Ham Radio

Here is a collection of articles related to Ham Radio, one of my hobbies. You can find here various build projects but also software applications designed for experiments or radio operations. I posted also some articles on various field activities with my friends.

Harris 300W UHF pallet — how good could this be as a QRO for 70cm amateur radio band ?

Harris 300W UHF Pallet

A couple of days ago I received from a friend of mine a Harris RF power pallet salvaged from a scrapped equipment. This pallet would be able to dissipate apx 300W PEP (black) on a 50 ohm load on ∼800 Mhz. Unfortunately I have no documentation for this. I do have the schematic but is […]

How to use Matlab PCBReader objects

Recently I installed a trial version of the new PCB toolbox from Matlab. From Mathworks website: RF PCB Toolbox provides functions and apps for designing, analyzing, and visualizing high-speed and RF multi-layer printed circuit boards (PCBs). You can design components with parameterized or arbitrary geometry, including distributed passive structures such as traces, bends, and vias. […]

Malamute SDR

I have to confess that I fail to comprehend this obsession for cheap chinese devices. Although I understand the “cheap” part of the rationale, what constantly amaze me is the fact that usually people that buy such stuff are not necessarily financially challenged — a fact that could justify such a choice. Let’s be honest: […]

Cold shrink tubes

I discovered this technology rather recently on YouTube and I was instantly hooked by the opportunities. I bet most of you who had to insulate connectors or sections of hardware (like antenna segments, for example) relied heavily either on self vulcanizing tape or on electrical insulation tape. Both had disadvantages but for me the deal […]

Field Day, Tuzla, 2023

The fourth edition of Tuzla Field Day took place this year on 14-17 September, 2023. Some pictures:

Multipurpose RF Proto Board v2.0

This is a general purpose PCB that I designed in KiCad as a helper board for my Manhattan-style mounted RF projects. It allows connection via SMA connector (vertical or edge mount) and BNC. The two completely separated prototyping sections can be interconnected by using the SMAs in the middle or, if you want to save […]

Motor drivers for antenna rotator

I made some progress on my antenna rotator project and installed the stepper drivers and the Raspberry Pi computer. I bought two drivers from ardushop.ro and these should work just fine. They are based on Toshiba TB6560AHQ, PWM Chopper-Type Bipolar Driver IC for Stepping Motor Control. The datasheet can be downloaded from here. My projects […]

Mini N connector – timelapse in Fusion360

I needed this 3D design for a mini N connector that I have in my shack but I was unable to find any 3d file (.STEP etc) online. The connectors are used for my 101dB attenuator project. Enjoy ! Greetings.

Build SvxLink on Orange Pi — aide-mémoire

This is mostly a memory helper, to remind me some steps in the setup of Svxlink on Orange Pi Load packages sudo apt update sudo apt install g++ cmake make libsigc++-2.0-dev libgsm1-dev libpopt-dev tcl8.5-dev libgcrypt20-dev libspeex-dev libasound2-dev libopus-dev librtlsdr-dev doxygen groff alsa-utils vorbis-tools curl libcurl4-openssl-dev git rtl-sdr libcurl4-openssl-dev Create svxlink user and add to groups […]

Build SvxLink on Raspberry — aide-mémoire

This is not really a post, but mostly a reminder with some information to help me remember the steps. Meanwhile I wrote a much more extensive documentation here, on my wiki (in romanian). And I think I also made a video tutorial but I have to upload it to YouTube. Load packages sudo apt update […]

First steps with Orange Pi

This is rather a reminder, not a real post. This is a collection of links to help me in my quest to control this device.

Tuzla 2020, Field day

I published on my YouTube channel a video about the ham radio Field Day event at Tuzla, Romania, 2020.

