An experimental HF 6-band SSB transceiver

Peter (DK7IH) has been working on HF 6-band SSB transceiver: Part 1: Project Basic Outline Presentation Part 2: The Oscillators (VFO, LO and Testtone Osc.) Part 3: The Microcontroller (ATMega128) Part 4: Bandswitching Logical Circuits Part 5: Measuring Transceiver Data Part 6: The Receiver Part 7: The Transmitter Part 8: Transmit/Receive Switch Unit Part 9: […]

FIREO – a low power SSB/CW tranceiver with its unique speech processing

Kang.K.P.S. writes: “FIREO” (Pronounced FIRE-O), is basically a bit of non-conventional QRP (low power) SSB/CW transceiver design in which speech compression is implemented using FM limiter circuit. This unique approach of speech processing increases the effective average transmitted power and thus it improves on the signal strength reports at the receiving end. Consequently this technique […]

“Cigarette Pack”- 14MHz SSB QRP Micro-Transceiver

Peter Rachow (DK7IH) built a 14MHz SSB QRP Micro-transceiver into a cigarette packet size case: This article describes the “Cigarette Pack” SSB QRP transceiver” for 14MHz that I first had mentioned some months before. Recently, when taking it from the shelf, the transceiver dropped to the floor and was severely damaged. This lead to serious […]

A transmit converter (and amplifier) for 630 and 2200 meters

KA7OEI has a great write-up on building a transmit converter for 630 and 2200 meters: As the name implies, a transmit converter takes another frequency – such as that produced by a conventional HF transceiver – and converts it to another frequency.  In my case I use an FT-817 – a low-power (5 watt) all-mode, […]

A simple 8-channel receiver voting controller for enhanced repeater coverage and usability

KA7OEI has written an article detailing a simple 8-channel receiver voting controller: To simplify things, this voting controller sits in “front” of an ordinary repeater controller, taking the audio and COS inputs from the various receivers and outputting a single audio and COS signal. If the repeater system in question uses subaudible tones, it is […]

Automated channel switching with Motorola GM3x0

Florian Wolters wrote an article on automated channel switching for POCSAG/DAPNET transmissions on MMDVM system: With the integration of POCSAG/DAPNET features into the MMDVM/MMDVMHost I came to think about if it would be possible to combine an MMDVM repeater/HotSpot with a DAPNET tranmitter. The advantage in Germany is that there is a single coordinated frequency […]

A limited attenuation high-pass filter for the KiwiSDR

KA7OEI published a new build: One of the issues common with using a broad-band, direct-sampling SDR (software-defined radio) like the KiwiSDR is that of overload by strong, low-frequency signals, such as those on the AM (mediumwave) broadcast band – but there’s another problem that should be considered as well:  The high generally-high signal levels at […]

Tutorial: Setting up a low cost QRP (FT8, JT9, WSPR etc) monitoring station with an RTL-SDR v3 and Raspberry pi 3

A detailed tutorial on how to set up a cheap QRP monitoring station using an RTL-SDR V3 and a Raspberry Pi 3 from rtl-sdr.com This tutorial is inspired by dg0opk’s videos and blog post on monitoring QRP with single board computers. We’ll show you how to set up a super cheap QRP monitoring station using an […]

Transistor radio series: the AF power amp

Vasily Ivanenko @ QRPHB writes, “I sought a low distortion, single supply, AF power amplifier for my transistor radios. I’ll present my experiments, some musings, test equipment and a reference to some wonderful books & their wise author. Sadly, some amateur radio receiver builders diligently craft their RF stages, but skimp on the PA audio stage. […]

Transistor radio series – The 7 MHz scratch synthesizer

Vasily Ivanenko has written up documentation on his 7 MHz synthesizer project: Above — All 4 boards were built in re-purposed Hammond boxes. A PIC-based counter sits on top of the offset mixer. I build modular gear and this allows modification and fosters experimentation. When I build a final transistor radio receiver, I plan to […]

Simpleceiver Plus version 2 SSB transceiver

An update on Pete Juliano’s (N6QW) Simpleceiver project we covered previously: Version 2 — What is it? V2.0 is the Simpleceiver Plus SSB Transceiver Architecture with the following changes: A GRQP Club 9.0 MHz Crystal Filter is used in place of the homebrew 12.096 Four Pole Filter. This gives the advantage of acquiring the matching […]

A two channel SI5351 signal generator

DuWayne Schmidlkofer has a nice write-up on building a two channel SI5351 signal generator: After getting the sketches written for the SI5351 board written to support multiple display types, I decided I need to write one more. Now that Pete is moving the Simpleceiver to a single conversion super-het, I will have to worry about […]

Teardown and repair of an Agilent 53152A 46GHz microwave frequency counter

Agilent 53152A 46GHz frequency counter teardown and repair from The Signal Path: In this episode Shahriar investigates a faulty Agilent 53152A 46GHz frequency counter. The instrument does not power on and shows no sign of internal voltage presence. Teardown of the instrument reveals a large PCB where all analog and digital circuity is contained. The power supply […]