Author: ms

GNI-r5 controller for RAU, RAK, BIG-RAK and RAEL rotators

Rotary antenna rotator controller. A new model of the GNI-r5 antenna rotator controller is available. Compared to previous versions, it has new features and a new steel casing. The following is the shorted operating manual for the GNI-r5 antenna rotor controller.           Introduction. The GNI-r5 controller supports one rotor with pulse […]

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 […]

Electret microphone instead of dynamic and vice versa

Some transceivers have a microphone input adapted to the electret microphone and some to a dynamic one. It is not possible to replace them due to design differences. The electret microphone contains a FET transistor in the capsule, which must be supplied with DC voltage in the same wire as the audio signal. The FT-991 […]

The Great Orchestra of Christams Charity transmits from the stratosphere

Colleagues associated in SP6ZWR and SP5MASR to celebrate the 27th edition of the Great Orchestra of Christmas Charity released amateur radio balloons with SSTV, RTTY and APRS transmitters for the 2 m and 70 cm bands. Using the FT-991, the MA-1300 omni-directional antenna and the MMSSTV program, I managed to pick up several pictures. The […]

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 of receiver quality. 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 […]


September 14, 2018 Marek SP5ISZ announced that he had started up QRP from the island of Milos. He had an ICOM 703 (10W only) with a 7.5 Ah battery, an LW 41m antenna about 6m above the ground, about 50m from the sea on the beach. With a 9: 1 transformer, the antenna has tuned […]

HF5L Radio Club in SSB Fieldday 2018

After a successful escapade on the CW part of the Fieldday competition in June, we organized another trip to take part in the phone part of the contest on September 1-2. This time there was no rain or storm, the weather was for 59! There were many operators willing to work on the SSB: Andrzej […]