Minimalist QRP
Book
by
IZ3AYQ
V5.3

Pixie transceiver, 7023 kHz, 900 mW in a modem box.
1

This manual is for free distribution and for amateur radio use; any commercial
use is prohibited.
A big thanks to Oleg Borodin, RX3G, for the RTX projects he provided me, andfor the continuous stimulus in QRP activities.

Why this book?
This book aims to collect and share knowledge related to the art of QRP. There aremany schemes and projects available on the web, but after some time someschemes disappear if the sites are no longer maintained.
It is therefore a question of collecting this knowledge and trying to give as complete
an overview as possible of this branch of radiantism.
Last but not least, the projects are minimalist, not because you can't do better, but
because:- An amateur radio operator should use the minimum necessary power tomake a QSO;
- Because they are affordable designs, usually feasible without special
electronic equipment;- Because the great satisfaction lies in building and using something of
one's own, rather than just using super equipment, even very beautiful ones, butwhich can only place us as users of a technology we master very little;- Because they are an important stimulus to learn, and you learn from thebasics.
- Because they are a base that you can modify at will, introducing endless
improvements.
- Because with a simple design I can find the components more easily.
- Last but not least because making links in QRP, QRPp or QRPx is achallenge and a lot of fun together.
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3

I invite those who are passionate about downloading the diagramsand documentation available on the Internet; in fact, if you see andtry to search, after a few years some sites are no longer maintained
and online, so even the diagrams are lost over time. So it's not abad thing to download and keep them, not throwing away thatheritage of tests, trials and experience that other radio amateurs
have done before us. I think that these circuits are a story that wehave to preserve, because they represent a heritage and a stimulus
to do and understand more.

4Summary
Minimalist RTX QRP, QRPp and QRPx ................................................................................ 8
What we can do with low power ............................................................................................ 9
Transceivers ....................................................................................................................... 10
MICRO80 ........................................................................................................................ 10
The Micro 80 D ................................................................................................................ 12
PIXIE, PIXIE2 .................................................................................................................. 14
Another Pixie for 80 m: .................................................................................................... 15
The Chinese Pixie ........................................................................................................... 18
Another Chinese Pixie ..................................................................................................... 19
40 m FT8 by BD6CR ....................................................................................................... 19
KNIGHT SMITE: .............................................................................................................. 21
TINY TORNADO ............................................................................................................. 22
1 WATTER ...................................................................................................................... 25
80 m CW Transceiver XBM80-2 ...................................................................................... 25
FOXX-2 ........................................................................................................................... 26
THE TENNER & THE PIPIT ............................................................................................ 27
THE 49’ER ...................................................................................................................... 29
Uu80b Transceiver by G3XBM ....................................................................................... 30
Curumin by PY2OHH and modification by ON4XMJ ........................................................ 30
4SQRP Cricket 80a ......................................................................................................... 31
The 10 m Lesser Chirpy .................................................................................................. 32
FET Transceiver 80 m by G3XBM ................................................................................... 33
Wispy-10 WSPR RTX ...................................................................................................... 34
VK2ZAY version of XBM80-2 .......................................................................................... 35
1944 one tube TRX ......................................................................................................... 35
One tube amateur station, by W9SCH ............................................................................. 36
The Bell Ringer, 20 m RTX by AA1TJ.............................................................................. 37
The MAS-Transceiver by DK1HE .................................................................................... 38
The Pititico ...................................................................................................................... 38
The JU-6 7-14 MHz Transceiver by G3DOP .................................................................... 39
RTX Polevik by RA3AAE ................................................................................................. 40
5

