Reflections about a remote mediumwave listeners station

The DT 770 replaces Sennheiser's HD 465. @home I'm still using the old Staxx Flat membrane headphone.

Left: The terminating resistor of currently 820 ohms is waterproof in an HT tube. The connections are mounted on lamp terminals, without much effort to remove.

Center: Middle: The mast top in 7.50 meters, to the left of K9AY mast. An aluminum tube of 4 m length carries the tip, attached to the plum tree with clamps, freestanding.

Right: The 9:1 balun also resides in an HT pipe. The 4m long mast made of aluminum stands with only 2 guy wires in a ground pipe, which once served as a prop for a parasol. I still wrap my balune myself ...

For the 40 m long wire I use galvanized uninsulated electric fence wire with a diameter of 1mm. Source: 1000 m / < 33 €

Shot 1: Flag-Loop. The noise level is near -138 dBm, signal at -105.3 dBm. Direction 80°.
Shot 2: K9AY. The noise level is near -130 dBm, signal at -107.1 dBm. Direction 35°.
Shot 3: 50 m longwire. The noise level is near -127 dBm, signal at -108.5 dBm. Direction 30°. Connected two CMCC.

It looks a bit better than I suspected in the last post. The antennas were for comparison without preamplifier.

Note: A precise statement can not be derived from this, all antennas should have had the same direction.

The loop has a total circumference of almost 40 m and closes the gap between northeast and southeast of K9AY. The top of the mast is 7.50 m high. The direction of reception is 80° across the northern Indian subcontinent, via Southeast Asia, western Australia and the New Zealand South Island, huge targets for MW-DX.

The loop can be relocated with a few simple steps, if necessary. For Central America reception, only balun and resistance are reversed. As it is rather quiet without a suitable preamplifier, it is amplified by the RPA-2 from DX-Engineering. This brings 17 dBm, which is still 10 dBm below the noise figure of the the K9AY or the 50-longwire.

The flag loop was built according to the pattern of FO0AAA, but is twice as large. The audible front-to-back ratio is better than K9 and longwire, as is the directivity. It was the only antenna that audibly filtered Palangkaraya, Indonesia at 3325 kHz (31.9.2019, 17z).

So much wood for an antenna that is suspended relatively quickly. Some preliminary work is nevertheless necessary for the measurements to be correct.

More additions to the loop will bring time. Now I'm curious.

It should be more correct, the system was not running anymore, so it was changed.

The disaster with the Trekstor tablet since November has now come to an end. Even after the second inspection of the device - shortly after it came back from the 1st - at Trekstor no error could be found. My subsequent in-house inspection revealed that the battery is no longer providing enough power to power the SDR and WiFi adapters. Unfortunately, the battery is excluded from the warranty, permanently installed and obviously not available as a spare part. Even an external current hub is no longer useful.

The device is still functional and useful for other purposes, but unsuitable for the remote station. The dream of a functioning station based on low power consumption has to be redesigned. The solar-powered 12 V DX system needs a new heart.

About the progress of my efforts to build a small but nice station in the garden, I will continue to report when I have found and tested appropriate devices.

Maybe I'll get new ideas and suggestions at Ham Radio.

Until then, the break screen remains here.

I wish all of you reading this a great time - and maybe you'll see each other in Friedrichshafen!

73, Willi

A new solar panel creates more energy, and a thankful discovery. During the installation of the 50 Wp panel, I discovered an unclean line connection at the 1st 100 Wp solar panel. It was the reason for more than a year accepted but insufficient charging situation. With the 2nd panel and the now clean wire, the current strength of about 0.7 A could be increased to an adequate 3.0+ A. In full sunshine this is a quadruple of the energy supply. The charging time of the batteries will be shortened by a few days. In addition, a large 4.7 Ah notebook can be operated almost lossless during the day.

The new panel in the middle of the picture, on the left a 15 Wp panel for a pond pump. Both panels are connected in parallel.

Also new is a 47 Ah car battery, which can serve as a reserve for the two 100 Ah liquid / gel batteries.

That was quite a piece of work until the refurbished station was allowed to present itself as in this picture. The new heart of the station, a 7-port USB 2.0 hub with 12V / 5V seperate output, reliably controls the current flow to the ELAD FDM-S2. A new linearly regulated 5-V power supply ensures in the background that this works smoothly. The Trekstor Tablet still hangs on a conventional 5-V power supply without any RF interference detected so far. I used the opportunity to lay cables and devices even better than before. A downer remains: SDR-Console V.3 can not be persuaded to timed automatic recordings. It never stops with the station work. But first I'm happy that everything is up and running again - time for DX!

Due to problems with the tablet I decided to start the built of a air-sun-collector. The device replaces the woodburner inside. The pole in the middle is part of the 45 m horizontal loop.