The transceiver described here is remarkably simple based
on popular communication building block MC1496. It is fairly simple
to build because most of the functions are performed by MC1496. The
emphasis during the design of the project was on repeatability, minimum
number of switching and ability to modify for multi band operation.
In the beginning I would like to say that none of these
circuit ideas are totally original and are taken from various books
and magazines.
The circuit uses easily available components. Most of
the coils are wound on low cost balun core. The circuit uses ladder
filter. Filter is build around four numbers of 4.43 MHz crystals.
I used ladder filter because it is cheap and getting reasonably good
reports.
The circuit uses two numbers of MC1496. First MC1496
functions as receiver mixer cum balanced modulator. Second MC1496
works as product detector cum transmit mixer. The block diagram of
the transceiver is given below.
Presently the circuit is only for 7 MHz SSB operation.
It can be modified for other bands by suitably changing VFO, transmit
band pass filter and receiver band pass filter. I had avoided CW and
AM provision for simplicity. CW and AM can be implemented by making
some carrier to leak through balanced modulator. This can be done
by offsetting balanced modulator by applying some external voltage
to pin 4 of MC1496.
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.
600
Volt Power Supply - simple 600 Volt DC power supply. Convert
230V AC to 300V and 600V DC.
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.
Simple
RF Power Meter - simple RF power meter cum dummy load for
low power transmitters.
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.
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