RTX Polevik 20 + 40 by R2DNN ...................................................................................... 40
TRX 40 m by R2DNN ...................................................................................................... 41
MAS 2013 ....................................................................................................................... 42
One transistor transceiver by KV6Z ................................................................................. 42
HA4OO Transceiver ........................................................................................................ 43
DSB microtransceiver ...................................................................................................... 43
DSB microtransceiver 21 MHz ......................................................................................... 44
The Gnat 40 RTX ............................................................................................................ 45
Polish NE612 DSB Transceiver ....................................................................................... 46
Mosquito TRX.................................................................................................................. 48
Transmitters ........................................................................................................................ 49
THE OXO: ....................................................................................................................... 49
30 m QRPp TX by DL6ZB .............................................................................................. 50
THE NOGAnaut............................................................................................................... 51
VA3IUL TX ...................................................................................................................... 51
LU1AR RTX 10W 80m .................................................................................................... 52
The Michigan Mighty Mite ................................................................................................ 53
The Vanguard.................................................................................................................. 54
One BJT Transmitter by K4TWJ ...................................................................................... 55
One Watt CW Transmitter ............................................................................................... 56
Ten Minute Transmitter ................................................................................................... 56
Four States QRP ............................................................................................................. 57
One BJT Transmitter 700 mW ......................................................................................... 57
TX 5 MHz ........................................................................................................................ 58
Little Joe .......................................................................................................................... 59
TX and power amplifier.................................................................................................... 60
The Walnut TX by PA3DMI.............................................................................................. 60
Valvular TX ...................................................................................................................... 61
Emergency transmitter – A 8 components 10W 40m/30m TX by SV3ORA...................... 62
Russian transmitter “Paloma” .......................................................................................... 63
20 m 1 tube QRP Transceiver by UY1IF.......................................................................... 64
Receivers ............................................................................................................................ 65
MTRX-20 ......................................................................................................................... 65
MRX-30 ........................................................................................................................... 66
MRX-40 ........................................................................................................................... 67
1,5 V DC Receiver by DL6ZB .......................................................................................... 68
6

1 CHIP RX 80 m by G0FGI............................................................................................. 68
A REGEN RECEIVER: .................................................................................................... 69
Russian DC RX ............................................................................................................... 69
Russian DC RX 2 ............................................................................................................ 70
RX 69 .............................................................................................................................. 70
Tiny SDR by LY1GP ........................................................................................................ 71
Sudden Storm Receiver .................................................................................................. 72
The “Micro-Scope” - very simple 20 m D.C. RX for portable operation ............................ 73
Utilities ................................................................................................................................ 75
Il Super VXO ................................................................................................................... 75
Audio Amplifier ................................................................................................................ 75
S-meter circuit ................................................................................................................. 77

7

Minimalist RTX QRP, QRPp and QRPx
Meaning of the terms:
QRP: power used less than or equal to 5 watt
QRPp: power used less than or equal to 1 watt
QRPx: power used less than or equal to 100 milliwatt
QRPu: power used less than or equal to 10 mW
Microwatting: power used less than or equal to mW
If it is possible to make connections in QRP (power of 5 watts or less) it is also possible to
make them with 1 watt or less; this is the characteristic of QRPp. On the web you can find a
lot of connection experiences made with 0.5 - 1 watt, often with self-built RTX. Very often
simple wired antennas are used, and of course telegraphy (but there are also digital modes,
which use communication protocols that allow transmission over thousands of kilometerswith a few milliwatts). Of course, it is a great satisfaction to connect, for example, a station
with a power of 700 watts and 9 element yagi antenna, with just 2 watts and a wired
antenna! These connections are possible if the correspondent is patient, and especially if hedoes not require signals of the 9++ type.
Let's see why connections are possible even with little power, with a table expressing thesignal level received from the correspondent starting from the transmitted power (~ means
about, as the numbers have been rounded).
POWER
Received
signalReceived
signalReceived
signalReceived
signalReceived
signal

100 WATT
95 WATT
7

2 WATT
6

1 WATT
5,50,1 WATT
4

8

6

5

4,5

3

7

5

4

3,5

2

6

4

3

2,5

1

5

3

2

1,5

0

The table means, for example, that if in a connection with 100 watts I make myself heard
with signal 8, lowering the power to 1 watt, I can make myself heard with signal about 4.5, allother conditions being equal.
It is therefore evident that there are, band noise permitting, many possibilities to makeconnections both in QRP and with lower power.

