Assembling ARDFrx2 v16 PCB.
Prevent problems, by BEFORE
placing and soldering :
CHECKING the value of every capacitor from the value text on it.
Warning : "100" could mean "10 followed by ZERO zeros" = 10pF NOT 100pF.
"104" means "10 followed by FOUR zeros" = 10,0000 pF = 100,000 pF = 100nF = 0.1 uF.
See a component value code table.
MEASURING the value of every resistor using a digital meter.
you use a DIY PCB :
Remember that your PCB does NOT contain metalized via's. A lot of connections function as feed-through between top and bottom.
This makes ground paths low inductance. And a small PCB possible.
You therefore HAVE to solder most connections at TOP AND BOTTOM.
The ground lugs of the coil housings also function as mass-feed-through. You MUST solder then also at top and bottom.
1. First solder all components having low
height and seating flat onto the PCB without space. (resistors, small
capacitors, connectors, headers, inductors).
Use only FILM capacitors for C3 and C46.
2. Then place all remaining bigger
parts (elco's, coil busses, crystal).
Connect the crystal housing quickly to mass to prevent radiation and hum. There is a special mass solder island near Xt.
REM: It could be necessary to place crystal Xt horizontally. See "Suggestions for housing".
Take the following anti-static measures, before soldering active components :
3. Temporarily solder TUNE
potentiometer middle connection "tune" to mass.
4. Temporarily solder GAIN potentiometer middle connection to mass.
5. Connect yourselves, and the soldering iron to a mass connection on the PCB.
The following measures prevent some oscillator frequency instability when the receiver is switched-on and IC1 warms up. :
Do NOT use an IC connector for IC1.
Put a little drop heath conducting compound onto the blank PCB surface under IC1.
Place IC1 in good contact with that PCB surface.
Solder IC1 staring with pin3 (GND).
6. Place one item at a time on the
top surface of the PCB, and solder at the bottom side :
D1, 2, 3, 4, Fet5, T1, IC1 en IC2 .
7. After that, solder onto the
bottom side of the PCB :
- SMD varicap CD1, Fet1 en Fet4.
- See correct positions (schematic).
The wide pin of FETs 1 and 4 is source. When soldered you should see the TOP side of them. Their legs are bended towards the PCB.
CD1 : the stripe is cathode. The other side (anode) is soldered to mass.
8. After that, check the correct solder flow of all components using a magnifying glass.
9. First connect external wiring (Tune, Gain, Led, Hp).
10. Only then remove the temporary grounding connections at TUNE and GAIN.
11. See "SETUP" for completing tests and adjustment of the whole receiver.