Rugged mechanical
construction is needed to
have an oscillator that does not
“microphonicly” respond to vibration.
That is the reason
I used #12 wire for the coil.
The circuit should be enclosed in
a metal box for shielding. A feed
through capacitor for power — like
Mouser 800-4400-007LF ($8.33) —
would be nice but is pricey. BNC
connectors for the outputs should
work well.
I made a layout (Figure 5) and
generated Gerber files which can be
downloaded at the article link in case
anyone wants to build it. Note: The
unconnected parts go to the ground
plane which is only shown as an
outline. Figure 6 is a sketch to show
what L1 should look like and Figure
7 is a Parts List. Sunstone Circuits will
build one board for $35.80. NV
10 METER VCO PARTS LIST
PART DESCRIPTION PKG MOUSER PART COST
IC1 LDO REG, ADJUSTABLE TO252 726-IFX27001TFV $1.52
Q1 MMBT4124 SOT23 512-MMBT4124 0.20
Q2, Q3 MMBTH81 SOT23 512-MMBTH81 0.22
C1 10 µF, 35V, 10% 7343 80-B45196E6106K409 0.73
C2, C3 0.1 µF, 50V, 10% 1206 81-GCM319R71H104KA7J 0.27
C4 33 pF, 250V, 5% 0805 581-UQCFVA330JAT/500 1.50
C5 27 pF, 250V, 5% 0805 581-UQCFVA270JAT/500 2. 10
C6 20 pF, 250V, 5% 0805 581-UQCFVA200JAT/500 2. 10
C7 1,000 pF, 50V, 10% 0805 581-08055A102J 0.10
C8 2. 2 pF, 250V, 5% 0805 581-UQCFVA2R2BAT/500 2. 30
C9 .01 µF, 50V, 10%, X7R 0805 80-C0805C103K5R 0.10
L1 500 nH, 2%, 9 TURNS #12 ON ½ INCH FORM, 1.1 INCHES LONG
ALL RESISTORS THICK FILM, 1%, 1/8W 0805 71-CRCW0805-VALUE-E3 0.07
■ FIGURE 7.
■ FIGURE 6.
September 2013 21