8Moreover, using telegraphy, I have many more possibilities to make myself heard than withthe voice (USB and LSB). Not to mention digital protocols such as FT8, JT65 and others thatallow to operate with even lower power.

What we can do with low power
This is an example of stations using less than 100 mW or less than 10mW or less than 1
mW. Hundreds of entities DXCC !!!! Hundres of grids!!! So, it is really possible, and even 5
watt seem to be too much !!! In the last table you can see RX3G with 13 entities DXCC andOM6TC with 1 entity with a power of about half milliwatt.

9

Transceivers
MICRO80
RTX by RV3GM, Oleg Borodin: RTX for 80 meters, single quartz frequency, only 4transistors, 300 mW power, direct conversion receiver. Also possible for 40 and 30 meters,always with quartz on QRP frequency. Simple and minimalist. I report first this transceiver,
because it is the progenitor of a long series.

Here is another scheme with different transistors, always for the 80 meters:

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11

The Micro 80 D

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PIXIE, PIXIE2
RTX Pixie: we find many versions, for 80, 40, 30, 20, 15, 10 meters. It is a simple evolutionof the Micro80. Power about 1 watt or less, single quartz frequency, direct conversion; insome schemes we use a VXO, which gives some kHz more bandwidth; as audio amplifier
we use the LM386; some schemes have the automatic RIT for +/-700 Hz reception.
It is a simple circuit, subject to many improvements and modifications. Many OM have triedand many have written on Pixie: KA8MAV, KX7L, F6BQU, AL7FS, KL7ILX, WE6W, W1FB,
KL7AQL, WA6BOY, JA9MAT and many others.
There are several QRP clubs that have published documentation on this small transceiver: I
remember the G-QRP that published "The Pixie File" a pdf with a collection of schematics,
easily available on the internet. Generally these RTXs suffer from strong input signals,
especially broadcasting, because they don't have narrow front end filters, but everyone canwork on this! Here is a series of diagrams.

14

Another Pixie for 80 m:

Pixie for 80 m by SP5DDJ; with TX offset, with super VXO and Buffer.

15

Pixie by KX7L

16

Pixie by KE3IJ: the “RixPix”

17

The Chinese Pixie
The Chinese version of Pixie, which can be found in Ebay: this version of Pixie (similarly to
Rock Mite, which was born first) has a quartz in series at the input of the receiver, always on
the frequency of 7023 kHz, identical to the receiving frequency, in order to reduce thebandwidth and therefore the noise and interference, as much as possible (it is the quartz infront of the NE602 integrated). The NE602 mixer and oscillator allows a gain of about 18 dB;
the same integrated is used in many similar schemes and in particular in RockMite.

18

Another Chinese Pixie

40 m FT8 by BD6CR

19

Below is the Pixie of W1FB, equipped with an audio filter with 741 operational circuit (andRX – TX shift circuit management).

20

KNIGHT SMITE:
It is an SMT version of the Pixie2, produced for 80 meters. The kit is "sold out", but diagrams
and PCB layouts are available on the site. It has features such as: VXO, direct conversion,
less than watt output power, using the "very powerful" 2N2222 power amplifier.

21

TINY TORNADODeveloped by K8MAV, in the wake of Pixie2, it is very similar, with some improvements (e.g.
it features manual frequency switching between TX and RX, or rather switches between twovery close frequencies). It presents calculations for low pass output filters for 80, 40, 30, 20,
10 meters. Direct conversion scheme, about 1 watt of power, but generally less, no front end
bandpass filters.

