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Bert PA1B

Bert (PA1B) Lees in het Nederlands My name is Bert and my call is PA1B.

I made this PA1B QRPp page, to show the possibilities of QRP and QRPp.
And to show, how I operate with the Lowest Possible Power in CW contest QSO's.
I enjoyed writing these very informative pages, especialy the page on attenuators and the unique Power Attenuator Calculator.
I developed the Power Attenuator Calculator to enable you, to effortlessly design your own Power Attenuator.

My interests as a HAM are: contesting in CW, with QRP or QRPp on HF and 1000 Miles per Watt.
And further the use of homebrew Rig's, homebrew antennas and homebrew tuners and homebrew keyers.

J47 Straight key In most QSO's (radio connections) I use CW (Morse code)CW
Morse code is still in use by radio amateurs, because long distances can easily be bridged by the use of Morse code.
In CW QSO's I use a Bencher and a Morse machine.
In the picture you can see me operating my homebrew light weight holiday squeeze keyer.

I often participate in radio contests, which give a very good opportunity to make interesting QSOs.
In radio contests, many stations from many different countries and special radio stations are active.

FT-817 and attenuators Most of the time I use my Yaesu FT-817, with a CW filter with a bandwidth of 500 Hz.
I always use QRP. For CW, this is a power of 5 watts, or less.
But most of the time I use 500 mW or 1 Watt.
I use attenuators, built with resistors from the E12-series, to make QSO's with my FT-817 with less than 500 mW.
My antenna is an Inverted Vee, that I use since I started as a HAM.

Confirmed DXCC's In CW contests QSO's I often reduce to the Lowest Possible Power from QSO to QSO.
When the S-meter goes up, my power goes down.

Please place a bookmark to this page to come back later, because there is more interesting infomation, than you can read in just one visit. hi.
If you like this PA1B QRPp page, please feel free to add a link to this page on your web site and your Blog.


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

Fast and accurate 40 dB Power Attenuator for 6 watts with metal film resistors of 2 watts,
Table for 20-10-7-3 dB attenuator 40 dB Power Attenuator with 6 watt Input 40 dB Power Attenuator with 6 watt Input

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.

To reduce the number of resistors, I chose to use good available metal film resistors of 2 watts.
All attenuator sections are designed for an continuous input power of 6 watts. This is 12 watts in CW.

Read further, on the interesting Attenuator page, about a fast and accurate   40 dB Power Attenuator   for 6 watts,
so you can reduce the power of your 5 watt QRP transceiver in steps of 3 dB.


PA1B's QRPp Blog

PA1B's QRPp Blog In addtion to this PA1B QRPp page, which I can not up date myself directly,
I started the PA1B's QRPp Blog, which also gives room for comments.
In this Blog I give current information. I can up date the Blog myself, at any moment.
At the top of the Blog you can find TABs on interesting, "timeless" topics
and some interesting info copied from this PA1B QRPp page.


Confirmed QSO's per DXCC and power category

Confirmed DXCC's I am proud to present the results of the confirmed DXCC countries, especially those with QRPpp.
Are you curious, what is possible with very low power, please click on this
spectaculair overview of all confirmed QSO's per DXCC country per power category.


The use of attenuators

FT-817 with attenuators of 20 dB and 10 dB When the propagation is very good to extremely good and the received signals are S9 plus 10dB or more,
QSO's can be made with 100 mW or 50mW. Using very low power is great fun.
When the S-meter goes up, my power goes down
I use accurate attenuators, built with resistors, from the E12-series, to make QSO's with less than 500 mW.

Please read more about, how to build and use very accurate 50 ohm attenuators on the interesting Attenuator page.


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

Fast and accurate 40 dB Power Attenuator for 5 watts with carbon resistors of 1 watt,
40 dB Power Attenuator with 5 watts Input 40 dB Power Attenuator with 5 watts Input
A power attenuator is an attenuator for an input power of several watts.
The power attenuators on this site are all built with several resistors in parallel.
By placing the resistors in parallel, the power is distributed over the resistors.
The higher the input power, the more resistors are needed.
The attenuators are and designed with resistors of a modest power, from the E12-series.

Please notice that this attenuator is asymmetrical.
Input and output can NOT be reversed.

Read further, on the interesting Attenuator page, to build a fast and accurate   40 dB Power Attenuator   for 5 watts,
so you can reduce the power of your 5 watt QRP transceiver in steps of 3 dB.


Power Attenuator Calculator

Power Attenuator Calculator All attenuators on this page are designed with the Power Attenuator Calculator.

With the power attenuator calculator you can design your own power attenuator with widely available induction free resistors from the E12-series.
Design your own power attenuator with widely available induction free resistors from the E12-series.
The use of this unique Power Attenuator Calculator, eliminates the need of high power resistors, to build a power attenuator.
You can design your own power attenuator for an any input power you want, with this unique Calculator.

Go to the unique and excellent Power Attenuator Calculator (in Excel), which calculates the number of resistors an their values.

In 2014 I extended the Calculator to 1 dB, 2 dB, 3 dB, 7 dB, 10 dB and 20 dB, to develop fast and accurate power attenuators.


