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 […]

Tutorial, experiments and teardown of a 77GHz automotive FMCW radar module

Tutorial, experiments and teardown of a 77GHz automotive FMCW radar module from The Signal Path: In this episode Shahriar explores the principle operation of automotive FMCW radars. Thanks to a donated automotive radar module, various components of the system can be examined and explored. The PCB reveals three die-on-PCB ASICs responsible for generating and receiving 77GHz […]

Shirt Pocket Transceiver with the Si5351 and OLED

Pete Juliano’s (N6QW) Shirt Pocket Transceiver with the Si5351 and OLED display: In 2011 I fulfilled a dream of building a shirt pocket sized QRP SSB transceiver. Well actually I built two of them and the second was a diminutive 2″ X 4″ X 2″. Both used through hole components –so no cheating with SMD. […]

CTCSS fingerprinting: A method for transmitter identification

Oona Räisänen from Absorptions wrote an article about experimenting with CTCSS fingerprinting: Identifying unknown radio transmitters by their signals is called radio fingerprinting. It is usually based on rise-time signatures, i.e. characteristic differences in how the transmitter frequency fluctuates at carrier power-up. Here, instead, I investigate the fingerprintability of another feature in hand-held FM transceivers, […]

Input filter and preamplifier – Jupiter modular receiver

Vasily Ivanenko blogged about his input and RF preamplifier build: Above — Build of the input and RF preamplifier stage. I put in a 0 or 6 dB attenuator right at the input. That’s double-sided Cu+ board with copper vias joining the 2 surfaces intermittently and also at crucial ground points. Project info at QRP HomeBuilder blog.

Raspberry Pi RF frequency counter

A Raspberry PI RF frequency counter project from Scott Harden, that is available on GitHub: Raspberry PI RF Frequency Counter with Python Interface. The RF signal clocks a 32-bit counter (SN74LV8154) connected to a 16-bit IO expander (MCP23017) accessable to the Raspberry Pi (via I²C) to provide real-time frequency measurements from a python script. More details […]

VHF Frequency Counter with PC Interface

Scott has published a new build: This is the general idea behind how this frequency counter works. It’s so simple! It’s entirely digital, and needs very few passive components. sn74lv8154 is configured in 32-bit mode (by chaining together its two 16-bit counters, see the datasheet for details) and acts as the front-end directly taking in […]

40 meter XCVR size of an business card with 1 watt output, 7.000 to 7.150 MHz coverage

A business card size homebrew 40 meter XCVR project from Ray Ring: I tweaked my previous XCVR design to use push button tuning and made the board layout extremely compact. I improved the side tone injection to be absolutely  perfect – not too loud, full break in and no clicks. I went ahead and integrated my switch […]