About the article

3 GHz Frequency and Signal Level Meter

Built around a CPLD and a dsPIC microcontroller

3 GHz Frequency and Signal Level Meter

This handy instrument measures frequencies from 50 MHz to 3 GHz with an accuracy of 10 ppm and provides an indication of the signal level over a range of –40 dBm to +10 dBm. Readings are displayed on a three-line LCD module, and the instrument is powered by three standard AA cells.

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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info / Update

* Frequency measuring range: 10 MHz to 3 GHz
* Frequency measurement error less than 10 ppm (0.001%)
* Signal level measuring range: –40 dBm to +10 dBm (0.1 ?W to 10 mW into 50 Ohm) over the range of 300 MHz to 2.8 GHz
* 146 readings per minute
* Power source: three 1.5 V AA cells or a 5 V AC mains adapter (min. 180 mA)
* Maximum current consumption at 5 V input: 170 mA
* Battery life with three 2000 mAh NiMH cells: 18 hours continuous operation without LCD backlighting or 11 hours with backlighting

Component list
R101 = 56Ohm
R104 = 4.99kOhm
R105,R229,R231 = 0Ohm
R200 = 10kOhm
R201,R303,R308 = 47kOhm
R202,R211,R226 = 33kOhm
R203,R210,R301,R302 = 100kOhm
R220,R221,R222 = 15kOhm
R225 = 150kOhm
R230,R235 = 1kOhm
R232,R293 = not fitted
R236 = 18kOhm
R250,R25 = 39Ohm
R290,R291,R292 = 4.7kOhm
R304,R305,R306,R307,R404 = not fitted
R401,R402,R403,R405 = 18Ohm
R406 = 82Ohm
C101,C226,C230,C231,C232,C301,C302,C303 = 100nF
C102,C110,C403,C415 = 100pF
C104,C105,C233,C401,C402,C404,C413,C416,C418,C419,C422,C423,C425 = 1nF
C106,C109 = not fitted
C107,C108 = 1pF
C200,C201,C210 = 2?F
C202,C211,C251,C252 = 1?F
C240,C241 = 18pF
C250 = 470nF
L101 = 1.5nH
L401 = 4.2?H
D200,D201,D202,D205,D225,D226,D227,D228 = NSR1020 (SOD323-W)
D204,D235 = 3.3V zener diode (SOD123)
D206 = 5.6V zener diode (SOD123)
IC101 = LT5538
IC200,IC210 = MCP1824 (SOT23-5L)
IC230 = DSPIC33FJ32GP204-I/PT (TQFP44), programmed
IC301 = EPM240T100C3N (TQFP100), CPLD (Altera)
IC401 = LMX2485E (LLP24), PLL (National Semiconductor)
IC402 = ABA-31563 (SOT363), wideband amplifier (Avago)
Q250 = BSS123 or SN7002W (SOT23)
VR230 = TL431 (SOT23-5), voltage reference (TI)
IC250 = EA DOGM163W-A, 3.3V-LC-Display, 3x16 characters (Electronic Assembly)
JP001 = DC adaptor socket, PCB mount
JP100 = SMA socket, 142-0711-881 (Emerson/Johnson)
JP200 = (optional) 2-pin pinheader (battery connection)
JP230 = 2-pin pinheader with jumper (if required)
JP235 = 5-pin pinheader, right angled
JP301 = 6-pin pinheader, right angled
JP302 = 6-pin pinheader, 2-row (if required)
R205 = self heasling fuse 30V/0.2A (SMD1210), Littlefuse 1210L020WR (e.g. Farnell 1596997)
S200,S220,S221,S222 = pushbutton, 1 make contact, PCB mount
X240 = 18MHz quartz crystal (HC49/SMD)
X301 = CFPT-126 (LF TVXO009920) from IQD, temperature compensated 40MHz SMD quartz oscillator (Farnell #1100757)
Enclosure: Bopla Type BS404 F-7035
PCB # 100760-1
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