Power Attenuators with carbon resistors from the E12-series for the FT-817 - Published in SPRAT 152

Please note the corrected layout from the article in Sprat to the right
The arrows show the right connections of R2 and R5.

Click to enlarge

            Read the interesting article published in SPRAT 152.
1.5 W Continuous input power with resistors of 1/2 W.


Lowest Possible Power

In many contest QSO's I try to use the Lowest Possible Power in each QSO. In most QSO's I answer a CQ instead of calling CQ myself. First I adjust to a power that is probably just high enough to make the QSO. I answer by giving my call just once or twice. Then I listen. When the station is still calling CQ after my call, my signal is not heard. Only when I notice that my signal is not heard, I increase the power and try again. If the station answers an other station, I wait patiently.
The frequency must be absolutely clear for my signal to be heard. With many other callers in a contest, this can be frustrating. But many times suddenly when I am the only station calling, the station repeats my call, immediately correct and gives his report. Most of the time I receive 599. (hi) After sending my exchange, I can log the QSO. By operating in such a way, I have great fun with very low power and at the same time I develope my operating skills.
Sometimes I start with a power that is probably to low, because in a contest I can not make a second QSO with the same contest station, with a lower power.

In my log I note my power in every QSO. In my log I also have special columns for miles and miles per watt
I always use QRP, but I never use the tag /QRP in a contest QSO. I rather use the time to repeat my call, than to give /QRP.


Lowest Possible Power

Using the
Lowest Possible Power
is QRO -ing
with low power
or very low power.



How is it possible?

500 mW is 4-Spoits down from 100 W
Table for FT-817 and the attenuator A CW signal with a signal strength of S9 is very strong. But a signal with S5 or even lower can be received easily.
If a station, that is transmitting with 100 W, is received with a signal strenght of S9, then my 500 mW signal will be received with 559.
This is 4 S-point down. The signal will not be very strong, but the readable will be good.

When the propagation is good to extremely good, the signal of the 100 W station will be S9 + 10 dB, so I can reduce my power to 50 mW, using an attenuator of 10 dB and still be received with 559. hi
When I increase my power, when my signal is not heard, I usualy "double" the power. Then I try again.
This is a step of 3 dB. This is the optimal step to increase the power.

FT-817 with attenuators of 10 dB and 20 dB I noticed in many QSO's "on the edge", that when I was heard, but my call was not copied even after repeating 10 times, that my call was immediately copied correct with the doubled power.
A step is 1 dB is too small and a step of 10 dB is too large.
The steps of 3 dB or 4 dB are an excellent choice of the designers of the Yeasu FT-817

When I use an attenuator, I transmit, but also listen trough the attenuator.

Depending upon the signal strength of the received signal, I use QRP, QRPp or QRPpp.
QRP means using a power of 5 watts or less in CW (or 10 watts in phone).
QRPp is less then 1 watt, also called milliwatting.
QRPpp is the (not official) term I use for a power less than 100 mW. This is also known as two digit milliwatting".


QRPp in an aftenoon with a 10 dB attenuator

10 dB Attenuator You can also work with the Lowest Possible Power.
Build your self a simple, easy to build, 10 dB attenuator, with good available resistors, to go QRPp in one afternoon.
Here are 4 simple 10 dB attenuators, each for a different input power, to make a Quick Start in to QRPp.


WSPR with attenuators

Attenuator 20 dB Input 1 watt How about WSPR with 50 mW, to experience WSPR, just how it is ment to be QRSS and QRPp
Use your QRP-set, with all its features to use WSPR with 50 mW or with 10 mW.
Read further about: 20 dB Attenuators for WSPR, which are designed for a continuous input power of 5 watts or for 1 watt.

But also read: The use of attenuators for QSO's with very low power.


Some of my homebrew equipment

In special contests as the OQRP contest, I use my homebrew CW transceivers HM7, and HDC14
Building and operating with homebrew equipment is great fun. Click on a picture to select my homemade equipment.




Inverted Vee

Holiday transmatch



Inverted Vee

Holiday transmatch
Read about the Award from CT


1 milliwatt QSOs

QSL-Cards of QSOs with only 1 mW Over the years I made many QSOs with very low power.
But I only made a few QSOs with 1 milliwatt.
The QSO's with RT6A over more than 1500 miles and with RU1A over more than 1000 miles,
are both good for more than ONE MILLION miles per watt.
QSL-Cards of QSOs with only 1 mW

Click on the cards to read the interesting stories of of the four 1 milliwatt QSO's.a


NAQCC 1000 Miles per Watt Award

NAQCC 1000 Miles per Watt Award For years I am a member of the NAQCC. (#2038)
The NAQCC club activities are dedicated to QRP/QRPp operation, using CW.
When I visited the Award page in August 2011, I got excited by the extensive Award program for QRP and QRPp.
Over the years I have made hundreds of confirmed QSO's with more than 1000 Miles per Watt,
but untill now, I had not yet applied for an award.
So I decided to apply for the 1000 MPW Award.
I choose to apply for the QSO with the highes Miles per Watt.
This QSO with RT6A was made in the Russian DX contest in August 2007.
A few days later, I recieved the beautifull NAQCC Simple wire antena 1000 Milies per Watt Award,
sent by e-mail, from the Award manager, Rick AA4W.

