A roaring machine, morse code and Irish folk music – celebrate the UN Day of October 24 at the World Heritage Site Grimeton!
Man’s quest for contacts and faster relationships between each other is tireless. A proof of this are the many attempts made to put a telegraph cable on the bottom of the Atlantic before the seemingly impossible project was finally landed – the connection between Europe and America was established, from Ireland to Newfoundland, and opened for telegram traffic in August 1866 .
We celebrate this great event in international relations by sending out a peace message to the world with the long-wave transmitter SAQ and then a concert in the Irish folk spirit with the Varberg band Green Hill.
Evening program
18.00 The world heritage opens
18.30 (16.30 UTC) all visitors are greeted welcome and the long wave transmitter SAQ is started
19.00 (17.00 UTC) a peace message is sent out*
19.15 (ca) concert with Green Hill
Free entrance. Arrive in time as there are limited amount of seats.
Welcome!
The transmission is on 17,2 kHz CW.
You can also watch a live video stream of the transmission on www.alexander.n.se.
No QSL-cards will be given this time and no List of Reports will be constructed but we accept shorter Listeners Report to e-mail info@alexander.n.se.
*The world heritage site Grimeton is a living cultural heritage. All transmissions with the long-wave transmitter SAQ are therefore preliminary and may be cancelled with short notice.
A scheduled transmission from Grimeton Radio / SAQ on Christmas Eve, December 24, 2018 was announced via email: In the morning of Christmas Eve, December 24, we will try to start the old Alexanderson 200 kW transmitter, from 1924 and send out a Christmas message on VLF 17.2 kHz CW. The transmitter will be tuned … Continue reading "Transmission from Grimeton Radio SAQ on Christmas Eve"
Autumn and winter are great for experimenting on the medium wave band. We’ve tried a 150m baloon-lifted antenna.
Our objectives were:
To see how a quarter-wave vertical works at 472kHz
Testing the hydrogen generator
Determining how much weight can be lifted by a 1m diameter baloon, and how it will behave in the wind.
The results are encouraging. This is an analysis of the experiment:
During the experiment we had very strong wind with gusts up to 15m/s. This, combined with rain, damaged the baloon. In these circumstances a kite would have probably been better. Unfortunately we couldn’t do the experiment when the weather was better. During high winds a string support is needed for the base antenna line. At first we’ve tried a fibreglass/epoxy fishing rod, but the forces were too strong and we had to change it for a wooden pole.
2. It’s best to use a copper-covered welding wire. It’s strong enough and very light. Unfortunately aluminium wire is not strong enough. It’s also best not to use wires covered in isolation, because of their additional weight.
3. If the antenna is to be used during the night, there has to be some means to show the baloon position. We think that it is sufficient to use a simple pulsating LED light powered by a watch battery.
4. The antenna was tuned to resonance with an antenna analyzer by varying the antenna length. This way we were able to quickly determine the correct length of the wire. The SWR varies with the antenna position relative to earth, the range is about 1.3 – 2.3.
5. For ground we used an earthing rod in a 13m deep well. The resistance of this ground is 37Ω at 70Hz, at 472kHz it is probably much higher. The antenna impedance was about 200Ω, so we needed to use a 1:4 transformer to match the antenna. The theoretical impedance of a quarter-wave vertical is around 35Ω, so the rest (200Ω-35Ω=125Ω) is due to loss. This calculates to antenna efficiency around 15%, so we need around 15W to get to the 1W EIRP legal limit.
6. The signal was received by many european stations. Unfortunately the baloon was destroyed by very strong wind and rain before the transatlantic propagation time.
7. The optimal way of generating hydrogen in an amateur setting is the reaction betweem aluminium and NaOH (sodium hydroxide) solution One should not use aluminium dust or fine filings, because the reaction is too quick and overheats. Aluminium soft-drink cans are covered with paint, and the reaction goes too slowly in this case. Larger aluminium shavings are optimal. NaOH can be purchased as pellets used for unclogging pipes. The generator consists of three parts: a hydrogen generator (bottle with the NaOH solution and aluminium), a scrubber (bottle with water that the gas passes through) and preferably a dessicator (third bottle with solid dessicant). You should wear protective gear at all times, and take measures not to harm yourself. A concentrated NaOH solution will cause permanent damage to eyes and the rest of the body. If in doubt, consult a chemist (both of the founders of klubnl.pl have a masters degree in chemistry).
Christmas transmission from SAQ on 17.2kHz, 24 december 2018 8:00 UTC
Received at SQ5BPF QTH Warsaw/Poland KO02md.
