This blog documents the assembly and the testing of a SoftRock RXTXv6.2 - 40m/30m kit by DF7TV from September to November 2007. Please note that it reflects only the way I built my kit -- for your own assembly you should follow the official "builder notes" provided by Tony, KB9YIG for your kit. There also is a related discussion group at yahoogroups called "softrock40".

Some further information about the kit built by DF7TV is available from other sites (please be patient -- the download from my site at QSL.NET may be very slow):

• A document (pdf) with some figures and drawings concerning my RXTXv6.2 - 40m/30m transceiver. This document includes some figures which I prepared for my understanding of the transformers T1 to T4. I used the system of notation found in the builder notes concerning "first/second" and "primary/secondary" windings of these transformers. It also includes an illustration of the semiconductor pin-outs.
   
• Data sheets of the semiconductors used in this kit (I added also some of the semiconductors which may be used for individual modifications) may be downloaded from my K2 Semiconductor Data Sheets page.
   
• For the installation of U1 to U8 (except for U4) I prepared an illustration showing the designators and orientations of the ICs on the bottom side of the RXTXv6.2 PCB:

  

   

• ...And here is a photo of the setup used for first QSO with F2YT, Paul on the 40m band.

   

•  Finally there is a photo of the populated top side of the RXTXv6.2 40m/30m circuit board:

2007-09-04:

The kit arrives; TNX Tony!

2007-09-05:

Inventory according to bill of materials RXTXv6.2 BOM 40m 30m 6_28.pdf. All parts are present and in good shape :)

2007-09-07:

Studied the schematics and builder notes.

2007-09-08:

Installed half of the 0.1uF SMD caps on the bottom side of the board. Thanks to the heat traps at the ground pads I had no problems doing that. In fact it worked out to be much easier than I thought it would be.

2007-09-09:

• Now all 0.1uF SMD caps C50 to C73 are installed.
• Installed the following ceramic capacitors: C2, C9, C4, C11, C43, C6, C8, C13, C15, C18, C21, C23, C22, C37, C36, C38, C39, C40, C41, C45.
• The ceramic capacitors C19 and C24 will be installed later.
• Installed the following electrolytic capacitors: C3, C10, C16, C17, C20, C25, C26, C27, C28, C29, C30, C31, C32, C33, C34, C35, C42.
• The electrolytic capacitors C1, C5, C7, C12 and C14 will be installed later.
• Installed the following resistors: R1, R2, R49, R53, R35, R36, R29, R30, R48, R52, R58, R3, R4, R6, R7, R9, R10, R12, R13, R41, R45, R55, R56.

2007-09-10:

• Installed the following resistors: R5, R8, R11, R14, R19, R20, R44, R15, R16, R18, R22, R25, R33, R17, R23, R24, R26, R27, R42.

2007-09-11:

• Installed the following resistors: R28, R40, R43, R59, R31, R32, R34, R38, R57, R60.
• The resistors R21, R37, R39, R46, R47, R50, R51 and R54 will be installed later.

2007-09-12:

• Installed the following diodes of type 1N4003: D2, D1, D3.
• Installed the voltage regulator of type 78L05AC: U4.
• Connected a 12V power supply and measured the following voltages in Volts (voltages are always measured with reference to ground except where otherwise stated). The measurements are shown as "[value expected/value measured]": At the center of the board: 12V-testpad +12V [11.3/11.3] Left of U4: 5V-testpad +5V [5/5.02] U4 pin in [11.1/10.9], U4 pin out [5/5.02], Q9 pin collector [11.3/11.3], Q10 pin emitter [11.3/11.3], U1 pin 8 [5/5.02], U2 pin 8 [5/5.02], U3 pin 16 [5/5.02], U5 pin 14 [5/5.02], U6 pin 14 [5/5.02], U7 pin 16 [5/5.02], U8 pin 8 [5/5.02].
• Measured supply current: 9 mA.
• Disconnected the 12V power supply.
• Installed the following transistors of type 2N3904: Q13, Q4, Q11, Q9, Q12.
• Installed the following transistors of type 2N3906: Q14, Q10.
• Connected a 12V power supply and measured the supply current: 9 mA.
• Disconnected the 12V power supply.

