The 60 Watt linear amplifier is simple all solid state
circuit using power mosfet IRF840. The IRF series of power transistors
are available in various voltage and power ratings. A single IRF840
can handle maximum power output of 125 watts. Since these transistors
are used in inverters and smps they are easily available for around
Rs: 20/-.
The IRF linear amplifier can be connected to the out
put of popular VWN-QRP to get an output of 60 Watts. The circuit draws
700 ma at 60 Volt Vcc. Good heat sink is a must for the power transistor.
Alignment of the circuit is very easy. Connect a dummy
load to the out put of the circuit. You can use some small bulb like
24V 6Watts as the dummy load. I have even used 230V 60Watts bulb as
dummy load with my IRF840 power amplifier working at 120Volts. Adjust
the 10K preset to get around 100 ma Drain current. I used gate voltage
of 0.8V with my linear amplifier. A heigh gate voltage can make the
power transistor get distroyed by self oscillation. So gate voltage
must be below 2V and fixing at 1V will be safe.
Bifalar transformaer T1 is wound with 8 turns 26SWG on
1.4 x 1 balun core. The coil on the drain of IRF is 3 turns 20 SWG
wound on 4 number of T13.9 torroids (two torroids are stacked to form
a balun core). The RFC at the Vcc line is 20 Turns 20 SWG wound on
T20 torroid.
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7 MHz SSB Transceiver
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Linear Amplifier
used in 7MHz SSB Ham Radio Transceiver using 2N2222A, SL100B and BD139 |
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Hobby Circuits - Ham ( Amature ) Radio |
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7MHz
SSB Transceiver - Circuit digram and brief description of
7MHz SSB Transceiver for Hams. The circuit is designed around two numbers
of MC1496. It can push around 80 Watts with IRF840 in the final. You can
down load HTML version or the printer friendly word document. |
Morse
Code Tutor - A program (23kb) written in C++. Morse code
uses dot and dash for communication. Still it is popularly used for communication
is short wave bands. The Archive contains program source code and executable. |
AM
DSB Transmitter for Hams - circuit diagram of simple double
side band suppressed carrier (DSBSC) transmitter for hams. Circuit uses
crystal oscillator, crystal can be switched for multi band operation. |
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Ham
Radio BFO - circuit diagram of beat frequency oscillator
using BF494 and how to listen amateur radio communication on ordinary
BC receiver. |
Miniature
MW Transmitter - circuit diagram of simple medium wave transmitter
using BF494B. This simple transmitter have a range of 200 meters. |
807
and 1625 Valves - data on vacuum tubes 807 and 1625 used
in ham radio transmitters. Describes various pin voltages and different
operation modes. |
FM
Wireless Mike - low power frequency modulated transmitter
using two transistors. The circuit works with 9v power supply. |
60
Watt RF Amplifier - Soild state RF power amplifier using
IRF840. Simple and easy to construct. IRF840 can handle a maximum power
output of 125 Watts. |
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Touch
CPO - touch operated code practice oscillator using popular
timer IC555. Practice Morse code in a different way. |
Modulation
Monitor - very simple and useful circuit used to monitor
on air transmission of your low power amplitude modulated transmitter. |
Cheap
Crystal filter - Ladder filter using six 4.43MHz Crystals.
Building cheap side band filter for your bome brew SSB Rig. |
RF
Dummy Load - make this simple RF Dummy Load for off-air testing
of your radio transmitter. |
Mosquito
Repellant - very simple and easy to assemble mosquito repellant
using two transistors and handy components. |
Ceramic
Filter BFO - Receive SSB and CW transmissions
on your BC receiver. Simple BFO is build around 455 KHz Ceramic Filter. |
SSB
ADAPTOR - Build this simple adaptor to receive single side
band SSB on short wave AM receivers. |
QRP
Keyer - very simple keyer circuit using only one transistor. |
Designing
RF Probe - make your self simple and heighly useful RF probe.
An essential tool for every home brewer. |
Shorty
Forty Antenna - Do you have space limitaion to put a 40 meter
dipole. Try this Compact 40 meter antenna. |
