Advertisement
FM/PM Demodulation The Phase Lock Loop – Circuit Schematic
FM/PM Demodulation The Phase Lock Loop
We saw how it is possible to create signals which carry information by modulating the frequency or phase of a carrier wave. Here we`ll examine how it is possibl...
Motorola Mitrek conversion to repeater or link – Circuit Schematic
Motorola Mitrek conversion to repeater or link
This document is written in attempt to include everyone interested in serious construction of a quality product. Its very technical, however, written openly and...
Direct FM – Circuit Schematic
Direct FM
For this project the 1 1/4 meter Midland 13-509 ischosen, mainly because it`s use in several (transparent) links, which support the SRG 147. 20 repeater. First ...
Yaesu FT-736R AGC – Circuit Schematic
Yaesu FT-736R AGC
The FT-736R is a V/UHF all mode transceiver. A picture of the FT736R can be seen in figure 1. This article will show how you can modify the AGC (Automatic Gain ...
LOW COST SOLAR RADIO SPECTROGRAPH – Circuit Schematic
LOW COST SOLAR RADIO SPECTROGRAPH
The analog interface is a very simple analog to digital converter which accepts the analog video output of the RF/IF board and puts it into a form that can be r...
Improved Anode Circuit Parasitic Suppression for Modern Tubes – Circuit Schematic
Improved Anode Circuit Parasitic Suppression for Modern Tubes
This is the unexpurgated, pre-edited version of the article "Improved Anode-Circuit Parasitic-Suppression For Modern Amplifier-Tubes" that appeared on page 36 i...
One transistor FM radio project – Circuit Schematic
One transistor FM radio project
...
Low Tech FM Radios – Circuit Schematic
Low Tech FM Radios
Broadcast band frequency modulation (FM) radio was invented to solve existing problems with noise and fidelity on the amplitude modulation (AM) broadcast band. ...
FM Converters – Circuit Schematic
FM Converters
The FM broadcast band was moved immediately after World War II from its original spot just below 50 Mc to the present 88-108 Mc band. Hallicrafters was one comp...
RF amplifier and filter for 2.5MHz – Circuit Schematic
RF amplifier and filter for 2.5MHz
By use of transformers one can apply both voltage feedback and current feedback. There was an article in Ham Radio november 1979 by DJ2LR Ulrich Rohde giving de...
RF amplifier and filter for 70 MHz – Circuit Schematic
RF amplifier and filter for 70 MHz
The RF amplifier uses noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift b...
RF amplifier and filter for 144 MHz – Circuit Schematic
RF amplifier and filter for 144 MHz
The RF amplifiers use noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift b...
RF amplifier and filter for 10.7 MHz – Circuit Schematic
RF amplifier and filter for 10.7 MHz
The RF amplifier is similar to the one used in the 2. 5MHz amplifier. At a frequency of 10MHz the capacitances of a power MOS-FET become significant. Noiseless ...
2 VALVE TRANSMITTER – Circuit Schematic
2 VALVE TRANSMITTER
This transmitter is very stable and will deliver up to seven watts of power with the components and tubes shown. Do not be put-off by valves as they are VERY ea...
DIRECTION FINDING SYSTEM – Circuit Schematic
DIRECTION FINDING SYSTEM
If you have the time and money then make this plate bigger, if possible. 5-meters would be ideal for a home base. Similar to the system used in modern aviation ...
DIODE-SWITCHED SYNTHESISER – Circuit Schematic
DIODE-SWITCHED SYNTHESISER
My particular favourite was the MC145152-2 that could be programmed with DIP switches, a diode matrix, or even a pair of EPROM look-up tables. But sadly, those ...
Amplitude Modulator with OTA – Circuit Schematic
Amplitude Modulator with OTA
Circuit described in the schematic diagram below can achieve 99% modulation easily with maximum frequency of 200kHz. The amplification of this circuit can be.....
Small Broadcast-Band AM Transmitter – Circuit Schematic
Small Broadcast-Band AM Transmitter
This AM radio circuit is a low power transmitter working on broadcast band. The simplicity is implemented using a single-transistor amplifier stage, and for.....
50 kHz FM Optical Receiver – Circuit Schematic
50 kHz FM Optical Receiver
Frequency modulation (FM) can be used to transmit analog voltage level signal with good noise immunity. The transmission itself  might employs different.....
UHF Doppler Motion Detector – Circuit Schematic
UHF Doppler Motion Detector
The UHF motion detector below operates on the Doppler radar principle. A radial signal is created by the oscillator (Q1). Some of this energy is reflected back....