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)