dinsdag 25 december 2018

SAQ Transmission

Yesterday morning early I listened to the Christmas Eve morning transmission of SAQ. This Swedish station was built in 1924 to transmit messages in Morse code to North America. SAQ transmits a few times a year at a frequency of 17.2 kHz.

Antenna set up
About twenty years ago I made a large loop to listen to VLF stations. The loop consist of a cable of 5.6 meters with 12 wires, that are connected is series, to get a strong signal. A loop amplifier of a FET and a bipolar transistor pick up the signal of the loop.
The signal is fed back into the loop to  increase the Q-factor. With a 10-turn potentiometer I can adjust the Q-factor. I can even run the loop smoothly into oscillation. Which is really great to determine the resonance frequency.
The signal of the loop amplifier is fed into a frequency converter, built with a SO42p. I listen to the signal on my FT-817.

VLF Loop antenna in the shack - PA1B
My main objective of the morning was to first tune the loop.
After that I would write down the message, that was to be transmitted in CW (morse code).

The tuning was an immediate success. When I heard SAQ transmitting   vvvv SAQ  I started tuning by placing and removing capacitors with different values.  I ended up with 3 capacitors in parallel. 47 nF, 43nF and 8.2 nF. Yes, I don't know were it came from, but it is really 43 nF. Hi.

The signal was strong, I give a 579 by ear. I did not look on the S-meter.

Paper --> Dead circuit
After tuning, it was time to make room for a paper, to write down the message, that would be transmitted.
When I moved the breadboard with the loop amplifier about an inch, the circuit went dead. When I moved the circuit back, I heard the signal again. Then I let go of the circuit. It went dead again and whatever I did, it would not come alive again. OOPS. I still don't know what it is. I found one loose wire. It was the white wire in the picture below, but that was not the only problem. So I missed the message.

Terrible for a while
At first I felt terrible, but later that day I realized that, I did what I wanted to do. I had easily tuned the loop and I heard how loud the signal was. So I could give a report.
If it would happen to someone else, I would say: "Well, you have a great story to tell."

Loop amplifier on a breadboard - PA1B

zaterdag 17 november 2018

Merwede kanaal

Het is als weer even geleden.
Eind mei zijn we vanaf Vianen langs het Merwede kanaal gefiets, tot aan de Zwaankuikenbrug, waar deze wegwijzer staat.
Het Merwede kanaal is een mooi kanaal geflankeerd door bomen.
Ik heb hier ook wel gevaren met de kano, toen ik nog dakdragers had om de kano op de auto mee te nemen.


woensdag 24 oktober 2018

Special transmission of SAQ

More than 20 years ago I built a active loop antenna for VLF.
I listened from 100 kHz down to 20 kHz.

Today there was a special transmission in CW of SAQ from Grimeton in Sweden on 17.2 kHz. The transmitter is a generator that makes a power of 200 kW with a frequency of 17.2 kHz. The station has a huge antenna. The station was used 100 years ago to send messages in CW to North America.

My loop antenna is made of a cable with a length of 5.5 meters with 12 wires. The wires are connected in series. This inductance is tuned with a capacitor. The signal of the loop is picked up by a FET, followed by a bipolar transistor, that form a follower.

Placing the loop in the shack was easy. But then I had to remember how to connect the wires of the loop to the loop amplifier. Luckily I found the schematic in the article, that I wrote for the spring issue of 1997 of SPRAT. With the schematic I connected the 3 wires of the loop to the loop amplifier.

The Databuch 1980/81 Integrierte Schaltungen für die Unterhaltungs-elektronik of Siemens gave the information on the SO42P mixer, that I use in the frequency converter. After more than 20 years I could not remember which pin I used as an input. But with the book and a magnifying glass, I could connect the coax between the amplifier and the converter to the right pin.

