Some quick measurements on a DK2DB balun.
My first experiences with this board on 20m using a FT82-44 core are, that the core gets hot at 5W on 20m / 14MHz.
Based on this experience I consulted the mini Ringkernrechner and and did some calculations. As far as I understand, the primary coil with 3 turns limits the maximum usable power.
I've developed a small interface board for the HAMWARe controller AT-502, AT-515 and AT-651B. This interface boards supports RS232 and CI-V communications and can be directly mounted into the controller chassis.
Browsing the internet, I stumbled over an interesting video on YouTube were a guy shows a very cheap ESP32+camera solution to read the analog readout of water meters.
I started my journey into QO-100 with a very simple setup. Details can be found here. The previous setup consists of the well known LimeSDR-mini, a pre-amp and a modified WiFi-amp. No I placed all the components into an old case - not so fancy but sturdy.
I started my journey into QO-100 with a very simple setup. Details can be found here. I used purely SDRConsole to receive & transmit audio via a simple USB headset. This was no real comfort and it was not capable transmitting CW ;-)
Fortunateley Andreas DL4JAL published 2021 in the German ham radio magazin FUNKAMATEUR an interesting hardware console. The basic idea behind this console is, that through the internal soundcard SSB-audio as well CW-audio can be transmitted. A hardware PTT key can used to switch SDRConsole into transmit mode. Furthermore it controls the timing for T/R-switching - SDRConsole has some delay between audio input and rf-output via the LimeSDR-mini - so no loss of last DIT or syllable.
This post deals with the first one - the QRPGuys Portable Tri-Band Vertical Antenna:
Some days ago I setup a simle RTL-SDR based monitoring station. Now after about 5 days of more or less constant monitoring I found one interesting thing:
I stumpled across this intersting post on RTL-SDR.COM talking about monitoring TirePressureMeasurementSystems with a cheap SDR stick and a clever piece of software. The rtl_433 software receives and decodes signals transmitted by tire pressure sensors inside the wheels of modern (I assume at least from the last 10 years) cars.
My initial idea is, that I can monitor the traffic in front of my house - at least traffic of modern cars. As Germany is a car centric country, I expect to catch most of the traffic.
As you can see in this post, I've used a simple slide switch to control the power for the sensor keyer. This was a little bit annoying, as you must always check, whether you've turned of the power, when you leave the shack.
As power consumption is not really a big issue - the keyer draws about 2.5mA from two AA-cells. Based on the capacity of an average Energizer Classic AA battery of 1.200mA you will get an on-time of about 300h.
Since many months I've had the idea, to add an electronic switch to the keyer, so it switch of automatically after 15 minutes of idle time.
Die Orignal-Firmware des Steuergeräts des HAMWARE Tuners AT-502 hat eine Funktion eingebaut, welche an Hand eines gesendeten Trägers versucht die aktuelle Arbeitsfrequenz zu ermitteln und den dazu passenden Speicher auszuwählen.
Dies funktioniert bei CW relativ gut, im SSB Betrieb ist dieses Verfahren nicht optimal. Der größte Nachteil meiner Ansicht nach ist aber, dass man zuerst einer Träger senden muss, damit die Frequenz eingestellt wird.