Check out the interesting Awards of the NAQCC.

Take a look at the winners of the Awards.
Click on the Award to read the details of the 0.85 mW QSO with RT6A.


1000 MPW QSOs

Minimal distance and Maximum power Using very low power, I make many QSOs with more than 1000 Miles per Watt
After many QSOs with 50 mW or less, I realised that I had breached the 1000 MPW boundary many times.
From The Netherlands to Germany with 50 mW or to France with 100 mW is also good for more than 1000 MPW
But dont think that you need very low power for a more than 1000 miles per watt QSO.
A QSO with only 1 watt from The Netherlands to Moscow over 1300 miles will do.
Or even a QSO to Canada or the USA with only 2.6 watts from the FT-817 does the trick.

Just reduce you power below 5 watts, to make more than 1000 Miles per Watt QSO's easily.


How to calculate the distance and Miles per Watt yourself

Find your QTH locator by F6FVY N9SSA Distance and MPW Calculator First determine your QTH locator with the excellent: Find your QTH locator by F6FVY Laurent Haas.
Zoom in on your city and then click on your street to find your QTH locator.

Then calculate the distance with the fantastic "Miles per Watt calculator" by N9SSA.
Copy the two QTH locators and paste them, one by one, into the fields Grid-Square.
Fill in the power in the field Watts. (give 0.05 for 50mW)
Press the button Calculate Distance and be surprised. (hi)

My QTH locator is JO22na


My 1000 MPW QSL card

1000 Miles per Watt QSL-card 1000 Miles per Watt QSL-card For more than tree years, I send a special
more than 1000 Miles per Watt QSL card,
for every more than 1000 Miles per Watt QSO that I make.

Click on the card to see the backside of the card, with all the interesting info for 1000 Miles per Watt.



1000 Miles per Watt award If the calculation gives more than 1000 Miles per Watt you can apply for the 1000 Miles per Watt Award that is issued by QRPARCI.

This Award is issued to amateurs that RECEIVED or MADE a QSO with a QRP station that exceeds 1000 miles per watt, calculated from the power of the QRP station. You can apply, even when you are using QRO or as SWL.

Learn here more about the rules for the Awards.


Confirmed countries in QRPp

Look at my PA1B QRPp mW DXCC country list in PDF format. Over the last years I have received many QSL-cards for QSOs with very low power, to many DXCC countries.

Feel free to have a look in the PA1B QRPp mW DXCC country list, which can be viewed in Look at my PA1B QRPp mW DXCC country list in PDF format. format.

Notice that this list is only for DXCC Countries confirmed in QRPp.


Changing conditions

QSO's over the years Over the years I noticed that the conditions are declining.
I need 3 dB (2x) or 6 dB (4x) more power for the same run of contest QSOs than a few years before.
But the good news is that milliwatting and making QSOs with more than 1000 Miles per Watt is still possible in EVERY contest.

Check out here the influence of the conditions on the Lowest Possible Power, in this spectaculair overview of confirmed QSO's per year.


How I started

When I started as a HAM on HF, I built my first transceiver myself. I had great fun with this homebrew CW QRPp transceiver the HM7.
The rig comes from "Solid State Design for the radio amateur" page 214...218.
In the 10 years that I used this CW transceiver, I worked many European countries on 7 MHz with a power of only 500 milliwatts in many normal QSO's and many contest QSO's.
Homebrew, QRP and CW (morse code) is a fabulous combination.

After I had worked with this transceiver for a half year, I met Piero I5FPJ from Florence.
After I mentioned that I worked with 1 watt, he reduced the power.
I noticed, that when Piero went from 100 watts to 3 watts (-15 dB), the signal was less loud, but the readability of the signal was still good. Only the background noise was stronger.
When Piero went from 3 watts, via 2 watts to 1 watt (-5 dB), I noticed that the signal strength only reduced a little bit.
And when we were both running 1 watt, the signals were still good, with only more noise in the background.
With this knowlegde, I reduced the power of the HM7 from 1 watt to 500 milliwatts, a few months later.

In 2001 I bought a Yeasu FT-817. The power is adjustable from 500 mW, 1 W, 2.5 W to 5 W. Most of the time I use to the lowest power and increase the power only when necessary.
As antenna I use an inverted V with a 300 ohm ribbon as feeder. The antenna match-unit is a homebrew symmetrical tuner.

To reduce my power further when possible, I built an attenuator of 10 dB and 20 dB.
I noticed that for a QSO with 500 mW the received signal must be 599 or stronger.
When signals are S9 plus 10dB I can reduce my power to 50 milliwatts using the rig with an output of 500 mW and an attenuator of 10 dB. (10 dB reduces the power from 500 mW to 50 mW)
Being familiar with 500 mW, the step to QRPpp is easy. QRPpp is a (not official) term that I use for a power lower than 100 milliwatts.


Grijze onzichtbare kop

  Send a personal e-mail to Bert (PA1B).  
  Send a personal e-mail to Bert  
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