Assembly Manual for VFO Board 2 August 2018

Transcription

1 Assembly Manual for VFO Board 2 August 2018 Parts list (Preliminary) Arduino 1 Arduino Pre-programmed 1 Faceplate Assorted Header Pins Full Board Rev A capacitors 1 Rotary encode with switch 1 5-volt regulator 1 OLED Display mounted on faceplate 1 PCB 1 SI5351a premounted 1 27 MHz Crystal Ohm Resistors 4 1K Ohm Resistors 1 Push Button Switch 1 10K POT (Gain Control) 2 control knobs Assorted Header Pins The purpose of this board is to replace the original Control board and the Oscillator board of the Sandwich allowing for improved connection to the OLED display. The Gain Control is also replaced. Where possible, the assorted pin headers are placed where needed and trimmed to fit. A) The yellow header pin is used for I2C bus connections to the A4/A5 pin hole on the Arduino. 1

2 Blank board Front Blank board Back Steps for Assembly Front Side Assembly Solder the three (3) 104 capacitors where shown. Solder the Rotary encoder as shown. Solder the Gain Control as indicated. Solder 5 right angle header pins with plastic removed to holes for 8- V and GND as shown. Figure 1 shows PCB completed Front Side The Front of the PCB is now complete. 2

3 Back Side Assembly Solder the Voltage regulator to the back side of the PCB as shown in Figure 2. Vin pin is toward the center of the board while the GND pin is near the top edge. Note that the SI5351 SMD is already mounted. Solder the 27 MHz crystal. Solder the capacitors in place (0.1uf) (yellow in photo) Solder the ohm resistors as shown (Orange, Orange, Brown) Solder the 4 1K-ohm resistors as shown (Brown, Black, Red) Solder the Header pins as shown. o Yellow header pin is for I2C Bus and will extend through the Arduino for additional future options. o The 2-pin header pin on the top near the V-Reg is for JP10 functionality. o The 4-pin header, the 2-pin header and the remaining 4-pin header near the bottom are for connections to the Arduino. Figure 2a - VREG Figure 2 shows PCB completed Back Side Note: there are two soldered jumpers located near the Display pins. These are pre-soldered as appropriate for the voltage and ground configuration of the OLED display. 3

4 Mounting the Arduino. The 6 programming pins on the Arduino were previously assembled to allow for proper programming. The component side of the Arduino faces this completed PCB and slides onto the back of this PCB as shown in Figure 3. Solder the Arduino to the back of the completed PCB. Trim all header pins on the Arduino except for the 6-Pin Programming bus and the A4/A5 pins. Figure 3 shows PCB completed with Arduino mounted Mounted to faceplate 4

5 Calibration Calibration is quite simple, but you will need a frequency counter or an oscilloscope with digital read-out. A 9-volt battery and a couple of alligator clips are all that is needed. Calibration is easiest performed prior to placing the board in the main board. However, if the radio is fully operational, calibration can be performed at any time. Power must be supplied to the 8-VDC and GND pins on the Display PCB. PCB Not installed in the main board: 1) Connect a red alligator clip to the 8VDC pin (can be any color). 2) Connect a black alligator clip to the GND pin. 3) Orient the board as show in Figure 9 Figure 9 4) Connect the red (+) alligator clip to the + of the 9-volt battery 5) Connect the black (-) alligator clip to the of the 9-volt battery 6) The display will now show frequency. 7) Push and hold the TUNE Button for about 5 seconds 5

6 a. You will now be in BFO Freq Mode Figure 10 b. Adjust TUNE knob for about 0.5 KHz for USB or -0.5 KHz for LSB (first pass) c. Momentarily press the TUNE Button and this will store the value and cause you to enter the CRYSTAL CAL mode Figure 11 8) In the CRYSTAL CAL mode you are now ready to adjust the CAL frequency. a. Place the Signal Pin of your Frequency Counter on CLK1 pin located on the back top of the PCB as shown in Figure 8. b. Remember to Ground the ground pin of the counter (or Oscilloscope). c. Adjust the TUNE control until the Frequency Counter reads MHz or as close as you can find. Figure 12 d. Then momentarily press the TUNE Button to store the calibration which will also return you to Frequency Mode. 9) Calibration Complete PCB Installed in the Radio 1) Turn on the Radio with it connected to power 6

