spectrum circuit

Z-Match Antenna Tuner project - This Z-Match is a link coupled all-band tuner. Two all band tank circuits cover 3-14mhz and 14-30mhz. The tank output links are selected with a very heavy duty SPDT rotary switch.

Variacs - Variable Autotransformer - Use these Variac auto transformers for specific application requirements that include, but are not limited to, home coffee roasting, tube amps, and more.

A long wave receiving system - A long wave receiving system using FFT software Spectrum Lab

A PC as VLF receiver - Using a PC with soundcard as a VLF receiver, how to use your PC as a receiver for narrow-band signals in the VLF radio spectrum by DL4YHF

SB-220 Repairs and Modifications - Heathkit SB 220 mods, replacing the Zener ZD1, replacing the plate-voltage voltage divider, adding a keying circuit for solid state transceivers

Receive VLF natural radio with Spectrum Lab - Using Spectrum Lab for the reception of VLF natural radio

60 W Linear Amplifier Circuit  ^updated - The 60 Watt linear amplifier is simple all solid state circuit using power mosfet IRF840.

A NiCAD Battery Charger - A NiCAD Battery Charger with Current and Voltage Limiting

About Cavity Filters - Cavity filters are tipically circuitry behind a duplexer that allow only certain frequencies to pass

RF Sampler - This circuit will let you look at the signal and frequency output of your transceiver.

600v Power Supply - A 600 volts power supply for QRO

Ofcom PLT - Ofcom and Power Line Telecommunications (PLT)

Circuit Improvements for the TS-440S - Some improvements for the Kenwood TS-440S, including distortion level in SSB in transmitted signals, Lack of crispness in the RX audio and Limited transmit frequency coverage.

Icom CI-V Interface - Build this CI-V interface and the additional circuitry to provide PTT from RTS.

Spectrum Analyzer Tutorial and Basics - A summary or tutorial about the basics of the spectrum analyzer, what it is and what it is used for.

Grip Dip Oscillator - Originally eveloped by I1FLC, uses seven plug in coils covering 3.0 to 30Mhz in a Colpitts oscillator circuit.

Build a Test Meter - This article include a circuit that allows a cheap 0-1mA meter to be used as a micro-ammeter or a milli-voltmeter

Make your own multimeter - Homebrew a multimeter with this article

RF Probe circuit - This RF probe circuit allows RF to be measured in the presence of DC

RF Probe for HF - A RF Probe circuit for the RADIO frequency experimenter to check the presence of a RF signal and also to measure its strength

RF Probs and Watt meter - This RF probe can be used at High Frequency (HF) or Ultra High Frequency (UHF) on both 50 and 75 ohm coaxial cables.

A DIY Square Wave Signal Generator - This circuit is very simple and has a fantastic range of potential uses.

ZL2PD HF RF Signal Generator - This circuit came out of some work done for two antenna analysers

Digital HF Antenna Analyser Project - This antenna analyzer measures complex impedance over the 1.6 - 33 MHz HF spectrum by ZL2PD

Analog HF Antenna Analyser - A simple antenna analyser for the HF spectrum with a built-in signal generator with 3-digit LED frequency display.