E-field active antenna, vlfrx-tools and Spectrum Lab receiver
The message was:
CQ CQ CQ DE SAQ SAQ SAQ = THIS IS GRIMETON RADIO/SAQ IN A TRANSMISSION USING THE ALEXANDERSON 200KW ALTERNATOR ON VLF 17.2KHZ. = WE WISH YOU ALL A MERRY CHRISTMAS AND A HAPPY NEW YEAR = SIGNED THE WORLD HERRITAGE AT GRIMETON AND THE ALEXANDER VETERANRADIOS VAENNER ASSOCIATION = FOR QSL INFO PLEASE READ OUR WEBSITE WWW.ALEXANDER.N.SE WWW.ALEXANDER.N.SE = DE SAQ SAQ SAQ SK
Stefan DK7FC did a succesful transmit experiment utilising a ground diole on VLF. This resulted in a really strong signal on our Warsaw grabber (over 900km distance):
The spectrum after amplitude normalizastion:
The antenna had about 900m and the current was about 1A. A full descrption is avaliable in the rsgb-lf-group list archives:
Sadly the NDB BIA on 474kHz in service at Rzeszów Airport has been turned off.
For many years the carrier at 474kHz and the sidebands at 473kHz and 475kHz were used by polish radioamateurs to check their 630m equipment. Foreign radioamateurs used this NDB to judge the propagation to Poland.
This will change the way we work in the CW segment in the 630m band in Europe. Up to now we had to use 472-472.7kHz or around 473.5kHz, and a narrow filter was necessary. After BIA is switched off we can use the whole 472-475kHz segment, also with wider filters.
The RSGB LF Reflector is the most important group for low-frequency enthusiasts. For many years list members have been witnesses to milestones in the 136kHz, 73kHz, 500kHz, 472kHz, VLF and lower bands. Many posts have great historical significance.
In the beginning this archive spanned from 2014 up to now. Recently we imported archives kindly donated by Dave G3YXM and Markus DF6NM. Thanks to them the archive now spans from February 1999. 20 years of radioamateur longwave (and medium-wave) radio history!
Encouraged by our last experiments with ground dipoles we decided to do a transmit experiment with this antenna on VLF 8.270kHz, 36km (36000m) wavelength. Thanks to Fab LAB Trójmiasto we had a great location on the see on a cliff near the Baltic Sea in Gdynia. Our goals for this experiment were:
Try transmitting from a ground dipole on VLF
Assess the field strength near the sea
See if it is possible to reach greater distances with relatively simple equipment and low power.
Test a broadband transformer for VLF-LF-MF
1. Location
We had a great location on a cliff in the Kolibowski Park near the Gdańsk Bay, and hoped that the ground water level would be low (increasing the ground loop area). We could also use two water bodies for grounding: a nearby lake an the Baltic Sea.
3.Antenna
The antenna length was about 500m. The antenna was grounded a small local lake (using a 1m long aluminum profile) and the Baltic Sea (10m of wire sunk in the Gdańsk Bay). For the antenna wire we used a copper-coated steel welding wire of about 1.2mm circumference (160m) and 0.8mm (the rest of the length). It was not the best material available, but we used it because of low cost. Where possible the wire was strung high in woods and bushes.
A beautiful sight from one of the antenna ends
The other end of the antenna
The antenna parameters were:
Antenna voltage at the feed point: 300V
Antenna impedance at 8.27kHz: about 1200Ω
Resistance measured ad DC: about 500Ω
Calculated DC resistance of the antenna wire: around 140Ω
Transmitter power: around 75W
The radiated power is probably well below 1 uW (0,000001W)
4.Equipment:
– GPS synchronized generator
– A generator based on an old terminal; with an x86 processor, which had a uBlox Neo-7m GPS installed inside. The GPS is connected to the terminal serial port for control, and to use the GPS output for a coarse time reference (this is not very precise because the 1PPS signal is not connected). A 20kHz signal from the gps is connected to the sound card in the terminal and is used as a reference for Paul Nicholson’s excellent ebsynth Linux DDS and modulator
This enabled us not only to generate a carrier, but also to transmit ebnaut
old Polkat Forte 201 public address amplifier
This amplifier has been modified a bit. More output transformer taps were made available on the back connector. Forced cooling with two computer fans was added to enable continuous work at high power.
-The signal was received by Paul Nicholson at a distance of 1342km. As far as we know this is the first international reception of an amateur generated VLF signal from Poland. We transmitted “SP” (which is the prefix for polish stations) using the EbNaut mode on 8270.00073Hz.
From 20190302 11:30 UTC to 20190303 04:00 UTC we transmitted a carrier on 8270.005Hz. This was visible on Paul Nicholson’s grabber:
-We measured the magnetic component of the field using a 90cm diameter loop antenna. The signal was visible at about 6km distance even with a fast FFT. At first we used 131072 FFT size with 48kHz sample rate: 370mHz per FFT bin, 2.7s FFT window time, later we added 32x decimation, which gave 11mHz per FFT bin, 1.5min FFT window time.
