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

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:

vrijdag 26 september 2014

WSPR Propagation Analysis - G3XBM 28 MHz

Many WSPR operators jump from one band to the next, when band conditions changes.
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 this diagram.
In this diagram, I choose to show the spots of Roger received by DK6UG over 600 kilometer and LB9YE over 1500 km.
The diagram shows the number of spots for a day and from hour to hour.
The stronger the signal, the lower the calculated lowest possible power.

DK6UG over 600 km
It's interesting to see that the propagation to DK6UG changes from day to day.
On the 13th there are two peaks in the propagation, with no propagation in between.
On the 14th there is only a spot on 18 UTC.
This is at the same time of the peak of the day before.
On the 15th there are 3 peaks at 11, 14 and 19 UTC
The 17th is the most interesting day.
The day starts with reception on 11 till 12:58 UTC.
The 17th shows one very strong spot at 14:10 UTC with a calculated lowest possible power of 10 mW. The next spot with a CLPP of 1000 mW was on 14:54 UTC. Notice that in this spot the signal strenght is 20 dB lower.
Please notice that there is no reception from 13:00 till 13:58 UTC on all days,except for the 19th.

LB9YE over 1500 km versus DK6UG over 600 km
Most interesting are 13th and 14th
At the 13th the propagation is good to DK6UG, but not to LB9YE.
At the 14th it's the other way around.

vrijdag 19 september 2014

DL1DN - HF SSB QRPP QSO´s down to19mW

David DL1DN has send me a link for his very interesting video.

David made a video in which he reduces his SSB signal from 2.5 W to 19 mW, during a QSO
He reduces his power using an attenuator of 3 dB and 3 attenuators of 6 dB.

An attenuator of 3 dB reduces the power to 1/2.
An attenuator of 6 dB reduces the power to 1/4.

David starts with 2.5 watt (0 dB) and uses a homebrew multiband dipole at 1.9 m above the ground.

The next steps are:
Time          Attenuation         Pwr                Signal
0:15               0 dB                 2.5 W
1:30             -3 dB                 1.25 W             S6
1:42             -9 dB                 300 mW           S5
2:00            -15 dB                80 mW                         Video says:  -18 dB, but it is -15 dB.
2:14            -21 dB                19 mW             S4 or S3  

Please notice that every step of 6 dB is 1 S-point.
The receiving OM has an calibrated S-meter, which is excellent for this experiment.

The video shows what happens when the power is reduced.
David transmits but also receives through the attenuator.
Every time that David  reduces the power, also the signal of the received station is reduced, so you can hear for yourself what each step of 6 dB does.
As you can hear, listening though the attenuator is absolutely NO problem.

Click here:

Enjoy this very interesting video

For non German speakers:
Wahnsin  = madnes
Hintergrundpegel = back ground level

dinsdag 16 september 2014

Reparatie van de Numark NDX800

De NDX800 is een hoogwaardige controller voor de DJ met meerdere muziekbronnen. U kunt alles mixen met de NDX800. 
Het maakt niet uit of de muziek op uw computer, USB stick of CD staat! 
Dit digitale deck heeft het 'gevoel' en de indeling die u gewend bent. Natuurlijk wel met een beetje Numark-innovatie!

De NDX800 is echt een prachtig apparaat.
Maar zoals op internet te lezen is, gaan de schakelaars nog wel eens stuk
Zo ook bij beide apparaten van Sebastiaan, DJ SeppieJ.
Pijl bij de defecte START schakelaar,   Demontage,   STARTschakelaar verwijderd  en   Wachten op de nieuwe schakelaars.
Chef monteur Wendy heeft de apparaten open geschroefd, nadat ze op internet een video voor het vervangen van de schakelaars had gevonden en pa(1B) heeft de schakelaars vervangen.
Niets is zo erg als een haperende schakelaar.
Ik heb sinds lange tijd de soldeerbout weer eens opgestookt.
En een zeer tevreden Sebas, mixt weer als vanouds. hi.

zondag 14 september 2014

Fast and accurate 40dB Power Attenuators for QSO's on the PA1B QRPp page

Fast in QSO's
A simple way to reduce the power of your QRP set to milliwatt level, without modifying the set, is the use of attenuators.
The combination of 20 dB, 10 dB, 7 dB and 3 dB is fast to switch, when you want to increase your power in QSO's.
In one move, one attenuator section is switched OFF and an other is switched ON, to increase the power with a step of 3 db or 4 dB.

