I passed my novice radio amateur exam in March 2013 and I registered the
PD4KH (pappa delta four kilo hotel!).
I passed my full radio amateur exam in March 2016 and I registered the callsign
PE4KH (pappa echo four kilo hotel!).
PE4KH on qrz.com
PE4KH on hamqth.com
I am usually located around maidenhead locator: JO22NC
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.proThis 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.
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.
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.
My sark100 antenna analyzer
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
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.
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:
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 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 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.
- 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
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.
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.
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.
In my project to receive amateur satellites with the rtl-sdr I noticed the sdr itself has a considerable 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: 36428.54Second 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 ppmAnd 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.