2007-09-14:

• Selected the crystals to be installed as X1 and X2 on this board: X1 = 28.060 MHz and X2 = 40.500 MHz.
• Soldered one short blank wire to the case of X1 and one to the case of X2. These wires are used to connect the cases of the crystals to ground.
• Between the case of each of the crystals and the board I inserted a self-retaining thin crystal-insulator.
• Installed X1, X2.
• Measured the resistances from the "hot" end of X1 and of X2 to ground. The measurements are shown as "[value expected/value measured]": JP2 pin 1 to ground [>10 MOhm/>10 MOhm], JP2 pin 3 to ground [>10 MOhm/>10 MOhm].

2007-09-16:

• Installed three-pin header JP2.
• Installed R54.
• Connected a 12V power supply and measured the supply current: 18 mA.
• Measured the crystal oscillator output frequencies at the emitter of Q14. X1 or X2 are selected by the jumper plug at JP2: f_osc[X1] = 28.059 MHz, f_osc[X2] = 40.499 MHz.
• Disconnected the 12V power supply. Set the jumper plug at JP2 for selection of X1.
• Installed a wire bridge to connect JP1 pin 1 to pin 2.
• Installed a test point header at JP1 pin 4 (ground).
• Installed Q1, Q7 and Q8.
• Prepared the leads of Q3, Q5 and Q6 for installation. Put a small amount of heat conducting paste at the locations on the top side of the pcb where the rounded part of these transistors will be located to improve heat conduction from this side of the transistors to the ground plane of the board.
• Installed Q3, Q5, Q6 and the related Sil-pad and TO-220 heatsink.

2007-09-23:

• Installed transformer T1.
• Slipped a short -- about 1/16 inch long -- piece of insulating tube on each of the wires of the first secondary winding of T2 so that the core is stabilized against the board once these wires are pulled and soldered.
• Installed transformer T2.
• Pressed the T-18 heat sink onto transistor Q2 (2N2222A) using a small amount of heat conducting paste between Q2 and the heat sink. Slipped the transistor leads through the #4 nylon washer used as a spacer.
• Installed transistor Q2.

2007-09-25:

• Installed RF choke RFC1.

2007-09-26:

• Wound the remaining inductors and transformers. [For T3 I temporarily tried to use a FT37-43 but during transmitter tests (see 2007-11-04) I returned to the original binocular core and winding scheme as given in the builder notes (which works fine).]

2007-09-27:

• Measured L1 = 9.0 uH Reduced number of turns of L1 from n=47 to n=45 Measured L1 = 8.3 uH
• Installed L1.
• Measured L2 = 0.88 uH Reduced number of turns of L2 from n=16 to n=15 Measured L2 = 0.79 uH
• Installed L2.
• Measured L3 = 0.88 uH Reduced number of turns of L3 from n=16 to n=15 Measured L3 = 0.80 uH
• Installed L3.
• Measured inductance of T4 primary winding L = 0.50 uH Reduced number of turns of T4 primary from n=11 to n=10 Measured L = 0.45 uH
• Installed T4.
• The inductor L4 and the transformer T3 will be installed later.

2007-09-28:

• Connected a 12V power supply.
• Measured supply current: I=18 mA.
• Measured the following voltages in Volts (voltages are always measured with reference to ground except where otherwise stated). The measured values are shown as "[value expected/value measured]": C20 pin + [11.3/11.3], C16 pin + [2.5/2.51], C17 pin + [2.0/2.01], U7 pin 1 [5.0/5.01], U8 pin 3 [2.5/2.5].
• Disconnected the 12V power supply.

