dinsdag 20 januari 2015

De stad in MIJ

Bern en de Alpen  detail  (Click)
Vorige week ben ik naar Museum IJsselstein geweest.
De tentoonstelling: De stad in MIJ toont de bebouwde verbeelding.
Schilderijen, bijzondere 360 graden foto's, wandkleden en objecten.

Fascinerende stadslandschappen
Ik werd verrast door de zeer gedetaileerde stadstekeningen van
Stefan Bleekrode. (Klik voor het artikel in het AD)
Vooral Bern en de Alpen vind ik heel bijzonder
Ik ben bijna in de tekening gekropen, om alle details zoals schoorstenen, dakkapelllen en hun schaduwen goed te kunnen bekijken.
Zeer de moeite waard om te zien.

De stad in MIJ. Bebouwde verbeelding van realistisch tot utopisch.
Museum IJsselstein. Nog te zien t.e.m. 15 maart 2015.

Bern en de Alpen   Stefan Bleekrode

zaterdag 3 januari 2015

WSPR Propagation Analysis - G3XBM 28 MHz Dec 2014 (2)

The propagation changes from day to day, as can read in the blog of Roger G3XBM.

Here is an analysis of the WSPR spots of G3XBM that were received by K9AN 
on the 24th and the 28th of December 2014.  
The time is given in UTC.
The diagrams show a lot of spots, since K9AN listens every two minutes. hi

The lower the calculated lowest possible power, the better the propagation.
On the 24th, the propagation is at it's best around 13:50 UTC and 17:06 UTC,
with a calculated lowest possible power of 5 milliwatts.
 Click to enlarge.     G3XBM  received by  K9AN  on  2014-12-24
On the 28th the propagation has a short peak at 14:52 UTC.

Around that time there are seven successive spots, every two minutes.
In the spot of 16:36 utc, the full power of 500 mW is needed, to be spot. hi. 
G3XBM received by K9AN  on   2014-12-28
In most of the spots, the calculated lowest possible power is 50 mW or less, on both days.
This means that, if you would use CW instead of WSPR, that 1 watt (20 * 50 mW) could be used to make QSO's in CW.

vrijdag 2 januari 2015

WSPR Propagation Analysis - G3XBM 28 MHz Dec 2014

Roger G3XBM ran his WSPR signal for several days on 28 MHz.
This provides interesting information on propagation on 28 MHz.
I collected data from the WSPR database, to make the diagrams.

The first two diagrams, show spots that are collected over several days.
The strongest spots are given in red

The first two diagrams show the calculated electrical field strength in micro volt per meter.
If spots show the same field strength, the voltage on the antenna will be the same, 
for a simple wire antenna.
The difference between the successive values of the field strength is 5 dB.
This is about one S-point, since 6 dB is one S-point. 
The lower the value, the better the propagation.
So 0.03 micro volt/meter is about 1 S-point stronger than 0.06 micro volt/meter.

The strongest spot over 900 km was 2 S-points down, compared to the spot over 5300 km

The strongest (in red) spots show the same field strength.

Notice that the spots over 5300, 6500 and 14700 km were made with the same field strength at the receiving antenna, so the strength of the signal that arrived on the antenna  was the same in these three spots.

Further analysis shows which receiving stations have Excellent Ears. See the spots in red.
The spots in red in the table below correspond to the spots in red in the tables above.
The stations with excellent ears.
Power in CWI was wondering, how much power would be needed to make  CW QSO's.
For a CW QSO you need  (Click)  twenty times more power, than for a WSPR spot. (13 dB)
The diagram below shows the  (Click)  Calculated lowest possible power in milliwatt for each spot.

For the strongest WSPR signal, received by K9AN the calculated lowest possible power is 2 mW.
Thsi means that the that 2 mW would be received with a SNR of -29 dB. (Solid copy in WSPR)
To be received in CW, a power of 20 * 2 = 40 mW would be needed.
This does not surprise me a bit, since I made a CW contest QSO with K3WW on 21 MHz in 2012 with 36 mW.

Rogers signal was also heard in VK. The calculated lowest possible power was 5 mW.
So in CW his signal would be heard with 20 * 5 = 100 mW.
This seem too low, but please notice that to double the distance it takes an increase of 1 S-point (6 dB) to get the same field strength.
One  S-point means four times more power.
Further notice that WSPR is patient and tireless.
It is even possible that one of the operators was a sleep during the time that the spot was made. hi.

donderdag 1 januari 2015

CQ WW DX CW 2014

I had great fun in the CQ WW DX CW contest of 2014.
I had my inverted vee repaired just in time for the contest.

