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Amateur Radio & Electronics Projects:
144 MHz VHF AmplifierTri-Ex Tower InstallationLow Frequency DDS Transmitter
Denis P. Cote W1WVPortfolio Presentation
VHF POWER AMPLIFIEROverview
n Built 1995-1997n 144-147 MHz n CW & SSB Modesn Class AB Operationn 10 Watt RF Inputn 400 Watt RF Outputn Custom Machined &
Labeled Panelsn HV Safety Interlocks
Amplifier DocumentationDouble Click to Open Files
Microsoft Word Document
Detailed Description Write Up
Amp Fig. 1 HV PS Fig. 2a LV PS Fig. 2b Tube Data Sheet
VHF POWER AMPLIFIERComponents Chassis
Screen / Grid / Filament Supply
4CX250R – Power TetrodeRF Deck & Tuning Controls
Tank Circuit Compartment
VHF POWER AMPLIFIERHigh Voltage Tube Supply
n HV Plate Supply – 4 KV 0.5A Output
n HV Adjustable via Autotransformer (Variac)
n Nominal Voltage 2 KV
n Step-Start Inrush Protection
n 300V Screen Supply
n Adjustable Grid Bias
n Low Voltage Supplies: T/R Relay, Indicator Lamps & Auxiliary Relays
VHF POWER AMPLIFIERPower Supply Nomenclature
300 V DC Screen and
Bias Supply
4KV HV Transformer
12 & 9 Volt DC Low VoltageTR Relay, Indicator Lamps, Aux Relays
HV Filter Capacitor Bank
Step Start Relays
HV metering shunt (not visible)
Variac
HV Rectifier Bridge
VHF POWER AMPLIFIEROperational Parameters – On Air Test
Plate Voltage (No Load): 2200 VDC
RF Input Power: 640W
Plate Voltage (Load): 1600 VDC
RF Output Power: 390-400W
Plate Current (No Load): 90-100 mA
Drive Input: 8-10W
Plate Current (Load): 390-400 mA
Plate Dissipation: 240-250W
Screen Current (Load): 30 mA
Class of Operation: AB1
Grid Current (Load): 0-1 mA
Efficiency: 62.5%
TRI-EX ANTENNA TOWERConstruction - 1999
Base Preparation& Concrete Pour
Electric Winch Control
51’ Extended
Base Design &
FabricationWT-51 Tower: 21’ Retracted Ht.
Antenna Tower
Concrete Tower Base – AutoCAD
Low Frequency DDS TransmitterConstruction
LF DDS TransmitterOverview
n Atmel AT90S2313 DDS Chipn Frequency 130 - 400KHzn Operate 160-190KHz LF Band (LOWFER)n Morse, QRSS (Slow CW), DFCW n 1 Watt Outputn Stable 12.6 MHz TCXO n PC Control via RS-232n DDS Programmable via Parallel Converter &
Atmel Software
LF DDS TransmitterLong Distant Receive CapturesVisual Morse Code Representation
Receptions Courtesy of:
W1TAG (John Andrews) Andover, MA (Left)
W3EEE (Steve Dove) Elm, PA (Right)
Extremely weak signals – inaudible through receiver speaker !
QRSS/DFCW FFT Receive Software:
Argo V1 Build 1.34 courtesy Alberto, I2PHD
www.weaksignals.com
Soundcard based receive software
LF DDS TransmitterTransmit Antenna and Final
n 50’ x 50’ Vertical Loop Antennan LF Class D Final Transmittern Part 15 FCC – 1 Watt to TX Antennan DDS Transmitter used as Exciter
LF Transmit AntennaTX ID ‘DPC’ Swansea, MA
LF Final Amp in Weather Tight Enclosure – 100’ from house
TX Loop Antenna
LF Final AmplifierClass D Switching Amp
LF Final Amplifier BoardUndergoing Bench Testing & Tune Up
Square Wave – Amp OutputSine Wave – Antenna Current
LF Receiving Equipment
23 Turn LF Receive Loop
23 Turn LF Receive Magnetic Loop
Low Frequency Receiver Icom IC-R75 ReceiverLoop Tune Control & LP FilterAntenna Rotor ControlPC 500MHz AMD: Argo V1 & SB16 soundcard
LF Receive Block Diagram
LF RXIC-R75
Loop Tune&
Pre-Selector
CRTPCw/
SoundCard
500 KHzLP
Filter
Loop Antenna
Aux.Line Out
PC Running Argo Software
Displayed InformationAs Received
LF CW Exciter
RS-232 Keyed Oscillator Freq 173.5 KHZKID Keyer IC12 VDC Supply VoltagePoint to Point SolderingVector Board
Back Up
RADIO ELECTRONICS PROJECTS
Amplifier Testing Class D LF Final Amplifier Board
Output Waveforms LF Exciter Receive Antenna Relay Board
HAM RADIO EQUIPMENT
HF ANTENNAS/GROUND
n Rohn Telescoping Tower Refurbishment2009-Present
70 foot TelescopingTower
n Rohn Telescoping Tower Refurbishment2009-Present
Roller and Sheave Machining