KiCad Templates for Orange Pi Zero

KiCad templates for two different hat models for Orange Pi Zero boards can be downloaded from my GitHub repo. Two different KiCad templates can be downloaded in the same GitHub archive: one uncut, 46×48 mm exactly same size as Orange Pi Zero; the other one has some cuts for network and USB connector, to accomodate […]

LTSpice simulation of Baofeng UV5R band selector

I was quite busy the other day trying to understand how Baofeng is using RDA1846 transceiver in their products. While analyzing the schematic it struck me the overcomplicated way they do the switch between UHF and VHF. This is an excerpt of the schematic: The entire selector block is made up with discrete components ! […]

AD8307 RF Power Meter III — build

This will be another short post. I also made the GitHub repo public, but please be aware, current design is flawed. If you use it, you acknowledge that you use it on your own risk. Today I managed to build the revision 1.0 of this power sensor, not without some lessons learned. It was my […]

AD8307 RF Power Meter II — boards from JLPCB

I ordered the boards for this project with JLCPCB in China. This is my first attempt of working with a professional PCB manufacturer and I am extremely pleased by the results.

AD8307 RF Power Meter

My first finished KiCad project is a prototype of a RF Power meter with input attenuation built around an Analog Device AD8307. An excellent tutorial about log amps can be read in March 1999 edition of Analog Dialogue. KiCad PCB: And the 3D rendering of the same PCB: The next step will be PCB ordering, […]

TH-D74 BLE or “Bluetooth Low Energy”

Struggling to understand how Universal Unique IDs work (see here) I was wrongly assuming that Core Bluetooth is a framework from Apple that covers all aspects of communication with devices via BT. I was WRONG ! scanForPeripheralsWithServices method and, in general, what I tried to do, for almost a week, is NOT good for my intended […]

Using UUIDs and Bluetooth

I did some more steps towards accessing Kenwood TH-D74’s services via bluetooth. I struggled for some time understanding how discovery based on UUIDs work. I was not aware that, for each service profile, there is a standard Universally Unique Identifier (UUID) documented in Bluetooth SIG specs. Specifically for Serial Port Profile (SPP) service, the UUID […]

Why unsupported central manager state ?

Several days ago I received a Kenwood TH D74 portable transceiver. Although I have a Yaesu FT60 and some other smaller and unimportant transceivers, I don’t have any transceiver that is APRS capable. What’s more important, this transceiver is BT and USB capable, providing serial communication, which opens some interesting opportunities. Today I opened XCode […]

Kenwood TH-D74

We first met — I think — in the summer of 2015 during the Hamfest in Friedrichshafen. At that time I had a mobile Kenwood transceiver TM-D710 which was quite nice by its own. However, after several months using the TM-D710 I got increasingly annoyed by some of its shortcomings, most of them purely subjective (but I […]

Beacon with SiLabs module

This is a beacon project started by my friend YO5VAE. He faced some issues while programming of the Si4463-based module and I thought I might give a hand. I resoldered the entire project on an empty Arduino shield to allow expansion of the project with some additional modules. Below are some pics, but probably the […]

Năsăud Cup, 2017

There is nothing better than marrying several hobbies and have fun from it. I have had the intention to be part of this expedition at least since I heard about this contest for the first time. My good friends from Năsăud planned this thoroughly. All our equipment was carried by three 4×4, manned by a […]

Ferrite beads

I ordered some ferrite beads for a RF circulator project I currently work on but these might also be very handy for the SWR bridge project. These are extremely efficient for RF supression, or at least this is what they say.

Boards for prototypes

For low frequency projects, a fast way to prototype is using a bare PCB and scratch some dividers that allow “manhattan” style prototyping. I am especially very fond of this prototyping technique and I believe that PCB design should be avoided in the early stages of prototyping. Jim Williams was an artist in such designs. […]

OCXO tests

A couple of months passed since I purchased two 10 MHz OCXO modules from eBay. And, to my shame, I didn’t even tried these. Yesterday I did a quick test and the devices are spot on. Both measured on my TTi TF930 3GHz frequency counter: The OCXO needs apx 10 minutes for proper warm up […]

A visit to a special workshop

My friends from YO5KUC Ham Radio Club embarked on a very ambitious project: they want to participate in the Amateur Radio on the International Space Station (ARISS) program. Now, for those of you that are not familiar with ARISS, this is a awesome educational project run by NASA: “ARISS lets students worldwide experience the excitement of […]