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Archive for the ‘RF’ Category

Practical RF filter design

Monday, March 20th, 2017

[embed]http://www.youtube.com/watch?v=1sq8Cvju2Oo[/embed] Craig writes, "RF filter design is a piece of cake these days thanks to computer design and simulation tools. But actually realizing the simulated filter response in the real world can be a completely different matter! This video provides an introduction to practical RF filter design by building, testing,...

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Shirt Pocket Transceiver with the Si5351 and OLED

Monday, January 16th, 2017

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...

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Forty-9er Shield

Friday, December 23rd, 2016

m0xpd writes: I've been tinkering with a quick lash-up of Wayne Burdick, n6kr's famous 'Forty-9er' receiver, implemented on an Arduino shield and tuned by one of my DDS systems. Regular readers will remember how I tried running my Kanga / m0xpd Sudden-inspired receiver shield under the control of the new...

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Posted in digital radio data, RF | No Comments »

CTCSS fingerprinting: A method for transmitter identification

Friday, December 9th, 2016

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...

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Scalar Network Analyser Jr

Tuesday, December 6th, 2016

M0xpd documented his experience building DuWayne's Scalar Network Analyzer Jr: DuWayne's baby uses an AD9850 in one of our familiar modules to generate RF, under the control of an Arduino NANO. You can read on DuWayne's blog how the SNA Jr is the descendant of earlier experiments in which an Si5351...

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Input filter and preamplifier – Jupiter modular receiver

Tuesday, October 18th, 2016

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....

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Raspberry Pi RF frequency counter

Tuesday, October 11th, 2016

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...

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Posted in R-Pi, RF | 3 Comments »

VHF Frequency Counter with PC Interface

Wednesday, September 7th, 2016

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...

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Breadboard line driver module

Tuesday, August 23rd, 2016

Scott from SWHarden has published a new build: Line driver chips are one of my go-tos for quickly amplifying digital signals because they’re so fast to drop in a breadboard and they provide a strong output with very high impedance inputs and need no external components. Individual buffer of the...

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

Friday, July 29th, 2016

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...

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Progress on the LDMOS amplifier

Friday, July 29th, 2016

An update on Pete's (N6QW) LDMOS amplifier project we covered previously: The real value of the breadboard test system is that it enables you to find/discover things that were not so obvious. Currently I have the Start & Stop buttons wired to the Arduino. I also have all six of...

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Posted in DIY, RF | 1 Comment »

AD9834 and the IoT beacon

Tuesday, July 19th, 2016

m0xpd writes: I've been playing with a new RF generator for the IoT beacon... Actually, I do myself a disservice, because I've done rather more than just play with the RF generator. First, I've replaced the little USB to serial dongle which I used to program the original system and built...

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Georges F6DFZ’s very stylish homebrew version of the Scout Regen receiver

Tuesday, July 5th, 2016

Dave Richards AA7EE has published an article about Georges F6DFZ’s homebrew regen receiver: Several months ago, Georges F6DFZ sent me pictures of a Manhattan project he had just completed, using Rex’s MeSQUARES, and I have waited far too long to share it with you. It began life as a copy of the...

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LDMOS amplifiers

Friday, June 24th, 2016

Pete (N6QW) writes: This project encompasses proving an Arduino Control of a hi Power Linear Amplifier. It is a new departure for N6QW as it has extensive I/O requirements which required moving to the Mega 2560 a Arduino variant that has 56 Digital I/O and 16 Analog Inputs. The on...

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Tracker for thing, APRS tracker with DRA818V

Friday, June 3rd, 2016

Tony G from Weird-Lab writes, "The idea of this project was to build a trackuino board with small gps module, low power arduino pro mini (3.3v @8mhz), a VHF transceiver DRA818V, and power management integrated." Project info at Weird-Lab site.

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Crystal motional parameters

Thursday, May 19th, 2016

[embed]http://www.youtube.com/watch?v=y-rCgumTn4Q[/embed] Craig writes: Ever tried searching through your datasheets for the motional parameters of that quartz crystal you just bought? Good luck! Vendors simply don’t specify these parameters to general end users, and for most applications that’s OK. But for high Q oscillator and filter design, measuring and matching crystals...

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Posted in how-to, RF | No Comments »

Simple crystal tester

Monday, May 2nd, 2016

Dilshan Jayakody writes: This is simple Colpitts oscillator to test commonly available passive crystals which range between 2MHz to 27MHz. This unit must connect to an oscilloscope and/or frequency counter to get the frequency of the crystal. This circuit is design to work around 9V to 12V DC power source....

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Building a better RTL-SDR TCXO

Tuesday, March 22nd, 2016

Craig posted an article describing how he built a 28.8MHz RTL-SDR TCXO, that is available on github: Here’s a scratch-built 28.8MHz TCXO capable of +-1ppm stability from 0C-55C; best of all, it’s not only easy to build, but is designed entirely from readily available and inexpensive components. For improved temperature...

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14 GHz Ku Band Block UpConverter

Thursday, December 3rd, 2015

Sebastian (a.k.a KF5OBS) writes,  "A quick look at what it takes to make a Block UpConverter (BUC) for the 14 GHz Ku-Band satellite uplink band work. A BUC is used in professional Broadcast TV environments to convert a video signal from a L-Band intermediate frequency to the 14 GHz range...

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The Sproutie “SPT” Beacon – A legal, unlicensed HiFER beacon

Thursday, November 19th, 2015

Dave Richards (a.k.a. AA7EE) has written an article detailing his "SPT" Sproutie HiFer beacon project: My first “proof of concept” at putting together a beacon for this band was to connect an N0XAS PicoKeyer in beacon mode to my Pixie 2 transmitter. With the PiicoKeyer, if you insert the prosign BN...

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Recent Comments

  • Edward Mallon: I've managed to get cheap thermistors calibrated to about to +/- 0.2C with 3.3v Arduinos. https://edwardmallon.wordpress.com/2017/04/26/calibrating-oversampled-thermistors-with-an-arduino/ Instead of playing whack-a-mole with the various sources of...
  • Ja: What the keyer do? Sends random morse code or there is some input? If someone can point me to some source to read I would...
  • Sorin: Pleasure of free!
  • hli: Sunday++
  • Max: Jolly good stuff, although the "include 100 W resistors in series with the inputs and outputs" part is quite hilarious until one realizes* they meant...