zaterdag 20 april 2019

KX4AZ WSPR with 10 milliwatt

Last week I received a very nice e-mail from Bruce KX4AZ. He searched the net with "WSPR 10 milliwatt" and found the page on "WSPR with 10 milliwatt" on my PA1B website. hi.

Bruce KX4AZ is a operator that makes very interesting WSPR spots with just 10 milliwatt.

Believe it or not, but a WSPR station with 10 mW will ONLY be spotted, when the propagation is very good. Please study the diagrams below, to convince your self.

Lowest Possible Power diagram
To show the propagation, I developed the Lowest Possible Power diagram. You can immediately see how good or how lousy the propagation is, for each individual spot.
The better the propagation, the lower the Lowest Possible Power.

2019-04-19 I visited the WSPR old database and collected some interesting spots.

Time slot 1 
In the time slot of  17:46 UTC ND7M spotted 7 stations.
4 stations with 5 W, 1 station with 1 W, W6CLB with 100 mW and KX4AZ with 10 mW.
Luckily for Bruce, the propagation from the stations with 5 W and 1 W, to ND7M was not that good, so Bruce's signal was not over shouted by the 1 W and 5 W signals. Something that can easily happen, even with a power of 100 mW.
In the first diagram Bruce was spotted by ND7M with a SNR of -29 dB. It's the spot in yellow, on the line of -29 dB and the line of 10 mW. So in this time slot Bruce needed the full 10 mW. Hi.
In this time slot the best propagation is shown by the spot of W6CLB with 100 mW and a SNR of  -15 dB. This spot has a Lowest Possible Power of 5 mW. Thus about 3 dB better than the spot of Bruce.
KX4AZ with 10 milliwatt spotted by ND7M over 3100 km
Time slot 2
The second diagram shows the next spot of KX4AZ by ND7M
In this time slot the signals of W6CLB with 100 mW has a SNR of -12 dB.
The signal of KX4AZ has a SNR of -22 dB. please notice that both spots, show the same propagation, which is very good. The Lowest Possible Power of both stations is 2 mW. The signal of Bruce is even about 7 dB stronger, than in the first time slot.

KX4AZ with 10 milliwatt spotted by ND7M over 3100 km


woensdag 3 april 2019

eQSLs for 80 mW

It's great fun to make CW contest QSO's with very low power.
When the S-meter goes up, I lower my power accordingly.

In the last batch of eQSL's I found a 3 eQSL's that confirmed QSO with 80 mW.

  EA7TH   1151 Miles & 80 milliwatt gives 14390 Miles/watt

  
UB3A  1302 Miles and 80 milliwatt gives 16270 Miles/watt


YO3APJ     1088 Miles and 80 milliwatt gives 13600 Miles/watt

zaterdag 16 maart 2019

Vlieger

Onze kleindochter heeft vanmorgen op Scouting een vlieger gemaakt, van een stevig stuk plastic en een paar stokjes. Omdat het plakband op sommige punten al losliet, hebben we de bevestigingspunten verstevigd met breed en sterk plakband.
Het dwarsstokje verbetert de "vliegvaardigheid" enorm
Na een paar half gelukte vliegpogingen, hebben we een derde (dwars)stokje geplaatst, om de vlieger "open" te houden. Dit was een onmiddelijk succes.
De vlieger kon nu uit de hand opgelaten worden, zonder vrijwel onmiddelijk dubbel te vouwen.


In de lucht
De sterk wisselende wind vraagt echter heel wat vaardigheid van de "vliegenier".

Onverwachte duikvlucht
Het lukte opa om de vlieger, in sterk wisselde wind, tot zo'n 6 meter boven de grond, te laten opstijgen. Hi.

vrijdag 15 februari 2019

Here is an other analysis of a spot made by Paul PA0K on February 1st 2019. He was spotted by W4HOD over 7200 km with a SNR of -23 dB. This spot reveals, that the propagation, between Paul's station and W4HOD, was not good, at that moment. But never the less, Paul's signal was received, with a bit of luck, as we will see.

Spots sorted by propagation
The table shows all the stations, that were received by W4HOD in Alabama in the time slot of 13:12 UTC. I have sorted the spots by propagation, using the Lowest Possible Power (LPP). The lower the Lowest Possible Power, the better the propagation. The propagation to W4HOD was good, or even very good, for the first 9 stations in the table. This are the stations that have been spotted with a LPP of 50 milliwatt or less.

PA0K
The propagation from Paul's QTH to W4HOD was poor with a LPP of 500 mW.

PA1OSF
W4HOD also received PA1OSF over a distance of  7200 km from The Netherlands. PA1OSF was received with a LPP of 20 mW. The propagation from PA1OSF was 17 dB better than from PA0K. The distance between PA0K and PA1OSF is 71 km (44 mi). The difference can be caused by propagation, antenna direction and the antenna.


Spots received by W4HOD
The propagation between VE3KAE and W4HOD shows the best propagation with a LPP (lowest possible power) of 0.5 mW. Luckely for Paul, VE3KAE used 100 mW. Believe it or not, if VE3KAE had used 5 W, in stead of 100 mW, this signal would have used a large part of the dynamic range of the receiver of W4HOD and Paul's signal would probably not have been spotted.