Last week the PA1B QRPp page was updated:

Click to read more about the interesting
PA1B Fast and accurate 40 dB Power Attenuators for QSO's.
Specially designed to use in QSO's with very low power.

vrijdag 12 september 2014

PC4T with 5 watts on 14 MHz with WSPR

In addition to the update of the post of 2014-09-08, I made a new analysis of the spots between made over a distance 1500 km to 2200 km.
The spots were made during the morning.

Leersumse veld

Bij het meertje Leersumse veld
Gisteren hebben mijn vrouw en ik eerst geklust.
Daarna zijn we doorgereden naar het Leersumse veld.
Vanaf een bankje hebben we de schaapsherder en zijn kudde gadegeslagen.
Het was heerlijk zonnig weer.

We zijn doorgelopen tot het meer en hebben daar heerlijk in de zon gezeten. Ik heb genoten van de mooie kleuren groen van de bomen.
Dit is een van mijn favoriete plekken.
Toen we terug liepen kwamen we nog drie koeien tegen, die ons luid loeiend begroetten.

Ter afsluiting hebben we een heerlijk kopje koffie genomen bij La Place in Maarsbergen.
We hebben genoten van deze mooie nazomerdag.

Mijn vrouw heeft nog twee foto's van de schaapskudde gemaakt.
Schaapskudde Leersumse veld

maandag 8 september 2014

PC4T with 5 watts on 14 MHz with WSPR

Here is a WSPR Propagation Analysis of spots of Paul PC4T on 14 MHz.
The lower the Calculated lowest possible power, the better the propagation.
Nearly all spots over 1100 to 2200 kilometer could have been made with 20 milliwatts.

Update 2014-09-10
I made an extra analysis of the spots in the red fields.
The spots were made from 19:12 till 19:40 UTC
The lower the Calculated Lowest Possible Power, the better is the propagation.

LA9JO at 2000 km
The signal strength increases with 6 dB (in power 4x as strong) from 19:12 till 19:40 utc.

The last spot is 14 dB weaker than the first.

The last spot is slightly stornger than the other two.

donderdag 14 augustus 2014

Schematic and building info of the 6 watt Power Attenuator

PA1B 40 dB Power Attenuator
PA1B Fast and accurate 40 dB Power Attenuator for QSO's

This Power attenuator is  fast in CW QSO's, because
7 dB and 3 dB can be switched instandly..
The attenuator is also very accurate.

Power Attenuator
All attenuator sections are designed for an maximum input power of 6 watts. The continuous power is 1.5 watt.
The power resistors, with a lower ohmic value, dissipate most of the power and an other resistor is added in parallel, to arrive accurately on the wanted ohmic value. 
The power attenuator sections of 20 dB and 10 dB are build with 7 resistors, since they must dissipate much more power than the other sections.
The large resistors are resistors of 2 watts. The resistors with 2 stars (**) are resistor of 1/2 watt and the resistors with 1 star (*) are resistors of 1/4 watt.
I built my attenuator with metal film resistors of 2 watts, 600 mW (*) and 400 mW (*)

Asymmetrical attenuator
To reduce the number of resistors, I chose for asymmetrical sections in the attenuator. 
Input and output can not be exchanged.

PA1B Fast and accurate 40 dB Power Attenuator for QSO's.
Power 6 watts built with resistors of 2 watts, 1/2 watt and 1/4 watt
Click to enlarge

The switches on the front.      20 - 10 - 7 - 3 dB        
Reversed order
The schematic goes from left to right.
Please notice that the layout on the switches, inside the box goes from right to left.
So you will find the the resistors of 150 ohm and 330 omh to the right.
Notice the reverse order with respect to the schematic
R2 and R5 are also placed

Naar Blijdorp met Eneco

Als trouwe klant van Eneco, kregen een aanbieding om met Eneco gratis naar Blijdorp (Rotterdam Zoo) te kunnen gaan.
Dus besloten we al snel om met onze kleindochters te gaan.

We hebben genoten.

Apen met roze konten leidde tot grote hilariteit.

