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 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

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: https://www.youtube.com/watch?v=rvpxyoacrec

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