Category: Category: Designs

DX from space

Amateur telemetry reception from ARTSAT2 interplanet probes: DESPATCH and Shin-en2. Authors: Piotr SP5ULN, Michał SQ5KTM, Piotr SP5MG, Łukasz SQ5RWU. Introduction Bands above 50MHz are often treated only as local FM communication channels. Here and there in the radioamateur environment, the opinion is repeated that in this frequency domain nothing particularly interesting is happening, excluding only […]

Polish student satellite PW-SAT2 transmits

We live in interesting times. In orbit is the Polish student satellite PW-SAT2 which broadcasts data in our radio-amateur band of 70cm. The history of the PW-SAT2 project is also described in Wikipedia and on the website of the Student Astronautical Circle. There is also an interesting photo gallery from the implementation of the PW-SAT2 […]

QCX transceiver QRP CW

I have been interested in QRP solutions for a long time. Of course, I do not avoid QRO, which like QRP gives me pleasure. Long time ago I built TRX Libra on the 80-meter range, unfortunately I did not have the desire to fully run it. Now I have found a very interesting and modern […]

CHA-250B antenna by SP5GNI

Based on the best experiences found on the web, I made my own copy of the CHA-250B antenna. This antenna has many controversial opinions. I decided to do it because having a Hex-beam directional antenna and SDR radio – I needed a multi-band antenna with omnidirectional characteristics. In addition to the characteristics, the most important […]

How to measure the performance of the HF receiver?

In the comment to “HF5L Radio Club in SSB Fieldday 2018” Marek SP5IXS rightly pointed out that “third order dynamic range is a key parameter”. He also asked good questions: What is the difference between IP3 and “3rd order dynamic range”? What is the relationship between RX sensitivity and “3rd order dynamic range”? As for […]

Rotator Controller Interface for YAESU G-800DXA, G-1000DXA, G-2800DXA, G-5500

Updated: 2018-08-31. The USB-232B interface allows connection of the YAESU rotator controllers to a PC via the USB port. The interface supports various types of YAESU rotator controllers: G-800DXA, G-1000DXA, G-2800DXA and G-5500. The interface works with many HAM logging programs, for example N1MM, DXLab, HRDRotator, HRDSatTrack, also allowing satellite tracking, using the improved RC5-3 […]

Wireless and automatic antenna switching

Automatic antenna switching – good. Wireless antenna switching – even better. But automatic and wireless antenna switching is just that! As I did for the FT-991, it shows the circuit diagram below. The controller is connected to the TUN/LIN socket and is supplied from it (warning! ABCD signals encoding the band are available on the […]

Power over coaxial cable

If a DC power supply is needed near the antennas, the use of a coaxial cable for this purpose avoids pulling the additional cable to the roof or mast. The diagram below shows the DC power inserter – Power over Coaxial (PoC) solution tested by SP5GNI. Coupling capacitors should allow the transfer of relatively high […]

Automatic antenna switching in Yaesu transceivers

Automatic antenna switching is not only convenience, but also safer operation of the equipment. Yeasu transceivers are equipped with a socket on which BCD signals represent the currently selected band. The truth table for the TUN/LIN connector in FT-991 is below: D (pin 7) C (pin 6) B (pin 5) A (pin 4) Dec value […]

More about the rotating antenna by SP5GNI

The article “GNI-r3 rotor antenna rotor controller” describes my simplest structure. The user’s manual is available here. I also mention the extended version – the manual is also available. In fact, I have checked other concepts of rotor control. My first idea was to control the rotor completely wirelessly. Impossible? And yet. After all, the […]