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Tuned Radio Frequency (TRF) Receiver – Circuit Schematic
Tuned Radio Frequency (TRF) Receiver
Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world ...
Thunderstorm Predictor – Circuit Schematic
Thunderstorm Predictor
Sure, listening to VHF FM has great advantages over MW/LW AM from the old days ” now we have bright stereo free from interference, fading and noise! However, ...
Single-Chip VHF RF Preamp – Circuit Schematic
Single-Chip VHF RF Preamp
Here is a high performance RF amplifier for the entire VHF broadcast and PMR band (100-175 MHz) which can be successfully built without any special test equipme...
Simple Short-Wave Transmitter – Circuit Schematic
Simple Short-Wave Transmitter
This low-cost short-wave transmitter is tunable from 10 to 15 MHz with the help of ½J gang condenser VC1, which determines the carrier frequency of the transmi...
Simple AM Transmitter – Circuit Schematic
Simple AM Transmitter
There are not many AM transmitters that are easier to build than this one because the inductor is not tapped and has a single winding. There is no need to wind ...
Shortwave Monitor – Circuit Schematic
Shortwave Monitor
This broadband AM receiver enables you to monitor` the shortwave radio band. The circuit has been deliberately designed to have low selectivity and is most sens...
Medium-Power FM Transmitter – Circuit Schematic
Medium-Power FM Transmitter
The range of this FM transmitter is around 100 meters at 9V DC supply. The circuit comprises three stages. The first stage is a microphone preamplifier built ar...
Opamp VHF FM Transmitter – Circuit Schematic
Opamp VHF FM Transmitter
ICs that in the past were far too expensive for the hobbyist tend to be more favourably priced these days. An example of this is the AD8099 from Analog Devices....
Linear RF Power Meter – Circuit Schematic
Linear RF Power Meter
The National Semiconductor LMV225 is a linear RF power meter IC in an SMD package. It can be used over the frequency range of 450 MHz to 2000 MHz and requires o...
DCF77 Preamplifier – Circuit Schematic
DCF77 Preamplifier
A popular project among microcontroller aficionados is to build a radio-controlled clock. Tiny receiver boards are available, with a pre-adjusted ferrite antenn...
Active Antenna – Circuit Schematic
Active Antenna
Short-wave listeners often are not able to, or allowed to, install a long-wire antenna or other large dimension antenna in or around the home. In such cases, th...
HAM ATS3a digital – Circuit Schematic
HAM ATS3a digital
I have managed to let the stock ATS-3A transceiver transmit nice BPSK31 "cq ok1iak". The firmware of ATS-3A was modified to allow serial line control, which is ...
Tesla coils – Circuit Schematic
Tesla coils
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Meteor Scatter obs with VHF Radio & Computer – Circuit Schematic
Meteor Scatter obs with VHF Radio & Computer
This page contains material related to the technical issues on taking meteor counts thus monitoring the meteor influx using VHF radio receivers. It is not meant...
Frequency Multipliers – Circuit Schematic
Frequency Multipliers
J1 And J2 are a matched pair of J310`s (can also use U310`s or a U431 matched pair). R2 is selected to bias the 2 FETs with a small drain current with no RF inp...
The SDR-1000 – Circuit Schematic
The SDR-1000
Emphasis on the high bands (902 thru 10 GHz) had been a priority here at ARS KMGT for the last few years. The low bands were in pretty good shape, so not much o...
24 Ghz – Circuit Schematic
24 Ghz
The thought of going to 24 GHz was far from my mind back in the summer of 2002. We had just come back from the Central States VHF convention in Madison Wisconsi...
multiPIG+ PLL circuit – Circuit Schematic
multiPIG+ PLL circuit
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RF-AMP Documentation – Circuit Schematic
RF-AMP Documentation
The amplifier can be used in a number of projects to buffer and amplify outputs from devices such as Direct Digital Synthesizer (DDS) chips. The board was initi...
DECUS Documentation – Circuit Schematic
DECUS Documentation
The following describes the design, construction, operation and use of the DECUS divider module. Photo 2 shows a top view of the module and Photo 3 shows the bo...