But most of all, I was very curious, how fast the
PA1B Fast and Accurate 40 dB Power Attenuator
would be in a large contest with enormous activity.

I am very happy with the attenuator.
As I mentioned before, the fast attenuator can be switched instandly.
So I am immediately ready to answer a CQ.

I started on 10 m and went to a lower frequency each time a band closed.
At times when the signals were getting stronger, I tried to use a lower power in the next QSO's.
On 40 m the band was too busy to use a very low power.
When I was on 40 m, the other bands were closed, so all other operators were also on this band.
So I made most QSO's on 40 m with 3.6 W. (Category less than 5 watts)

The inverted V works fine.
Since a long time I could make a few QSO's with less than 10 mW.
I used a power of about 4 watts down to 1.6 milliwatts.
The two QSO's in the column of  2.5 mW in the table were made with 1.6 mW and 1.8 mW.
(500 mW means more than 250 mW and less than 500 mW)

maandag 29 december 2014

The start of the CQ WW DX CW contest

23 dB   Click to enlarge
After repairing the Inverted V, I took part in several contests.
The first contest was the CQ WW DX CW contest.

I was eager to use the 
"PA1B Fast and Accurate 40 dB Power Attenuator
in a contest with a large activity.

In the first 5 QSO's were made with 3 watt to 400 mW.
After 5 QSO's the signals were getting stronger, so I could use the attenuator. With signals over S9, it was possible to make QSO's with a power of 72 mW and 36 dB.

The 18th QSO, with RM5A, was the first QSO below 10 mW with 7.2 mW. So this was very promising.

YZ7Z - 1.8 mW       RM5A - 7.2 mW 
The 19th QSO with YT7Z was made with 1.8 mW with the attenuator switched to 23 dB and the set on 360 mW.
An attenuation of 23 dB gives a power ratio of 1/200.

23 dB is 10 dB + 10 dB + 3 dB
The power ratio is 10 * 10 * 2 = 200
So the power is 360 mW / 200 = 1.8 milliwatts.

With one hand on the keyer and one hand on the switches of the attenuator, I can switch the power in a "milli"second.  Now I never miss an opportunity to answer. hi.

Immediately after each QSO I note the power of the set and the position of the attenuator in dB.
Further I calculate and note the power.

zondag 28 december 2014


Gisteren. op derde kerstdag, heeft het voor het eerst dit jaar gesneeuwd.
Vandaag hebben mijn vrouw en ik heerlijk gewandeld bij Rhijnauwen.

De sneeuw zorgt voor mooie plaatjes.

zondag 7 december 2014

PA1B Power Attenuators for QSO's

In the CQ WW DX CW contest, I used the PA1B fast and accurate 40 dB power attenuator for QSO's. During the contest I experienced that the attenuator is even faster than I expected.
I am very happy with this fast attenuator.

The attenuator has sections of 20 dB, 10 dB, 7 dB and 3 dB.
In most situations one switch is switched OFF and an other is switched ON, to increase the power with an step of 3 or 4 dB. Which makes the attenuator easy to operate, with one hand.
I experienced that with this attenuator, the power can be increased instandly.
So I am immediately ready to give my call again, with slightly more power.
PA1B Fast and accurate 40 dB power attenuator for QSO's            
Until now I used an attenuator of 10 dB or 20 dB and the adjustment of the FT-817 to set the power for QSO's with very low power. E.g. 50 mW. When I must increase the power of the FT-817, because my signal was not heard, I must push the botton of the menu to set thepower 3 times to double my power.
The time to change the power of the FT-817 is too long to be ready to answer the next CQ, when my signal is not heard.
But now I never miss an opportunity to answer.

Fast attenuators (click)

You find more, interesting  info on attenuators 
on my website: PA1B QRPp page (Click)

donderdag 27 november 2014

Inverted Vee repaired

300 ohm ribbon repaired
Today I repaired my inverted V antenna after a long time.
He is flying high again.
Before placing a new pole, I repaired the 300 ohm ribbon.
I smelled solder smoke for the first time in months.
The wear and tear on the roof had damaged one of the wires of the ribbon.

I glad I am in time for the CQ WW DX CW of this weekend

Doorvoer bij het dakraampje op zolder

maandag 24 november 2014

zaterdag 22 november 2014

Measurement of attenuattion

At the top of the Blog, I have changed my Page List by adding a page on
(Click) measuring the attenuation of an attenuator.