Neushoorn, Giraffen en een opa's lieveling, de otter

  Eneco, bedankt voor het fijne bezoek.

dinsdag 12 augustus 2014

PA1B 20 - 10 - 7 - 3 dB power attenuator measured

We measured the new built 6 watt PA1B  Power Attenuator, in the shack of Mischa PA1OKZ.
The attenuator is built with metal film resistors of 2 watts, 600 mW and 400 mW, from the E12-series.
I was curious how well the metal film would do HF.       Click for schematic

* The 20 - 10 - 7 - 3 dB  sections are very accurate
* The 20 and 10 dB  sections show an accuracy of 0.1 dB to 0.2 dB at 30 MHz
* When all sections are switched OFF, the attenautor has a attenuation of
    0.13 dB at 1 MHz  to 0.61 dB at 30 MHz.
    This "extra" attenuation is frequency dependent.

Relative attenuation
The purpose of an attenuator is to attenuate the signal with the value 
of the sections, that are switched "ON".
In this table the attenuation with all section switched OFF is 0 dB.
The table shows the "extra" attenuation of this section, when a section is switched "ON ".
Relative attenuation of the PA1B  20 - 10 - 7 - 3 dB power attenuator    
At 10 MHz all sections are very accurate.
The 10 dB and 20 dB sections are more frequency dependent.
The section of 3 dB is the most accurate section. The section of 7 dB has an accuracy of 0.1 dB.
The section of 10 dB and 20 dB show an accuracy of 0.15 dB at 30 MHz.

I am very content with these values, considered that the resistors are resistors of 5% from
the E12-series. The measured values of all resistors in this attenuator, show that the accuracy of the resistors is about 2 %.

Absolute attenuation
This "extra" attenuation is caused by the fact, that the circuit formed by switches is not 50 ohm.
The value of 0.13 to 0.61 dB is typical for the switches that are used and the distance between the switches.
We measured about the same values in another attenuator with two section of 20 dB and one of 10 dB, that is built in the same way.
Absolute attenuation of the PA1B  20 - 10 - 7 - 3 dB power attenuator     
Inside of the box of the attenuator with simplified schematic

woensdag 30 juli 2014

Building a 6 watt power attenuator

I am building an attenuator with metal film resistor of 2 watts, 600 mW and 400 mW.
Sorting out the resistors
Click to enlarge
The store had no resistors of 1 watt, so I bought the power resistors
of 2 W and made a redesign of the attenuator.
All the resistors are metal film resistors.

The attenuator is designed to for a maximum power of  6 watts.

To the right you see the blue  box with the resistors that are needed.
The 3 dB and 7 dB sections both consist of 6 resistors each.
The 10 dB and 20 dB sections dissipate more power.
They consist of 7 resistors each.

     Outside of the box with the 20 dB section to the left.                         Inside of the box. 20 dB section to the right.                     Switches set to 17 dB                                                                             Switched mounted               
Next step soldering the resistors. 

zondag 13 juli 2014

Accurate and fast 5 watt attenuator for QSO's

Please visit the PA1B QRPp page for more info on Power Attenuators.

Fast in QSO's
A simple way to reduce the power of your QRP set to milliwatt level, without modifying the set, is the use of attenuators. The combination of 20 dB, 10 dB, 7 dB and 3 dB is fast to switch, when you want to increase your power in QSO's. In one move, one attenuator section is switched OFF and an other is switched ON, to increase the power with a step of 3 db or 4 dB.

PA1B Fast and Accuarate 40 dB Power Attenuator for QSO's
PA1B Fast and accurate 40 dB Power Attenuator for QSO's
Asymmetrical attenuator
I choose to design this attenuator asymmetrically, to reduce the number of resistors.
Please notice that the resistor on the input of each attenuator section, R1, R4 and R7, consist of 5, 4,and 3 resistors.

All attenuator sections are designed for an maximum input power of 5 watts.
This is a continuous power of 1.25 watt.
The attenuator sections consist each of 3 compound resistors, which each are formed by a number of resistors in parallel. These resistors are a power resistor of 1 watts and a some resistor of a modest power (1/4 watt). The resistors with a star * can be 1/4 watt.
Or you can chose  1 watt resistors for all resistors.
The power resistors, with a lower ohmic value, dissipate most of the power and an other resistor is added in parallel, to arrive accurately on the wanted ohmic value. The power attenuator sections of 20 dB and 10 dB are build with 9 resistors, since they must dissipate much more power than the other sections.

With two or more resistors from the E12-series in parallel,
you can accurately make any value you want.
The resistor value of the combination is most of the time within 1% of the theoretical value.
This is why an accurate attenuator section, always consists of 6 resistors or more.

