Taurus SSB transceiver

 

 

20m version

When Aquarius project became more popular many QRP-ers asked me if I could develop simple ( means duplicable) SSB version of low cost QRP transceiver. Having very limited  spare time for hobby I decided to do it anyway. Prototype phase launched on October 2004 then. The project was finished 20th of January 2005.  For many reasons the project is divided into three parts: RX, TX and display. Schematics diagram is rather simple and some of ideas were taken from Luc F6BQU under his kind approval. Digital readout is a local manufacturer's kit.

 

Prototype of RX board.

I have used  very covenient MC3362P chip again.

 

Final look of the RX part.

 I removed one crystal from the filter finally and changed all circuit.

So Taurus is equipped both with Cohn's and Butterworth's variations of crystal ladder filters.

 

Prototype is ready to go.

Separate PA stage was not necessary as well as I could get 4 watts from 2SC2078 transistor

 

And the day has come. 1st QSO with M3THB on 2 of January 2005

 

No

 Date UTC Callsign RS rcv'd Comments
1 02 Jan 2005 12:42  M3THB  46  First contact ! What a day...Too much drift of VFO ( more than 100Hz during QSO). Modulation was O.K - Barry said...
2 02 Jan 2005 13:29 SQ1ST/mm 57  Short QSO, no problem to copy except above
3 09 Jan 2005 14:02 DL4TE 58 Changed VFO coil. T50-6 instead T50-2. Good move
4 10 Jan 2005 18:28 SP5COK 59 Last BFO and carrier oscillator alignment. Microphone level optimised for various types of microphones
5 17 Jan 2005 16:45 SP5HRX 59 Short skip QSO, very low drift of VFO, but...
6 23 Jan 2005 15:01 MJ/PA3GIO/p 59 First QSO after final alignment of VFO ( drift less than 50Hz during standard QSO) and packing into case.
7 23 Jan 2005 16:22 OO7JA 51-54 Jan said - In unstable conditions your signal is very clear and stable. Good for Taurus !
8-28 29 Jan 2005 13:00 UBA Contest 59s Taurus performed fine during contest conditions. Could work even US station.

Taurus logbook with comments and evaluation

 

RX schematics for 20 meter band.

AGC reacts for very strong signals intentionally.

 

TX schematics for 20 meter band.

Good linearity of driver and PA stages. Diode based voltage reference - simple ;-))

 

Taurus inside view.

Digital readout is in the right bottom corner of the picture

 

Tarus front view

 

Tarus rear view

 

Technical specifications (general):

1.    Operating frequency band    -    14,100MHz - 14,350MHz

2.    Output power                      -    4W  ( strong whistle)

3.    Voltage supply                     -    13,8V

4    Microphones                         -    dynamic or electret

5.    Frequency stability              -    better than 50Hz after short warm-up

6.    RX sensitivity                      -    satisfactory ( not measured )

7.    Overall cost                        -    12 weekends and approximately 50 Euros for parts

 

 80m version

After succesful launch of Taurus 20, new version for popular 80m band was developed. No significant changes were done except IF which was chosen for 8MHz to remain VFO circuit unchanged. If you can read Polish you may download all files of Taurus project including 80m modifications from www.sp5ddj.prv.pl in apropriate Taurus section.

Some photos of Taurus 80 are shown below.

Taurus 80m - general look

RF Gain added ( simple 1k potentiometer)

 

Taurus 80m - inside front look

 

Taurus 80m - inside rear look

 

Taurus 80m - RX side

 

Taurus 80m - TX side

 

Taurus 80m - RX side - power meter

 

Good quality PCB's are available on E-mail request

The very first non-Polish  QRP Ham who started assembly of Taurus is Bob WB6KWT. You may watch his building progress visiting his very neat QRP website www.wb6kwt.com .