on the computer. The further I move away from the house the better signal I get (less noise, more signals sounding like the amateur radio signals I want). I do notice that when I turn the gain on the RTL-SDR up (or set it to automatic gain) that there is a repeating 'ticking' signal which sounds just like the ticking interference from my own PLC tests.

This could mean that a nearby neighbour has a PLC network without the notches for amateur radio. Or this is just an artefact of the high gain.

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