22

ROCK MITE
RTX designed by K1SWL, is a single quartz RTX, with two very close frequencies (RX andTX) that can be exchanged, 0.5 watts of power, sidetone, automatic frequency shift intransmission, built-in and adjustable keyer, front end filter with a quartz of the same
frequency as that of reception and transmission, generally for 80, 40, 30 and 20 m.
Hundreds of connections have been made with 0.5 watts: of 1000, 2000, 3000 km and evenmore (see N5ESE, N5FC and many others). Very few components and a deadly
optimization to obtain in a small card of 5 cm x 6 cm all these features ! One of the remaining
manufacturers is Kanga Products at this link: RockMite
Warning because other kits available on the web do not have the keyer and quartz filter
input.
Here are some Rock Mite schemes:

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24

1 WATTER
The "1 Watter" is a QRPp kit with VXO available for the 160, 80, 40, 30, 20, 17 and 10 meterbands. The name comes from the output power, 1 watt, in CW. It costs $47 and can befound at: http://kitsandparts.com .
It's a monoband, double conversion kit. The tunable frequency band is about 5-7 kHz for
160, 80, 20, 15 meters; about 18-19 kHz for 40, 30, 17 meters and about 9 kHz for 10
meters. For selectivity three-stage quartz filter dipsone (feature not present in many otherminimalist circuits), and has integrated keyer, sidetone and shift in automatic listening. Also
includes skipping SMT components. The features are absolutely good for the cost.

80 m CW Transceiver XBM80-2

25

FOXX-2
Product kit in 80, 60, 40, 30 and 20 meters version. It is single frequency, with VXO crystal
oscillator, minimal, direct conversion; it has about 1 watt output power, in CW. It has
sidetone and listening with automatic shift in RX; listening through the classic LM386, as in
Pixie. The link where to go for the kit is the following:
http://www.kanga-products.co.uk/index.php
The diagram is as follows:
Translated with www.DeepL.com/Translator (free version)

26

THE TENNER & THE PIPIT
They are two QRPp minimalist transceivers developed using the OXO described above, andthe SBL 1 mixer, with a direct conversion receiver. The Tenner is designed for the 10 meter
band, the Pipit is designed for the 15 meter band.
Here is the link to The Tenner and The Pipit , by G3XBM.Here is the Tenner (10 meterstransceiver):

Here is the Pipit (15 meters transceiver):

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THE 49’ER
Find the references on:
http://www.norcalqrp.org/files/49er.pdf
Unfortunately the kit is no longer available, by the will of the author, N6KR, who holds the
copyrigth. So no one can reproduce it for commercial purposes. However, personal
construction is possible. In fact, the author thinks that, with the advent of the "38 special" andthe SST, there are better circuits to apply to.
The diagram shows a transmitter with VXO tuning, with quartz for the 40 meters (as usual
you move a few kHz). The final transistor provides about 1 watt of power, and is a 2N3866.
As a receiver it uses the NE602 Mixer (18 dB gain), with a parallel LC bandpass filter in front(i.e. not as narrow band as a quartz or ladder filter). The integrated audio is the classic
LM380N. There is no sidetone, nor automatic frequency shift in transmission.
Here is the schema of the transceiver, by N5XR.

29

Uu80b Transceiver by G3XBM

Curumin by PY2OHH and modification by ON4XMJ

30

4SQRP Cricket 80a

31

The 10 m Lesser Chirpy

32

FET Transceiver 80 m by G3XBM

33

Wispy-10 WSPR RTX

34

VK2ZAY version of XBM80-2

1944 one tube TRX

35

One tube amateur station, by W9SCH

36

The Bell Ringer, 20 m RTX by AA1TJ

37

The MAS-Transceiver by DK1HE

The Pititico

38

The JU-6 7-14 MHz Transceiver by G3DOP

39

RTX Polevik by RA3AAE

RTX Polevik 20 + 40 by R2DNN

40

TRX 40 m by R2DNN

41

MAS 2013

One transistor transceiver by KV6Z

42

HA4OO Transceiver

DSB microtransceiver

43

DSB microtransceiver 21 MHz

44

The Gnat 40 RTX
One transistor transmitter, and one transistor regenerative receiver!

T2 is a simple 1:1 transformer made with 4 turns of #30 bifilar wire wound on a Fair-Rite 2843002402 binocular core45

Polish NE612 DSB Transceiver

46

47

Mosquito TRX

48

Transmitters
THE OXO:
It's a simple transmitter designed by GM2OXX. It consists of 3 transistors, and has VXO.
The output power is about 1 watt. It can be considered as a basic module and then build
other RTXs by putting together a receiver module. There are various projects that do this,always available on the net, and very instructive to read and study.