Simple layout
The choice of placing resistors in parallel, leads to a very simple layout of the attenuator sections.
There's NO need for a PCB. hi.

Table for the PA1B Fast and accurate  40 dB  Power Attenuator
Click here for

PA1B Fast and accurate 40 dB Power Attenuators for QSO's

for a symmetrical attenuator built with resistors of 2 watts

donderdag 10 juli 2014

First place in the YO DX HF contest 2013 for CS8/PA1B

Today I received a beautiful Award of the YO DX HF contest.
Last year I partcipated while on holiday on the beautiful island of Saõ Miguel on the Azores.

During the contest I used an end fed wire on the roof of the hotel.
In the contest I used my FT-817 with 2.5 watts or less and a homemade light weight keyer.

The envelop from Romenia arrived in the rain.
When my wife entered the room with the wet envelop, she said:
"I hope all is OK".
I immediately recognized the envelop of the YO DX contest.
Despite the rain the Award is in good condition, because it is plasticized.

My thank goes to Ovidiu YO2DFA, the contest manager of the
YO DX HF contest.
CS8/PA1B   First place in YO DX HF - Azores - Single OP - 14 MHz - Mix 

zondag 22 juni 2014

Two eQSLs over more than 2000 Miles

RF9T  2080 miles and 800 mW gives 2600 MPW
In the batch of eQSL cards,
I received a card from from RF9T.

With a distance of more than 2000 Miles to UA9, its easy to make a more than 1000 Miles/Watt QSO, when I reduce the power below 1 Watt.

The eQSL card of RK9UE was received earlier and was made with even less power. hi

RK9UE  3126 miles and 360 mW gives 8684 MPW
1000 Miles per Watt is not as difficult as it seems.
When you hear a station over a distance of  500 miles (800 km), just reduce to 500 milliwatts.

dinsdag 3 juni 2014

PACC 2014

The PACC is the annual contest from the Netherlands.

In other contests I always work with search and pounce with very low power, but in the PACC
I operate by giving CQ myself. Most QSO's were made with the highest power of my FT-817.
Last year the top of my inverted vee broken during a storm. I repaired the antenna temporarily.
One wire lays on the roof. Still I managed to make more than 130 QSO's.

I notice a difference with this antenna but the differences  due to changes in propagation, are larger.
I made more than 130 QSO's with 29 different DXCC's, with less than 5 watts.

Because we had visitors I could not start at 12:00 utc.
I did not wake up early on Sunday.

 De top van de Inverted V hangt slechts een paar meter boven het dak, nadat ik hem weer
provisorisch opgehangen heb, na een storm verleden jaar. Een draad ligt gedeeltelijk op het dak.
Tot mijn verbazing maak ik nog vele QSO's met QRP en zelfs met QRPp.
Dit wijst er op, dat de propagatie belangrijker is dan de antenne.
Ik maakte 138 QSO's met 29 DXCC landen met 500 mW tot 5 W in de contest.
Bedankt voor de activiteit in de PACC.

As a milliwatt and QRPp enthusiast very much like the "DX contests" in which every one works every one.

OP1A  in the PACC  2011

zaterdag 24 mei 2014


Here are some eQSLs' from the last batch.
The QSO's are all made QRPpp and while using the Lowest Possible Power.
QRPpp is the (not official) term, that I use for a power of less than 100 milliwatts.
Also known as two digit milliwatting.

Making QSO's with very  low power is not that difficult.
It´s all a matter of propagation.
The changes in propagation can be hugh.
So when the S-meter goes 20 dB up, the power can be reduced with 20 dB.

Look for a CQ of a station with an earsplitting S++ signal.
Answer with low power, with the excellent timing that you always use.
Don´t suspect anything, but be prepared after you give your call.
Most of the time, other stations are answered.
But than suddenly, the frequency is clear and you will be heard.
It´s possible that you are surprised, that you hear your call, being send immediately correct.
And before you know it, you also get an exchange. What was that? What number did he gave? hi.

9H1XT    1205 Miles   3.6 mW   334841 Miles per Watt

IV3ZXQ   550 Miles   22 mW   25002 MPW

SM5QU   740 Miles   36 mW   20549 Miles per Watt

SV1ENG   1318 Miles   98 mW   13453 Miles per Watt

S56M   588 Miles   80 mW   7349 Miles per Watt

OE2008S   445 Miles   98 mW   4698 Miles per Watt
See me smile, from ear to ear, after such a QSO.