External Connections Introduction
To connect the Softrock Lite V6.2 to the outside world, you will need to provide three connections:
- The first, and most obvious, is the power connection of your choice;
- the second, is the antenna connection;
- and the third is the I and Q output connection.
External Connections Bill of Materials
External Connections Summary Build Notes
- Install Power Connection
- Install Soundcard (I/Q) Connection
- Install Antenna Connection
- Test the Stage
External Connections Detailed Build Notes
Top of the Board
Install Power Connection
- Connect DC power leads to the pair of plated through-holes just below D1 on the left edge of the board.
- The plated through-hole nearest to D1 is the positive connection to a DC power source and the lower of the two plated through-holes is the power supply negative connection or circuit ground.
Install Soundcard (I/Q) Connection
A stereo audio cable may be connected at this time to the board at the three plated through-holes along the lower left edge of the board near the lower left corner.
- Use a short piece of #22 bus wire to connect the middle plated through-hole (ground) to the shield (barrel) of the cable and wrap the end of the bus wire around the outside of the cable several turns for strain relief of the cable.
- The tip of the stereo cable plug connects to the plated through-hole that is marked with the letter T on the board
- The ring of the stereo cable plug connects to the plated through-hole marked with the letter R.
The 30m, 20m, and 17/15m kits use 1/3 sub-harmonic sampling. This results in the I and Q signals for those kits being reversed. Consequently, if you are wiring the connections for one of these higher band kits, reverse the preceding wiring instructions. The photo below shows the wiring for the lower band kits.
Install Antenna Connection
It is extremely important to use an antenna with as close a match as possible to 50 ohms impedance. The radio's sensitivity is predicated on a 50 ohm antenna input.
- Connect a length of 50 ohm coax to the antenna connection on the right edge of the board near the upper right corner.
- The upper of the two plated through-holes is the antenna return connection to the coax shield
- The lower plated through-hole is the coax center conductor connection.
You may want to review the series of messages on this subject in the Softrock 40 Yahoo Group.
Additionally, you should review the materials on the Clifton Labs website concerning the use of an antenna isolation transformer
Finally, regarding the "floating antenna RET" connection, review the messages in this topic where the builder was getting no signal and the cause was the improper ANT RET connection.>
External Connections Completed Stage
Top of the Board
External Connections Testing
Radio Test - Generated Signal
The Softrock is ready to receive now. The first test, before connecting to an antenna for off-the-air signals, is to set up Rocky for 40m operation, connect the I and Q outputs to the stereo input of your sound card, and inject a signal into the radio's antenna terminals
Rocky setup and download instructions are available on the Rocky website
- Set up a signal source (the author used the the Norcal S9 Signal Generator) to generate a 50 uV, 7.040 MHz signal into the antenna lead.
- Run Rocky 3.2 with the center frequency set to 7.056 MHz.
- The results are as shown in the graphic below.