Silicon Chip – July 2019

siliconchip.com.au Australia’s electronics magazine July 2019 77

be generous with the solder.
Then install mini slide switches S5-
S9. The board is designed with slots
to suit their lugs, so you can solder
them right down onto the PCB. Again,
be generous with the solder to ensure
good joints.
The next job is to mount the LCD.
There are three possible headers to suit
different LCD module styles, although
Jaycar QP5516 or Altronics Z7018 are
the best fit.
For the Jaycar LCD, solder a 8x2-pin
DIL header to the row of pins nearest
the left edge of the PCB, then attach the
four short tapped spacers to the corner
mounting holes from the bottom of the
board, using 5mm machine screws.
You can then slip the LCD over the
pin header and attach it using four more
5mm machine screws, then solder the
header pins to the top of the LCD.
The procedure for the other LCDs
are similar except some LCDs may re-
quire short jumper wires to connect
to the PCB.
The final two components proper to
fit are rotary encoder RE1 and poten-
tiometer VR2. Mounting RE1 is easy;
make sure it’s perpendicular to the
PCB and pushed all the way down be-
fore soldering its pins.
Solder its five pins and two mount-
ing lugs; you will need a hot iron for
the latter, and be generous with the
solder.
For VR2, we’ve provided two dif-
ferent options. The prototype used a
16mm potentiometer with its body on
the underside of the PCB and its shaft
passing up through a hole.
Mounting it in this way is a bit fid-

Fig.7: autotransformer T1 is easy to
make, with just four bifilar turns wound
on the small ferrite balun core. AF
and BS are interchangeable and are
connected together on the PCB.

1 double-sided PCB, coded 04106191, 152.5 x 102mm

1 AD985x-based DDS module (MOD1)

1 PCB-mount barrel power socket (CON1)

1 SMA edge-mount socket (CON2)

1 2x3 pin header (CON3)

2 2-way pin headers (CON4)

1 jumper shunt/shorting block (JP1)

1 16x2 alphanumeric LCD with backlight (LCD1)

[eg, Jaycar QP5516 or Altronics Z7018]

1 500mm length of 0.8mm diameter enamelled copper wire (for winding L1-L3)

1 400mm length of 0.315mm diameter enamelled copper wire (for winding T1)

1 7mm ferrite balun core (for T1) [Jaycar LF1222, Altronics L5235]

1 PCB-mount vertical rotary encoder with integral switch (RE1) [Jaycar SR1230]

1 28-pin narrow DIL socket (for IC1)

2 10-pin headers (for mounting MOD1)

1 16-pin SIL or 8 x 2 DIL header (for LCD)

4 6.3mm long M3 tapped Nylon spacers (for LCD)

8 5mm M3 panhead machine screws (for LCD)

2 black PCB-mount momentary pushbuttons (S1,S2)

[eg Jaycar SP0721, Altronics S1096]

1 red PCB-mount momentary pushbuttons (S3) [Jaycar SP0720, Altronics S1095]

5 DPDT mini slide switches (S4-S8) [Jaycar SS0852, Altronics S2010/S2020]

1 9mm diameter knob to suit VR2

1 28-34mm diameter knob to suit RE1

1 0.5mm thick tin plate or cleaned tin-plated steel cans (eg, a large Milo tin lid)

2 0.8mm thick aluminium sheets, 300 x 250mm

1 adhesive panel label, 157 x 107mm

4 small self-adhesive rubber feet

Hookup wire, misc. enclosure hardware

Semiconductors

1 ATmega328P microcontroller programmed with 0410619A.hex, DIP-28 (IC1)

1 7805 5V 1A linear regulator, TO-220 (REG1)

3 BC548 NPN transistors, TO-92 (Q1,Q2,Q5)

1 2N4427 NPN RF transistor, TO-39 (Q3)

1 BC327 PNP transistor, TO-92 (Q4)

2 1N4148 small signal diodes (D1,D2)

Capacitors

2 10μF 50V electrolytic

1 1μF 50V electrolytic

11 100nF 63V MKT

1 10nF 63V MKT

1 1nF 63V MKT or 50V ceramic

2 15pF 50V C0G/NP0 ceramic

2 10pF 50V C0G/NP0 ceramic

Resistors (all 0.25W 1% metal film)

4-band code 5-band code

2 470k yellow violet yellow brown or yellow violet black orange brown

1 270k  red violet yellow brown or red violet black orange brown

4 10kΩ brown black orange brown or brown black black red brown

1 3.9k  orange white red brown or orange white black brown brown

1 2.7kΩ red violet red brown or red violet black brown brown

6 1k    brown black red brown or brown black black brown brown

1 820   grey red brown brown or grey red black black brown

1 390 orange white brown brown or orange white black black brown

5 220 red red brown brown or red red black black brown

8 56 green blue black brown or green blue black gold brown

2 47    yellow violet black brown or yellow violet black gold brown

2 27    red violet black brown or red violet black gold brown

1 10k mini horizontal trimpot (VR1)

1 500 9mm vertical PCB-mount or 16mm standard potentiometer (VR2)

Parts list – HF/VHF RF SIGNAL GENERATOR