zaterdag 28 maart 2015

K5MQ WSPR 100mW on 40 Meters (2)

Dave K5MQ has been running WSPR for 4 days at 100 mW output on 40 meters.

To show the behavior of the propagation from day to day, I made a overview for four days.
This analysis uses the same data as Blog entry of yesterday, but also shows the relative signal strength of the received signal.

Horizontally you find the time in UTC in blocks of 1 hour.
Each rectangular black block indicates an hour, in which one or more spots occurred and the calculated lowest possible power of that spot(s).
Vertically you find the lowest possible power, which is a good indication of the signal strength.

The lowest possible power is calculated from the power of the sending station and the SNR of the receiving station. The higher the SNR, the better the propagation and the lower  the lowest possible power.
The lower the lowest possible power, the better the propagation.        

Please notice, that not all patterns in this propagation diagram,
can be easily recognized and can be easily explained. hi.
Propagation diagram. K5MQ WSPR on 40 m with 100 mW.
Propagation to WB5WPA over 500 km
Dave 's signal was received by WB5WPA over a distance of 500 km at 13 utc on the 24th with a calculated lowest possible power of 1 milliwatt.
From 13 utc on the signal becomes weaker. At 18 utc the signal is 10 dB weaker.
From18 utc to 1 utc on the next day, the process is reversed.
At 1 utc the signal has the same signal strength as at 12 utc of the previous day.

For the distance of 500 km we can see, that when the signal is reflected
in the ionosphere, the propagation is immediately at it's best. 
From that moment, the signal will be weaker, until the process is reversed. 

Propagation to N8SDR over 1100 km
On the 24th we see the same pattern in the propagation, but this time throughout the night, between 3 utc and 10 utc. At 3 utc the signal suddenly appears and is immediately very strong . Than rapidly becomes weaker (16 dB) and than gradually becomes stronger again, to reach the highest value at 10 utc.

Electrical field strength
Dave noticed that K9AN at a distance of 1003 km copied his 100 mW throughout the daylight hours, many times.  And that he must have a great receiver there.
To compare the signals of the different stations I made an analysis of the received signals by the Electrical field strength in micro Volt per meter.
The analysis below shows that K9AN, N8SDR and KE7TYT received Dave's signal with the same field strength. hi. The difference between each of the columns is 5 dB.

A calculated lowest possible power of 1 milliwatt means that a signal of 1 mW,
could be received with a SNR of -29 dB.

vrijdag 27 maart 2015

K5MQ WSPR 100mW on 40 Meters

Dave K5MQ reports on his blog, that he has been running WSPR for 4 days at 100 mW output on 40 meters.  He wanted to try lower power on 40 meters, than he did on 160 m.

The analysis shows the stations, that spotted Dave for 3 days or more.
Under UTC you find the number of spots from hour to hour.
E.g. K9AN was spotted 3 times on 2015-03-22 between 23:00 and 23:59 UTC

Futher, I also chose to show two stations with the largest distance.
KL7L from Alaska and EA/LA3JJ from Spain.

WSPR spots of Dave K5MQ on 40 m with 100 mW

donderdag 19 maart 2015

Peters QSO's with 5 milliwatt

Are you curious how Peter DL3PB made these amazing QSO's, with an 
All diode transceiver with just 5 milliwatts on 15 meter, then read this
informative e-mail from that I received from Peter.

Hello Bert,
Glad to hear from you and thank you very much for posting my latest milliwatt results on your blog and the kind comment - I like especially the stamp-sized logos for each entry – nice work.

The original version, as posted in February 2012 (was 2 mW / 20m band) allowed some minor DX
e.g. EA8 or 5B4, but within three years,  I could not make a single contact beyond the usual one-hop distance.

Finally I came to understand, how the efficiency of the parametric VXO could be improved:
all I had to do, was to insert two small inductors in series with the varactors
once you got it, it’s all so easy...with now 5 mW on 15m band some real DX leaped into view.

Not sure, whether it’s about the somehow higher power now or the different band,
The more or less first serious attempt in the Black Sea contest was rewarded with a
first transatlantic QSO with Randy/N1KWF and the ARRL-DX contest two weeks later,
was good for another one into NJ with John/W2ID at 6050 km.
John had lot of fun with my exchange ( 599 001 ) and replied with something like 
hi ur pwr 1W fb” –
I didn’t dare to tell him the truth, because of the heavy QSB.
These two OMs must have excellent ears and actually they did most of the work.

I’ve attached a schematic (Click) with a better resolution ( .bmp ) than that on,
but of course it’s up to you, whether or not you want to post that, which will require to edit the text a bit.

Will make some more photos, when I got it into an enclosure, but that will take some time, the TRX
is still under construction and I want to maintain its multiband capability, so far I’ve tested 17m and 15m, but 12m should work as well, but that requires careful planning.

Again, many thanks, Bert – keep your great blog going.

Tot ziens!


zaterdag 14 maart 2015

Pi Day

Pi = 355 /113

As a teacher in electronics I use this accurate fraction for Pi,
when I use a calculator without a key for Pi.
I have been looking for a fraction with one or two prime numbers.
I came up with 113 as divisor, which is a prime number.

The numbers are easy to remember.
The accuracy is better than one millionth. 10-6.

maandag 2 maart 2015

5 mW All diode TRCV crosses the pond

This winter Peter DL3PB built a new version of an
"All Diode" transceiver, the Paraski.
The new transceiver works on 15 meter and has an output of 4...5 mW

For Peter a dream comes true, by crossing the pond with milliwatts.
Peter  made a few QSO's with 5 mW, into an EFHW vertical on 15 m.

Peters rig has only diodes in the amplifiers and oscillators.
It's amazing, even for a milliwatter as myself. WOW.

Please visit the QRZ page of Peter (Click) to look at the schematic and a photograph 
of the Parasaki for 15 meter.

Data on the drawing:
PWR OUT 4...5 mW

See the post of the 8th of February 2012 in this Blog,
for the 20 meter, 2...3 mW, Parasaki, all diode transceiver built in the winter of 2011 by Peter.

zondag 1 maart 2015

UBA DX contest 2015

This weekend I participated in the UBA DX contest.
The conditions were not very good , but I still made 27 QSO's with S&P in CW.
I could make 1 QSO with less than 100 mW, 3 QSO's with 800 mW.
The rest of the QSO's was made with 3 or 4 watts.

Rigth at the start, I heard YT1A.
Vladans signal was very strong, so I reduced my power.
With the FT-817 set to 800 mW and with the "PA1B 40 dB step attenuator" set to 10 dB,
the power to the antenna is reduced to 80 mW.
With a distance of more than 900 miles, this results in more than 11000 Miles/Watt.
This was the only QSO with less than 100 mW in this contest.

After that I made QSO's with 800 mW to 4 watts.
The FT-817 here gives less than 5 watt with full power, after a serious mismatch.
This is less than 4 watts on 14 MHz or less than 3 watts on 21 and 28 MHz.

The ribbon of the Inverted V is not yet repaired.
As long as there is no wind, all is OK . See the post on the PACC 2015 Click.
But with a wind force of 6 on the scale of Beaufort , it was not always easy. hi.