Frequencies
I noticed that W4HOD received twice the number of spots compared other stations. In an analysis of frequencies that were used, I saw, that W4HOD can receive two signals a few Hz apart. This suggests that there are more than one WSPR receiver or detector at W4HOD.

Dynamics
The dynamic range of the SNR is +1 -(-26) = 27 dB.
The dynamic range in LPP is 1000/0.5 =2000, which is 33 dB.

woensdag 13 februari 2019

PA0K spotted by EU2AAH

Here is a further analysis of spots made by Paul PA0K on February 1st 2019. The propagation was not that good. But Paul's signal was earsplitting into Belarus. He was spotted by EU2AAH over 1500 km with a SNR of -3 dB. This spot reveals, that the propagation, between Paul's station and EU2AAH, was very good, at that moment.

Lowest Possible Power diagram
I developed the Lowest Possible Power diagram, to compare spots, that are made with different power. The Lowest Possible Power diagram shows instantly, how good the propagation is.
A spot is placed on the diagonal line of the power, that is used by the transmitting station. The height of the spot in the diagram is determined by the SNR of that spot. You can read the Lowest Possible Power of a spot, on the horizontal axis.
The better the propagation, the lower the value of the Lowest Possible Power.

Spots by EU2AAH
This diagram shows all stations, that were spotted by EU2AAH in the time slot of 13:52 UTC. It can be seen instantly that 3 station were received with good propagation and 2 with very good propagation. The letter gives the DXCC of the spot.
Paul's signal (PA0K) was the strongest signal, with a SNR of -3 dB. The arrow to the horizontal axis points to a  Lowest Possible Power of 5 milliwatt. The LPP of 5 mW is in the area of  very good propagation.
The propagation between F6KOP (F in the diagram) and EU2AAH is even better, with a LPP (lowest possible power) of 2 mW.

Lowest Possible Power diagram of spots received by EU2AAH
The line of 10 milliwatt
The dashed line in the LPP diagram is the diagonal line for a power of 10 milliwatt. PA0K and F6KOP could also be spotted if they would use a power of 10 milliwatt. If PA0K would reduce from 2 Watt to 10 milliwatt, his signal would be received with a SNR of -26 dB. F6KOP would be received with a SNR of -22 dB with a power of 10 milliwatt.

Table of spots received by EU2AAH
This is the table, that I used to draw the LPP diagram.

zaterdag 9 februari 2019

Very Good Propagation with WSPR

With this table you can immediately judge the propagation from your WSPR spots.
For example, when your 1 Watt WSPR signal is spotted with a SNR of  -9 dB,
or higher, the propagation is very good.
If you notice that the propagation is very good, consider to reduce your power.

Judge the Propagation with your WSPR signal
A WSPR beacon with a power of 10 milliwatt, will ONLY be spotted, when the propagation is very good. WSPR with 10 milliwatt can be compared with a CW beacon with a power of  200 milliwatt.

donderdag 7 februari 2019

Good propagation for PA0K

My fellow Blogger Paul (PA0K) used WSPR for an hour, on on February 1st 2019. His 2 watt WSPR signal has been spotted 31 times, in one hour. For Paul the most interesting spot was made by W4HOD, over a distance of 7200 km. In many spots you can see, that the propagation was not that good.

I noticed an other very interesting spot, that was made by EU2AAH over 1500 km. Paul's signal was earsplitting into Belarus. When I made an analysis of the spots, this spot came up, as the spot with the best propagation. This spot reveals, that the propagation, between Paul station and EU2AAH, was very good, on that moment.
To compare the propagation, I use  the Lowest Possible Power, that I calculate from the used power and the SNR. A Lowest Possible power of 5 mW, can be compared to 100 mW with CW or 2 watt with SSB. Thus very good propagation.

PA0K - WSPR spots with 2 watt on 20 meter
The table also shows that the propagation was good to TF3GZ on Iceland, R3TJP in Russia and EA8BFK on the Canary Islands.

The second table shows the propagation, in the successive time slots, in which Paul was transmitting.
Notice that, the better the propagation, the lower the Lowest Possible Power.

The spots made by R3TJP start with good propagation with a Lowest Possible Power (LPP) of 50 mW. In time slot 13:30 utc the signal is drops 10 dB with a LPP of 500 mW. In the last time slot the signal is up again to good propagation. LPP 50 mW.

The signal received by EA8BFK is first strong, with a LPP of 20 mW, but later the signal gets a bit weaker.

The signal that is received by W4HOD, shows a LPP of 500 mW in the first two time slots. In the time slot of 13:30 UTC the SNR is -29 dB, so all the power is needed to be spotted. Hi.

PA0K with WSPR on 20 mtr in 5 time slots
Thanks Paul, for the interesting spots.
Paul placed the tables, that I sent him on his Blog.

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).

Tuning
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.

Report
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.


Zwaanskuikenbrug



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

CQ WW WPX CW 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