After building an attenuator, the attenuation can be easily and accurately measured with a DC voltage.  Voltages can meausred accurately with a digital voltmeter.

Measure the attenuation with a DC voltage

Example calculation
V1 is adusted to to 3.2 V.
V2 is measured as 0.99 V
A (dB) = 20 * log (V2 / V1) = 20 * log ( 0.99 / 3.2)
A (dB) = 20 * log (0.309) = 20 * 0.5095 = -10.19 dB
These values were measured for a 10 dB attenuator.

zaterdag 8 november 2014

10m WSPR - 5 watts from M0DEV

Mark M0DEV uses WSPR with 5 watts.
Today he made more than 400 spots on 10 m.
I noticed this since Mark left a note on the Blog of Roger G3XBM.

Mark notes:
Interesting. I am running 5 W (it's as low as my rig will go) and our two 3 hourly plots on wspr are all but identical. Neither of us has made any headway with the west side of the states.
The conclusion I draw is that when the band is open, it's open, and when it is shut it is shut: 
there is no point trying to blast it open with QRO.

The analysis below shows the calculated lowest possible power.
The lowest possible power is calculated from the power sent and the SNR.
The better the SNR, the lower the lowest possible power, the better the propagation.

The analysis shows that the propagation was good this day and confirms Marks statement that QRO is not needed.
Please notice that even with 100 mW, Marks signal would be heard over a large distance.

zaterdag 25 oktober 2014

Meeting of the BQC in Hardewijk

Vandag was de jaarlijkse bijeenkomst van de Benelux QRP Club.
Ik heb genoten van het programma en het ontmoeten van vele QRP vrienden.
Na het geplande programma kreeg ik de gelegenheid om over mijn
"Snelle en nauwkeurige verzwakker van 40 dB voor QSO's", te spreken.
Het was een zeer gezellige dag met een goed verzorgerde catering.
Tot volgend jaar. hi

woensdag 22 oktober 2014

10 dB attenuator for 5 W built by Stefano IZ1OQU

I received a very nice and very interesting e-mail from Stefano IZ1OQU.

Dear Bert,
I'm IZ1OQU and my name is Stefano, from Italy, and I'm writing you to thank you for the attenuators that you have so simply and clearly explained on your website.
I built one, 10 dB, for my SSB DXing activity. It's really fantastic and I wonder how people can receive me with 50mW SSB!
I tryed on 20, 12, and 10 m bands with same good results, with three top-qrb of 2300 kms (Russia, Finland and Georgia).
Everything under 2000 kms it seems easy to reach. I use vertical dipoles, so not that big antennas even though they are full-sized for their bands.
I'm gonna build a 20dB attenuator to reduce more!
Thank again for your job.
All the best '73
Stefano IZ1OQU

10 dB Attenuator for 5 watts built by Stefano IZ1OQU
In a further e-mail Stefano wrote:

I designed the 10dB attenuator for 5 W of max input power. 
5 W is the output of Yaesu FT817. 
You know: it has 4 switchable fixed power outputs: 0,5 W - 1 W - 2.5 W and 5 W.
With 0,5 W and 10dB attenuation, I can have 50mw. On 5 W, it falls to 500mW which is the standard low power - usually enough for many European QSO's.
The 5 W design let me switch on all the 4 power output even though it needs more resistors to handle the power. I could use bigger resistors of 2 W, but the only shop around here is not well supplied for values over 1/2 W. 

Stefano used the Power Attenuator Calculator from the PA1B QRPp page to design his attenuator.
This Calculator is developed to design Power Attenuators for 5 watts or more, built with resistors of a modest power, such as 1/4 W or 1/2 W.
I am very pleased to answer the questions that Stefano had.
Thanks Stefano for the questons.

vrijdag 3 oktober 2014

What is QRPpp

QRPpp is the (not official) term that I use for a power of less than 100 milliwatt.
Here is a nice diagram on QRPpp, QRPp and QRP.

How is it possible to use QRPpp?
Read the post QRPp How is it possible

zondag 28 september 2014

PI4AA is terug

Dankzij een enthousiast team van medewerkers,
is de Veron afdeling 't Gooi er in geslaagd,
de uitzending van PI4AA voort te zetten.

De uitzending is op elke eerste vrijdag van de maand 
om 21:00 uur op:
80-meter: 3605 kHz in LSB
2-meterband: 145,325 MHz in FM

Voor nieuws over PI4AA kijk je op de website: http://www.pi4aa.nl