-The reception was better over high conductivity terrain. For example reception was better over a river than a shirt distance from it.
-The experiment showed that it’s possible toget positive results from cheap and simple amateur equipment.
-The ferrite ring autotransformer has proven itself. It was cold even during continuous power for long periods of time.
This is the first amateur transmission on VLF from Poland which has been received in another country. This is also the record distance for a transmission using a ground dipole antenna – over 1330 km.
This is probably the first VLF signal which has been transmitted from Poland after World War II. We are not aware of any military or other transmissions. Before the war we had the Babice Transatlantic Radiostation (callsigns AXO/AXL/SPO/SPL), which was similar to Grimeton/SAQ.
Stefan DK7FC transmitted at 6 aptil 2019 20:25 UTC at 2970.1Hz. The TX power was 487W into a 1130m ground dipole antenna. The ebnaut transmission parameters were:
f = 2970.1 Hz
Start time: 06.APR.2019 20:25:00.3 UTC
Symbol period: 6 s
Characters: 7
CRC bits: 16
Coding 16K21A
Antenna current: 2.4 A
Duration: 02:04:48 [hh:mm:ss]
The signal was received by Jacek / SQ5BPF in Warsaw/ Poland KO02md, at a distance of 976km!
After the filtering and noise blanking was optimised, the signal could be decoded:
sq5bpf@jitter:/stuff2/sq5bpf/vlf_stefan2$ vtcat -p ../vlf_stefan2/pliktmp6
sq5bpf@jitter:/stuff2/sq5bpf/vlf_stefan2$ vtblank -v -d0.0007 -a20 -t 50 DK7FC/P]
carrier phase: -10.6 deg
carrier Eb/N0: -0.4 dB
carrier Es/N0: -15.33 dB
carrier S/N: 15.63 dB in 133.5 uHz, -23.11 dB in 1Hz, -57.09 dB in 2.5kHz
elapsed 92
Due to the ongoing (on 20 august 2019) rescue operation in the Wielka Śnieżna Cave in the Tatra mountains we decided to write about cave communications.
Thailand Heyphone
Rocks and soil attenuate radio signals well. Despite of this some means of communications in caves and mines are needed.
The attenuation rises with frequency. Normal VHF communications gear can’t be used, sometimes the distance can deteriorate to meters, depending on the geology and shape of tunnels. Of course cell phones are totally out of the question too. Shortwave radio behaves only a bit better.
Much larger distances can be achieved using low frequencies.
Cavers have observed that sometimes it is possible to receive strong long and medium wave radio stations.
The Molephone designed by Bob Mackin in the ’70s was one of the first devices that enabled voice communications through rock. Unfortunately the schematics are not avaliable. This device used SSB on 87kHz. The antenna was a multiturn loop with about 1m diameter.
Since that time most devices use 87kHz USB (or DSB) to be compatible. The most popular are Heyphone and Systeme Nikola. Usually the power is in the order of 10W to keep the weight of the equipment and power sources low.
Heyphone
The Heyphone was designed by John Hey G3TDZ. Full documentation is avaliable so that anyone can build this device.
The Systeme Nicola was designed by Graham Naylor. It is very popular in France. This device has many versions. The last version Mk3 uses DSP techniques. Documentation for the Mk2 version:
At the begining multiturn loops (big coils) were used as antennas. The magnetic field from the transmitter coil could be detected by the receiver coil. Various sources state that voice communication at 150-180m distances are possible at power levels around 10W at 87kHz SSB. These antennas are still used for through-the-earth radiolocation to find the location of a transmitter in the cave (for cave mapping etc).
Experiments have shown that a ground dipole performs much better than the loop. With 10W power voice communication at 500m can be acieved (some sources claim 800m).
It is interesting that the antenna also works when the antenna ends aren’t grounded. In this case the connection can be made using “capacitance hats” from a few wires connected to the end. The connection is via capacitance to ground. Of course this degrades performance, but communication is possible.
Other means of communications in caves
Telephony using two wires, or one wire and earth return can be used.
According to tvn24.pl “On sunday a team started laying a cable which will be used for communications in the cave.”, so probably telephony will also be used in the Wielka Śnieżna Cave rescue effort.
During the 2018 Tham Luang Nang Non Cave rescue operation in Thailand VHF radios with mesh networking were used. Any radio can relay traffic to another radio. Of course this doesn’t work through rock, but can extend communications range in tunnels.
– A generator based on an old terminal; with an x86 processor, which had a uBlox Neo-7m GPS installed inside. The GPS is connected to the terminal serial port for control, and to use the GPS output for a coarse time reference (this is not very precise because the 1PPS signal is not connected). A 20kHz signal from the gps is connected to the sound card in the terminal and is used as a reference for Paul Nicholson’s excellent 
