Modification of the RF input filter in TEF6686 module

TEF6686 based radio tuners are very popular nowadays. There are two versions of the 10-pin modules.

  • Current version, which is available on Aliexpress (left)
  • Old design for TEA685X, which is pin compatible with TEF668X (right)

The main difference between them is a different RF input circuit. Both designs use balun FM antenna application, but only the old version implements RF filtering.

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Dell Optiplex 3000 Thin Client – Home Server

Recently Dell Optiplex 3000 Thin Client has become widely available on the second-hand market at affordable prices. As compared to the previous generation of low-power terminals (like my previous Dell Wyse 5070 Extended), it has an improved performance and decreased idle power consumption. It features a passively cooled Jasper Lake Pentium N6005 CPU (4 cores, up to 3.3 GHz) and supports DDR4 RAM. Built-in eMMC disk can be used for storage or an optional NVMe SSD installed in the M.2 2230 slot.

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Dell Wyse 5070 – Home Server

Recently I have upgraded my home server to Dell Wyse 5070 Extended. This is a very interesting low power computer in a small form factor. My unit came with Pentium J5005 CPU, 8 GB DDR4 RAM (2 × 4 GB), an Radeon E9173 PCIe graphics card and a M.2 SATA SSD drive. The case is really nice, but the Windows sticker is not. There are many ports around, but I’m not going to use most of them anyway.

My previous setup based on Celeron J1900, 16 GB RAM and Intel 730 SSD has been working fine for 7 years with many services, including FMDX.pl website. I decided to build a new Linux home server, which could also be sufficient for such a long time, while still keeping the power consumption at a low level.

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Raspberry PI 4: PoE with LM2596

During last Black Friday I bought Raspberry PI 4 on Aliexpress for just $36. After initial tests I’ve found out that a good cooling case is definitely a must have. The SoC quickly reaches 80°C under a full load and then throttles from 1.5 to 1.0 GHz per ARM core to maintain the temperature limit, so I ordered a very nice Chinese aluminum case. I love PoE devices – my new toy must also support Power over Ethernet – and it does!

I took a cheap LM2596 DC converter and installed it together with the board in the aluminium case.

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5 GHz Wi-Fi DX record – Denmark logged in Poland @ 745 km

A remarkable tropospheric ducting occurred on August 11 and 12, 2020 between Poland, Sweden and Denmark. The propagation forecasts, which use color hue to scale their intensity, featured red shades over the Baltic Sea. Such a propagation strength is very rare, if ever seen on a forecast for this area. I was looking forward for something extraordinary, especially on the microwave bands. My stationary Wi-Fi DXing setup has been damaged three months ago. I could not miss such an opening, so a DX-pedition was the only option. In the evening of August 11 I made an opportunistic decision to visit the Dylewska Góra in north-eastern Poland. A few hours later, I was standing there with an antenna inside a lookout tower. 

With its tip at 312 m ASL, Dylewska Góra (Dylewska Mountain) near Ostróda is the highest hill of the whole north-eastern Poland. There is a wooden lookout tower atop which provides fantastic unobstructed views between 175° to 340° azimuth with optical visibility up to around 50 km. The driving distance from my location is 135 km and I arrived there in two hours, in the middle of the night (2 AM). I knew that place as I have visited it already once with my friend. Back then in the 2018 we encountered a typical morning inversion without any notable long-range ducting (see the report: Early morning on Dylewska Góra).

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New Year 2020: Excellent inversion over Poland

Ten wpis jest dostępny także w języku polskim: Nowy Rok 2020: Rekordowa inwersja nad Polską

This year’s winter in Poland has been very mild so far and it does not resemble this season in our country at all. In fact, it is more like late autumn with possible light frosts. The forecasts for January are still in line with current weather, so this month will be definitely warmer than average. Starting from the end of December 2019, subsequent high pressure systems began to move to Poland. Such weather favors good propagation conditions, which can significantly increase the range of radio emissions. An inversion in the troposphere can enhance the reception within a wide frequency range, starting from the lower VHF (typically 50-70 MHz), through broadcast radio, television, microwaves and finally even… optical waves.

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Nowy Rok 2020: Rekordowa inwersja nad Polską

This post is also available in English language: New Year 2020: Excellent inversion over Poland

Tegoroczna zima wcale nie przypomina tej pory roku w naszym kraju. W rzeczywistości nadal trwa późna jesień z możliwymi słabymi przymrozkami. Obecne prognozy nie pozostawiają złudzeń i w większości styczeń ma być bardzo łagodny. Od końcówki grudnia 2019 roku z zachodu zaczęły nadciągać nad Polskę kolejne wyże. Taka pogoda sprzyja podwyższonej propagacji, która potrafi w znaczny sposób zwiększyć zasięg emisji radiowych. Inwersja w troposferze może wpływać na odbiór w szerokim zakresie częstotliwości, zaczynając od dolnego UKF-u (typowo 50-70 MHz), przez pasma radiowe, telewizyjne, mikrofale, a nawet… widmo optyczne.

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