Loop amplifier and frequency converter
Then I tested the frequency converter. On the oscilloscope I could see, that the oscillator was running and I could hear the carrier on 8 MHz on my receiver. So now it was time to tune the loop. I can drive the loop gently into oscillation to determine the frequency with the oscilloscope. With a capacitor of 47 nF my loop was oscillating on 25 kHz. I calculated that I would need a second capacitor of 47 nF in parallel for 17.2 kHz. But in my boxes of capacitors, there was only 56 nF, so with the extra C the loop was tuned to 16.6 kHz and I started listening. A quick look at the clock showed the transmission of SAQ had already started.

At first I heard a strong crackling (gekraak), but when I tuned the receiver I heard a weak CW signal. With the very strong crackling I could only copy a few letters.
I only managed to copy:  ork  gor  ba  l c pe c n  
But then I realized, that this noise source must be very close, because of the strength of the noise signal. Well my loop ran less than an inch from my Led lamp, that is placed on the oscilloscope. 

I disconnected the LED lamp and the band was quiet. Now I could copy the last part of the transmission about the QSL policy of this transmission. The transmission ended with QRU DE SAQ  SAQ  SAQ  SK

The next transmission of SAQ will be on the 24th of December 2018. If I start in time, to build up the circuit, I will be able to tune the loop precisely.  And I will have time to adjust the Q of the loop for the best reception. hi.

vrijdag 21 september 2018

Veron HF day meeting

This year I attended the Veron HF-day because of the interesting readings together with Henk PG7H. I was surprised to meet a fellow blogger, Bas PE4BAS. We met Bas PE4BAS and Tjip PD2TW, who had made the long trip to Apeldoorn. Bas and I had a lot to talk about during the lunch that we had later.

Bert PA1B and Bas PE4BAS 
I very much liked the two readings about the Aleksander alternator transmitter in Grimeton in Sweden by mr. Ola Hernvall.
I enjoyed the interesting reading about FT8 by Jan DL1JAN. Later it was great fun to see Jan, presenting a small quiz in which he accidentally, showed the answers before the questions. (hi). Luckily Jan shows a great resilience.
We applauded for Bas for reaching the 2e place in the PACC in the Low Power category. FB. But what I call low power, is very low power to the rest of all amateurs. Hi.
Further there was an interesting reading about working DX. It was interesting to hear how the DX stations, try to pick up also QRP stations.

woensdag 27 juni 2018

36 dB Attenuator of PA2ZZ

I received an email of Henk  PA2ZZ. He has successfully built the 36 dB attenuator. Henk wrote that attenuator works great. He uses the attenuator for WSPR with his K3 and a MFJ-loop.
I asked Henk for photo's of the attenuator.
Here they are.

36 dB Attenuator built by Henk PA2ZZ

The Attenuator 20 dB - 10 dB  - 3 dB - 3 dB of Henk PA2ZZ

The Attenuator 20 dB - 10 dB  - 3 dB - 3 dB
Thank you, dear Henk for the beautiful pictures.

donderdag 14 juni 2018


There was enough activity on the band in the
CQ WW WPX CW contest 2018.
But not as good as last year, because of QSB.

I made 39 QSO's on 14 MHz and 2 QSO's 21 MHz.
I used S&P in all QSO's.
My antenna is an End Fed.

The conditions were to bad for the power levels, that I use to work with.
The signals were not that strong and there was QSB.

Sometimes, by the time no other station called, and finally the frequency was clear. . . the QSB kicked in.
This is obvious a way to improve your operating skills. hi.
In this contest I did not make even a single QSO with less than 360 mW.
And by times 800 mW or 3.6 W was not even enough.
The loudest signal I heard was S9 +10 dB, but I needed 360 mW to answer, in stead of the usual 36 mW. hi.

Last year I could make 2 QSO's with 3.6 mW.
Well, I did enjoy the contest.

dinsdag 24 april 2018

Russian DX 2018

I had great fun with very low power in the Russian DX contest 2018.

I made more than 30 QSO's on 14 MHz and 2 QSO's on 7 MHz.
The propagation was good, so I could reduce my power when the S-meter goes up.
I used S&P in all QSO's.
For a power of less than 360 milliwatt, I use the PA1B attenuator to reduce my power.