2007-09-30:

• Installed the ceramic capacitors C19, C24.
• Installed the following electrolytic capacitors: C1, C5, C7, C12, C14.
• Installed the following resistors: R21, R37, R39, R46, R47, R50, R51.
• Measured L4 = 2.07 uH Reduced number of turns of L4 from n=22 to n=21 Measured L4 = 1.83 uH
• Installed the inductor L4.
• Connected a 12V power supply.
• Measured supply current: I= 18.6 mA.
• Disconnected the 12V power supply.
• Slipped a short -- about 1/16 inch long -- piece of insulating tube on each of the six leads of T3.
• Installed the transformer T3.
• Connected a 12V power supply.
• Measured supply current: I= 18.6 mA.
• Disconnected the 12V power supply.
• Installed the IC U5.
• Connected a 12V power supply.
• Measured supply current: I= 28.3 mA.
• Measured the output signal at U5 pin 5, 6, 8 and 9 to be a rectangular signal of frequency f= 14.0294 MHz.
• Disconnected the 12V power supply.
• Installed the IC U6.
• Connected a 12V power supply.
• Measured supply current: I= 33.2 mA.
• Measured the output signal at U6 pin 5, 6, 8 and 9 to be a rectangular signal of frequency f= 7.01467 MHz.
• Disconnected the 12V power supply.
• Installed the IC U7.
• Connected a 12V power supply.
• Measured supply current: I= 34.1 mA.
• Measured the input signal at U7 pin 2, 14 to be a rectangular signal of frequency f= 7.01468 MHz. (The phase difference between these two signals was measured to be about 37 ns).
• Disconnected the 12V power supply.
• Installed the IC U8.
• Connected a 12V power supply.
• Measured supply current: I= 35.1 mA.
• Disconnected the 12V power supply.
• Installed the IC U3.
• Connected a 12V power supply.
• Measured supply current: I= 35.5 mA.
• Measured the input signal at U3 pin 2, 14 to be a rectangular signal of frequency f= 7.01467 MHz.
• Disconnected the 12V power supply.
• Installed the IC U1.
• Connected a 12V power supply.
• Measured supply current: I= 36.5 mA.
• Disconnected the 12V power supply.
• Installed the IC U2.
• Connected a 12V power supply.
• Measured supply current: I= 37.8 mA.
• Disconnected the 12V power supply.
• -- The installation of all parts of the kit is complete. --
• PTT Test: Connected a 50 Ohm resistor to ANT. Connected I_PTT to PWR_+. Connected a 12V power supply. Measured supply current: I= 144 mA.
• With I_PTT connected to +12 Volts: Measured the voltages across the source resitors of the PA transistors: V_R31 = 61 mV, V_R32 = 57 mV These values correspond to a quiescent current of about 27 mA at each of Q5 and Q6. Measured the voltage across the emitter resistor of Q2: V_R24 = 1.20V This value corresponds to a quiescent current of about 21 mA at Q2. Measured the temperatures of Q2 and at the TO-220 heat sink of Q5, Q6 to be at about T = 45 degrees Celsius (ambient temperature at about 21 degrees Celsius).
• Disconnected the 12V power supply.

2007-10-07:

• Installed the software Rocky3.32 from Alex, VE3NEA on a laptop computer.
• The laptop's data are: Processor: Intel Pentium M processor/Centrino clocked at 1.70 GHz equipped with 1GB of RAM, (An RS-232 interface is available at the docking-station) Sound cards: SoundMax Digital Audio, Analog Devices (internal); USB Sound Blaster MP3+ (SB0270), Creative (external), Operating System: Windows XP, Service pack 2, Microsoft.

2007-10-16:

• Received first CW-signals on the 40m band.
• The same station appears two times (symmetrical about the f_osc/4 - frequency in the spectrum -- so it seems that I have a little problem to be solved).
• Thanks to Bodo, DJ9CS the little problem was solved within a quarter of an hour. I connected the RXTXv6.2 to the microphone input, which most probably is not stereo. So now with the RXTXv6.2 output connected to the stereo LINE input of the MP3+ signals are popping out of the speakers loud and clear and the symmetry is gone.

2007-10-17:

• Replaced the 30m-crystal X2 by the second 40m-crystal. In that way my RXTX will cover not only the CW-only part of the 40m band here in DL but I'll also be able to do some experiments in the Digimode/SSB part of this band (my MP3+ USB sound card allows only for a 48 kHz range with each crystal). Additionally my indoor loop antenna works very well on 40m but not as well on 30m. And last but not least 40m is the band I like most -- perhaps because I had a lot of QRP-CW QSOs on this band using my K2 @ 5Watts output. So my "40/30m" transceiver now changes to be a "40m-only".
• [nominal values of the crystals used now are: f_crystal_X1 = 28.060 MHz, f_crystal_X2 = 28.224 MHz]
• Measured the frequency present at the U7, the QSD circuit of the RX-part at pin 14 to be: U7, pin 14: f_X1/4 = 7.01473 MHz, f_X2/4 = 7.05567 MHz These frequencies are believed to be correct within +/-50Hz and will be entered in the settings of the software Rocky 3.32.