7 2) The display will now show frequency. 3) Push and hold the TUNE Button for about 5 seconds a. You will now be in BFO Freq Mode (Figure 10) b. Adjust TUNE knob for about 0.5 KHz for USB or -0.5 KHz for LSB (first pass) c. Momentarily press the TUNE Button and this will store the value and cause you to enter the CRYSTAL CAL mode (Figure 11) 4) In the CRYSTAL CAL mode you are now ready to adjust the CAL frequency. a. Place the Signal Pin of your Frequency Counter on CLK1 pin located on the back top of the PCB as shown in (Figure 8). b. Remember to Ground the ground pin of the counter (or Oscilloscope). c. Adjust the TUNE control until the Frequency Counter reads MHz or as close as you can find. (Figure 12) d. Then momentarily press the TUNE Button to store the calibration which will also return you to Frequency Mode. 5) Calibration Complete Calibration can be performed as needed but should only need to be performed once. Final PHASE Note the I2C bus connections at pins A4 and A5 on the Arduino are for future I2C bus usage. (presently used with LCD/Battery Pack Option) Mount the completed PCB to the Main PCB of the SSB Radio as shown in Figure 4: 7

8 Figure 4 PCB mounted on main board Figure 5 Main PCB Figure 5 shows the holes on the main board for connections. Board should be flush with the main PCB. Solder the 5 pins in place and trim them. The OLED display is pre-mounted to the faceplate. Slide the faceplate over the control knobs and slide the 4 pins from the OLED display into the 4 holes on the top of the front of the new PCB. Once in place, secure the Tune Control with supplied mounting screws. Solder the OLED in place on the back of the PCB. Trim wires Slide the black 6 pin protector onto the programming pins of the Arduino if it had been removed. This will help prevent the Arduino from accidently shorting. You need to solder two wires (white) as shown. 8

9 Front view of the mounted front panel. Figure 6 Example of placement of the OLED screen Figure 6. Figure 7 Board mounted inside radio case Yellow wires shown connect to JP10 for Dual Band Option. (Not Needed with new Push Button) Two White wires are for BFO and Fundamental Clock. OSCILLATOR BFO Solder the two white wires to the PCB (wires can be any color) Connect the white wire on the left to the BFO on the main PCB Connect the white wire on the right to the OSCILLATOR section on the main PCB 9

10 BACK Figure 8 pin connections Identified Note: There are different meanings for VCC on these circuits. a) Raw on the Arduino is 12 to 7 volts DC. We use 8.0 volts. b) VCC on the Arduino is 3.3 volts DC. c) The VDD voltage on the SI5351A is 3.3 volts DC d) VCC on the OLED is 5.0 volts DC. All these voltages are applied properly through the PCB and connections. 10

11 Figure 13 Additional Information: This jumper is pre-soldered based upon OLED shipped with package. OLED wire GND VCC jumper wiring OLED wire VCC GND jumper wiring Additional Suggestions: Thanks to B. Bartosh K6BWB for these added suggestions and photos. Attach a scope probe to the CLK2 Pin on back of VFO board (BFO output), and the probe ground to the ground. See Figure 8 above. Set the probe to x10, and measure the pk-pk amplitude of the signal and its frequency. The BFO frequency should be fixed at MHz. 11

12 Here is what the BFO signal should look like: On a spectrum analyzer the BFO signal should look like this: Attach the scope probe to the pad at CLK0 (VFO output). Measure the pk-pk amplitude of the signal and its frequency. The VFO frequency should be the sum of the fixed BFO frequency, MHz, and the desired tuning frequency. Table 1 shows this relationship. 12

13 With the tuning frequency set to MHz here is what the 20m VFO signal should look like: On a spectrum analyzer the VFO signal should look like this: 13

14 Note the spectrum analyzer frequency reading is typically more accurate than the period markers for the scope. If you have a spectrum analyzer it will be easy to see the VFO frequency shift as the tuning knob is rotated. You can also check that the tuning sensitivity changes after momentarily pushing in the tuning knob. Each push switches the tuning sensitivity to either 10 Hz or 100 Hz per "click" of the tuning knob. With the tuning frequency set to MHz here is what the 40m VFO signal should look like: 14

15 On a spectrum analyzer the VFO signal should look like this: The next thing we want to do is to adjust the calibration of the Si5351a chip so that its frequency output is exactly what we think it is. We do that by entering into the "Crystal Cal" mode of the Sandwich, monitoring the resulting 10MHz calibration signal that is output from the Sandwich, and using a frequency counter adjust the frequency to as close to MHz as possible via the tuning dial. Then press the tuning knob quickly once more and the display will show "Crystal Cal:" The 10MHz signal at CLK1 should look like this: 15

16 On a spectrum analyzer the 10MHz signal should look like this: It looks like it is dead nuts on 10MHz but we need better resolution of frequency so we use a frequency counter with 6 digit accuracy. You can attach your scope probe BNC connector to the counter to measure the frequency. My particular Sandwich showed this before calibration: So for sure the frequency needs to be adjusted. Turn the tuning knob until you are as close to 10MHz as possible. Use the highest resolution of your counter. The best I could achieve, within one "click" of the tuning knob, was either and MHz, so I chose MHz. When you are satisfied with the calibration push in the tuning knob momentarily and the Sandwich will return to the band tuning mode and remember the calibration. 16

17 Sandwich Full Schematic Arduino not shown in schematic 17