I very much enjoyed the QSO with RT6A.
The signal was about S9+20dB, so I could reduce to 3,6 mW.
I was very lucky, because I heard RT6A 15 minutes earlier, but 10 dB less strong.
But at that time, many stations were calling, so my modest signal could not be heard. hi.

RDXC 2018 by PA1B

zondag 25 februari 2018

UBA DX CW contest

When I came on the band on 20 m, I heard a UA3 station with an ear splitting signal of S9 + 20 dB. So my first QSO I could finish with just 8 milliwatt, using the PA1B attenuator. WOW.
Friday before the contest the contest, I repaired the support for the antenna. My simple mast was damaged by storm. It was sunny, when I went onto the roof. Just in time for the UBA DX CW contest.

My antenna is an end fed that is fed via a 300 ohm twin lead. The twin lead acts as a counterpoise and acts as an impedance transformer. The end fed is sloping down to the east.

I made 20 QRPp QSO's with 800 milliwatt or less and 14 QRP QSO's with 2, 3 or 4 Watt.
QSO's in red in the table are more than 1000 Miles per Watt QSO's
All QSO's are made with search and pounce (S&P). My CQ with 800 mW gave NO response at all. hi.
UBA  DX CW contest 2018 PA1B

woensdag 17 januari 2018

Daily changes in propagation on 472 kHz

WSPR reveals the daily changes in propagation. It is not a surprise to see that in the 472 kHz band most spots are made during the night. As you can see most spots are made in the hour of 23 UTC and 00 UTC.
EA3IW WSPR on 475 kHz with 200 milliwatt with a 4 x 15 meter loop

Click on the table to enlarge.

maandag 15 januari 2018

EA3IW WSPR on 472 kHz with 200 milliwatt

Albert EA3IW made WSPR spots on 475 kHz over a distance up to 1900 km. Albert uses a square loop of 4 x 15 meters with 2.5 mm2 Cu wire. The antenna is small relative to the wavelength. Because of this the efficiency of the antenna is low.
Calculations show that the radiated power is about 200 milliwatt.
The spots were made from 26th of December 2017 till the 6th of January 2018.

To reduce the length of the table, I only show the data of the receiving stations, that reported during all of the days that are shown in the table

The lower the calculated lowest possible power, the better the propagation. The columns at the right show the spots with the strongest signal. (10 dB over 3 columns)

EA3IW WSPR on 475 kHz with 200 milliwatt from a 4 x 15 meter loop
The WSPR signal was heard up to 1900 km.

In the table the stations are sorted by distance.
The column of 200 mW shows the spots that were just strong enough to be decoded. The column of  20 mW and 2 mW show the spots that were 10 dB stronger and 20 dB stronger. The lower the Lowest possible power the stronger the signal.

EA3IW-3 is a receiver at a distance of 100 km of the transmitter of Albert. The table shows that in 130 spots the full power of 200 mW was needed to be heard. 205 Spots could have been made with 100 mW and 5 spots even be received if they were made with 20 mW.

The spots of  EA2HB show a dynamic range of 16 dB, from 5 mW to 200 mW.

The most sensitive station is F6GEXThe one spots with the strongest signal, could have been made with 0.5 mW. Notice that 262 out of 1126 spots, received by F6GEX, could have been made with 5 mW.  The difference between the spots with 200 mW and the strongest spot (0.5 mW) is 26 dB.

The results show that it is possible to use WSPR with a low power even on 475 kHz.
The changes in propagation are best seen, when you run WSPR 24 hours a day.
Thanks to Albert, for the interesting low power results and the pictures that I received.

Click to discover how to calculate the Calculated lowest possible power.

dinsdag 2 januari 2018

Cylinder dipole

The cylinder dipole with two Monster energy drink cans and a coil is easy to build and is working fine on 15 m. With 2.5 % of a wave length, it is very small antenna, that can be easily used indoors.
Building and operating with the cylinder dipole is not as difficult as it seams. There are no critical parts or critical procedures.
I wish you good luck, but most of all to have fun

I have writen a description on my website
about the Cylinder dipole
(Click to visit)