Assembling ARDFrx2 v16 PCB.
Prevent problems. BEFORE
placing and soldering :
MEASURE the value of every resistor using a digital meter.
CHECK the value of every capacitor from the text on it.
Warning : The last digit represents the number of ZEROS following the preceding number.
"100" could mean "10 followed by ZERO zeros" = 10pF and NOT 100pF.
"104" means "10 followed by FOUR zeros" = 10 0000 pF = 100,000 pF = 100 nF = 0.1 uF.
See also a component value code table.
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 on the PCB the
potentiometer connection "Tune mid" to "Tune minimum".
4. Temporarily solder on the PCB the GAIN potentiometer connection "Gain mid" to "Gain minimum".
5. Connect yourselves, and the soldering iron to a mass connection on the PCB (screw hole h2)..
If for FET5 a BF256b is used, you have to change the pinning sequence to fit the PCB. See photo ==>
Do NOT use an IC socket for IC1. Solder IC1 directly into the PCB.
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 . Solder the ICs starting with its ground pin..
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. Remove the temporary grounding connections at TUNE and GAIN.
11. See "SETUP" for completing tests and adjustment of the whole receiver.
12. The PCB should be screwed on holes h1 and h2 into a screening metal housing, with each two M3 nuts as spacers between housing and PCB bottom.
I used a 10-turn Helipot tune potentiometer i had in stock.
The component list mentions a cheaper and smaller Vishay type.
Do use it with a 10-turn scale knob.