2007-10-28:

• Preparing the kit for a first TX-Test.
• Assembly of a "Paddle-to-RS-232" interface as published in the magazine-article "SoftRock RXTXv6.1: ein software-definierter QRP-Transceiver", Dr.rer.nat. Thomas Baier, DG8SAQ and Dr.-Ing. Bodo Scholz, DJ9CS, Funkamateur, June, 2007, page 608 to 612. The "Funkamateur" is a german magazine for radio amateurs. This interface differs from the one published on the Rocky 3.32 site(see dxatlas.com/rocky/Paddle.gif). In the circuit published within the Funkamateur article the "hot ends" of the dot and dash switches of the paddle are not connected directly to the DSR (6) and CTS (8) pins of the RS-232 jack. By the use of two general purpose PNP-transistors (I used the Philips BC557C here) and four additional resistors the dot and dash switches are connected via these transistors to the RS-232 jack. Thus it is possible to connect the common lead of the dot and dash switches to ground.

2007-10-31:

• Download and installation of the Double Tone IQ-Generator IQGEN program (audio frequency 0 to 24 kHz) by DL6IAK, Michael Keller to be used during transmitter tests.
• IQOUT by M0KGK, Duncan Munro is an alternative program for audio IQ signal generation.

2007-11-03:

• Temporarily connected a BNC jack to the RXTX Ant output.
• Set up IQGEN to provide a 5kHz, 2.4Vpk-pk audio output signal, checked left and right channel to be about 90 degrees out of phase. Noting the position of the speaker level knob for the 2.4Vpk-pk. Reducing the output to zero.
• • Connected a 50 Ohm dummy to the Ant output.
• Connected a 12V supply to the RXTX. Measured the supply current to be I = 37.5 mA.
• Connected a 12V to the I_PTT. Measured the supply current to be I = 142 mA.
• Disconnected I_PTT.
• Connected the "L" pad on the transceiver to the left channel output, the "R" pad to the right channel of the audio output.
• Connected a 12V to the I_PTT. Measured the supply current to be I = 142 mA.
• Slowly increased the audio level up to when the supply current is I = 250 mA WOW -- I got an RF output at 7060 kHz! Switched on my Sangean ATS 909 shortwave receiver to listen to the first signal leaving my RXTX.
• Because the output power does not increase as much as expected when I increase the audio level (...but the supply current does) I think that it was perhaps not a good idea to modify T3 (see 2007-09-26).
• Now that I wound transformer T3 according the builder notes I got a RXTXv6.2 which is transmitting with a bit more than 1 Watt output power at about 330 mA supply current.
• A big THANK YOU! to Tony, KB9YIG et al. for designing and making available this kit as well as to Bodo, DJ9CS and the softrock40 group at yahoogroups for the help -- building this kit was a very satisfying experience.
• 73 -- I hope to meet you on the bands! Thomas, DF7TV.

2007-12-09:

• Postscript: Today I had my first QSO with the SoftRock RXTXv6.2 - 40m/30m. I worked Paul, F2YT (a very friendly and active french ham which I personally know from a meeting at the Côte d'Azur) on the 40m band using the setup described within the blog entry of 2007-10-07. The antenna was an indoor loop antenna of about 12mtr perimeter, coupled via an homemade balun and the Elecraft T1 tuner to the SoftRock. The T1 tuned nicely even with the only about 1 Watt output power of the SoftRock. Future practical experiments will be done partly at DK0SU where I installed a Pentium 4, 1.9GHz / 1.5GB Ram computer, which together with a newly acquired external USB-sound card Sound Blaster Surround 5.1 (I think it is the successor of the "Live!" sound card) will serve as my platform at the clubstation. There we have a dipole and a vertical antenna for the 40m band which will surely help during future experiments. I hope to meet a lot of other "SoftRockers" on the band. 73, Thomas, DF7TV.