49

30 m QRPp TX by DL6ZB

50

THE NOGAnaut
100 mW transmitter, very simple; references on the North Georgia QRP Club link, by
KO4WX

VA3IUL TX

51

LU1AR RTX 10W 80m

52

The Michigan Mighty Mite

Minimalist transceiver that can deliver some from some milliwatt to 1 watt.

53

The Vanguard
The Vanguard is a simple one transistor transceiver (by Oleg Borodin, RV3GM), which cangive about 100mW or under 100mW. Mostly used in 20m and for QRPx.

54

One BJT Transmitter by K4TWJ

55

One Watt CW Transmitter

Ten Minute Transmitter

56

Four States QRP

One BJT Transmitter 700 mW

57

TX 5 MHz58

Little Joe59

TX and power amplifier

The Walnut TX by PA3DMI

60

Valvular TX

61

Emergency transmitter – A 8 components 10W 40m/30m TX by
SV3ORA

Components in grey are optional.

62

Russian transmitter “Paloma”

63

20 m 1 tube QRP Transceiver by UY1IF

64

Receivers
MTRX-20
It uses the NE602 as mixer and oscillator; it also uses the LM386 as audio amplifier. The
output power can be modified by adjusting C12.

The power is obtained with an oscillator based on 2N2222; quartz for the 80 meters.
The TX can be coupled with the "very simple" MRX-40 receiver modified for 80 meters:
http://www.arrl.org/files/file/Technology/pdf/80MRX40.pdf
With these two modules you can have a truly minimalist RTX!

65

MRX-30
A receiver for 30 meters.

66

MRX-40
A receiver for 40 meters.

67

1,5 V DC Receiver by DL6ZB

1 CHIP RX 80 m by G0FGI

68

A REGEN RECEIVER:

Russian DC RX

69

Russian DC RX 2

RX 69

70

Tiny SDR by LY1GP

71

Sudden Storm Receiver

72

The “Micro-Scope” - very simple 20 m D.C. RX for portable
operation
Oleg V. Borodin RV3GM P.O. Box 229, Lipetsk, 398043, Russia
For “W1FB” Memorial 2004
This is direct conversion receiver for 20 m band QRP calling frequency 14060
kHz. The mixer on opposing - parallel diodes here is used. The VXO generate thetwice-below frequency (xtal for 7030 kHz used).
Note this receiver may be used for any frequency exchanged components L1, C2, X1,
L2. Audio amplifier is brewed on well known LM386. Headphones or a small speaker 8
to 32 Ohms may be used. Components R1 C3 C4 are low-pass audio filter. Receiver
powered with 9 V batteries.

73

L1 & L2 wound on PVC cores 6 mm dia with ferrite screw, wires 0,27 mm dia. Bothinductors have 18 turns with tap from 5’th turn of the “ground” points. VD1&VD2 may
be any RF silicon type. Q1 may be 2N2222 or 2N3904.
Receiver brewed on a piece of PCB by “dead bug” method and may enclose to any
metal box or soldered on PCB material box.
72! de RV3GM

74

Utilities
Il Super VXO
Usually the oscillator of the above schemes using a variable capacitor can shift its oscillation
frequency by +/- 1 kHz or fraction of it; to have a higher bandwidth, of the order of 5-10 kHz
or even more, you can use a super VXO, where there are more quartzes in parallel on thesame frequency, and in series an inductor and a variable capacitor. Thie is a useful scheme,
by PY2OHH:

Audio Amplifier
If the audio signal of many proposed schemes is only suitable for headphone listening, it canbe remedied with a small and cheap audio amplifier based on the TDA2003.
The TDA2003 was born as a car audio integrated amplifier, from about 10 watts; theschemes of use are very simple and two of them are reported; the supply voltage includes
12 - 13.8 V, but can be even higher (refer to the datasheet).

75

76

S-meter circuit

77