forty-oner-frontview.jpg (27186 bytes) Forty-Oner         forty-oner-rearview.jpg (27031 bytes)

                        front view                                                                                                                                                      rear view

This name and part of schematic are taken from 49'er   where 40 represents the band, and 9 is 9V battery to supply the rig.

"Forty - Oner"   means that one watt is produced on 40M band. The idea to build simplest and smallest working rig came to my mind after hours of surfing the Internet  QRP resources. But the simplest not necessary means comfortable to operate. So, after short negotiations with N6KR I have added to 49'er's original schematic: new VXO, sidetone, QSK, TX-shift and audio filter circuits.

forty-oner - schematic.jpg (100385 bytes)

"Forty - oner" schematic  MS Paint-ed on my 49'er birthday :'-)) 


Forty-oner-prototype.jpg (199316 bytes)

"Forty - oner" - protype phase

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"Forty - oner" assembly finished, performing final tuning

forty-oner-ready to go.jpg (31051 bytes)

"Forty - oner" - inside view - ready to go !


Technical data and assembly comments

Supply voltage:    Typically 13,8V. Less voltage - less output power. Should work down to 7,5V.

Frequency range:    7000,8 kHz - 7037,4 kHz  ( QRP calling frequency in Europe is 7030 kHz )

TX output power:   Theoretically up to 1W, in practice 0,7 W or less. Use small heatsink on 3866.

Frequency stability :    Very good even on the edge of span, but FET follower is a must. Crystal's cases shall be soldered  and grounded. Use 10k helipot instead of ordinary potentiometer if you don't need fast tuning.

QSK&Sidetone :    Very useful but you must be aware of "knocking" into a speaker due to RF detection in AF amplifier  stage during transmission. Grounding pin 3 of LM386 helps but this require additional transmit/receive SPST switch (couldn't find the room for this ). Sidetone needs adjustment of signal level.

RX sensitivity:   Improved by adding serial R&C on pin 1 of LM386.

RX audio:    Excellent if you spend some time tuning AF filter. Small speaker is enough.

Antenna output:   Calculated for 50 ohms. For wire antennas use " Mini ATU "

Workload:     Two full week-ends If you have all components, case and your wife's agreement. Use  universal board for digital applications.

Efficiency report:    Using Inverted Vee antenna I 've made several European's QSOs with  RST 559 or better.


As I am real contester I made some Hams crazy and joined CQWW WPX with such a simple rig. To my great astonishment I made  38 contacts, and very few of them were tough. You'd better see my CTscreen.

wpx2001cw.jpg (163363 bytes)

Score is not important, however you can be sure that this will not be the check log.

26th of June 2002 UPDATE

Just received unexpected Award for the contest trial mentioned above. I like it !

wpx-award2001.jpg (19569 bytes)

If you have any questions how to build "Forty-Oner, just E-mail me.