Reception of the historical VLF-Transmitter SAQ Grimeton / Sweden.
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Hello everyone!
This is a short report of my activities, to receive the transmittion of the historical Verry Low Frequency-transmitter
"SAQ" in Grimeton / Sweden.
You can find a lot of information about SAQ on the internet, for example on the SAQ website:
https://alexander.n.se/
or on wikipedia:
https://en.wikipedia.org/wiki/Grimeton_Radio_Station
The most important part is the antenna. I chose a magnetic loop antenna, because it is the least sensitive to interference:
Matched loop-antenna with pre-amplifier.
I designed the preamplifier input with high impedance. There would also have been the possibility of decoupling the signal from the loop at low impedance using a coupling loop,
but with the high-impedance input of the preamplifier I have the option of also using an E-field antenna. This works quite well, but is more sensitive to interference.
The circuit diagram, with FET preamplifier and coax driver.
The pre-amplifier for the loop antenna has a separat housing, so that I can also use it for capacitive antennas.
As the receiver I chose the direct-conversion principle.
To recorde the Morse-code, I build a historic inspired line recorder:
I cut the paper stripe out of a cash register roll using a small homemade device.
December 3rd, 2023:
I build the receiver electronics in modules:
- crystal oscillator specifically for SAQ
- VFO for manual station select in VLF-band
- mixing down unit
- LF unit
- signal detector to control the line recorder
I also set up a small test transmitter.
Sum technical details of the test transmitter and local oscillator:
The frequencies are based on 8 MHz TTL oscillators. The divider chains are:
Test-transmitter: 8 MHz TTL-Osc., :5 (74LS90), :3 (HEF4017), :31 (HEF4024, HEF4081) = 17,2043... kHz
LO: 8 MHz TTL-Osc., :5 (74LS90), :7 (HEF4017), :7 (CD4017), :2 (CD4013) = 16,326... kHz
klick for video!
December 15th, 2023:
Here is the circuit diagram of the receiver:
The circuit diagram is based on a publication by DL1STO:
https://opppf.de/SAQ-Grimeton/index.html"
But I adaptet it to my requirements.
And the circuit diagram of the local oscillator with the VCO of the CD4046.
December 17th, 2023:
Now things are starting to get exciting, only a week left. That's why a first "field test" with all components was scheduled on our terrace:
Video first field-test:
Video "short and long strokes":
December 22th, 2023:
SAQ's test broadcast was announced for today, shortly after noon. A few fiends were with me, one with Morse knowledge.
Around 1:20 p. m. a clear and quite strong signal appeared and after a short adjustment its frequency few "...-" ("v") followed by "-.. ." ("de")
and the call sign "... .- --.-" ("saq") had to be recorded :-). We didn't expect such a clean signal.
Here is a short MP3 recording of such a sequence:
2023-12-22-MP3:
That was the first success. In the further course, the Christmas message transmission was for the morning of December 24th at 8 a. m. UT, that means 9 a. m. our time announced.
Unfortunately my line recorder didn't work. Because of other singnals, especially submarine communications, SAQ was not dominat enough.
For the future I need to add a sharper LF Filter. On the 24th I will record the Christmas message with the MP3 recorder and translate it "offline".
December 24th, 2023:
I got up early that day to have my reception system ready on time. The broadcast of the Christmas greetings began promptly at 9 a.m. CET.
Here is the MP3 recording of the message:
2023-12-24_2.MP3:
The signal was not as good as during the test broadcast two days earlier. Nevertheless, the content should be understandable if you can "read" it... ;-/
But that's why we have the screenshot from the SAQ website:
(permission for this is available)
You can also watch a recording of the broadcast on YouTube:
For YouTube broadcast
click on the image or this link.
(Not much happens in the first 5 minutes, you can safely skip them)
Here is a screenshot of my confirmation of receipt of the "SAQ Listener's Report Map" from their website:
And the link to the “SAQ Listener's Report Map”:
Click here for "SAQ Listener's Report Map"
(For my confirmation of receipt, click on the dark blue marking near "Heinsberg")
Then a comment about what I would do differently given my current experience:
Actually I don't have much to list here, it worked largely as I expected.
However, I would avoid the quartz-controlled local oscillator.
The VFO with 4046 is stable enough and the frequency setting for SAQ worked great with the small test transmitter.
So, at the end, of course, the E-QSL card also belongs here, as it has now arrived:
In any case, the whole thing was a great project and I will definitely continue to try to receive the messages from this very special station.
Many thanks to the SAQ team! I think it is important that such unique witnesses to the history of technology are preserved.
Alexanderson-Day 2024 on June 30th.
SAQ sends a greeting message on VLF twice a year. This is on the one hand at Christmas and on the other hand on “Alexanderson Day”.
This day is celebrated in memory of "Ernst F. W. Alexanderson", the Swedish-born builder of the VLF network and thus also the Swedish station.
The day always falls on a Sunday in June or July and in 2024 it fell on June 30th. So the program for this day was set for me :-).
Test transmissions from SAQ had already taken place on the Friday before, June 28th. Since I had other activities, I couldn't be on call all the time
and so I missed that opportunity. However, I had set up my reception system and I was also able to receive the usual "buzz" of submarine communication.
Unfortunately, due to the weather, the disturbance level was relatively high; a lot of cracking noises could be heard due to heavy thunderstorms.
Here is my setup for the reception:
Two programs were announced for Sunday, one for 11 a.m. and another for 2 p.m. CEST. Every broadcast requires a certain
amount of time to adjust the frequency and so I was able to receive the test sequence beforehand, consisting of repeated
"CQ DE SAQ" and the following "V":
Here is a short recording of the "run" before the first broadcast:
2024-06-30_adjust.MP3:
The actual greeting message followed promptly at 11 a.m. Here is the recording:
2024-06-30_message.MP3:
And of course the screenshot of the message from the YouTube live broadcast, which I was able to follow at the same time:
Of course I also listened to the broadcast at 2 p.m., followed it on YouTube and recorded it.
In any case, it was nice to listen to the historic station again and I will try to continue following the programs in the future.
My thanks go to the SAQ team for maintaining and operating this unique technical monument!
Anniversary of the first commercial broadcast exactly 100 years ago on December 1st, 1924.
On Friday, November 29th, 2024, test transmissions for the 100th anniversary took place two days later. I was able to do the first
received and recorded from three transmissions. The signal was weak, with lots of interference, but legible.
Here is a short recording:
2024-11-29_13h30_test.MP3:
Of course I was there on Sunday morning too. Unfortunately I couldn't hear the signal this time :-(. Also the
otherwise clearly audible submarine communications signals could not be heard.
My reception chain was still set up unchanged from the reception of the test broadcast on Friday. The battery for the
receiver was freshly charged and I swapped the preamplifier battery for a fresh one as a test. Everything has nothing
used. I assume that the atmospheric conditions were unfavorable for my location this time. That's just it
That's what people had to deal with 100 years ago, but without our current technical capabilities.
Well, the next show is at Christmas and I'll be there again :-).
test transmission on Friday, December 20, 2024.
On Friday, December 20, 2024, test transmissions were made for the Christmas message on the morning of Christmas Eve
on December 24, 2024. I was able to receive the frequency tuning and the subsequent loop of "V"s and the SAQ call sign
from 2:05 p.m.
Here is a short recording:
2024-12-20_ab_14h05.MP3:
Of course I will try again to receive the Christmas message on December 24th from 9am CET. So "stay tuned!"
mail: reinhard.lauterbach[at]freenet.de