Tonight I heard again after a long time the Letter Beacon (MX) "K" on 7039.3 kHz. This beacon is located in he Russian Far East, possibly near Petropavlovsk-Kamchatsky according to the IARU Region 1 Monistoring System and the HF underground wiki. While other beacons of this cluster moved out of the 40 m amateur radio band to 7509 kHz, this one remained on its old frequency.
Today I received a Radiometrix NTX2-434.650-10 LPD transmitter module which I ordered on eBay from mallinson-electrical. I integrated it with an Arduino Uno, a female SMA socket and a 3λ/4 antenna to build a small RTTY beacon. Output power is about 10 mW, consistent with the LPD specification CEPT/ERC Recommendation 70-03.
I programmed the Arduino with a modified version of M0UPU arduino code, which is published on the site of UKHAS.
|Reception of the LPD beacon using fl-digi|
I hope some time within the next weeks to make a test transmission from a high location so anybody interested can get some hands-on experience with dl-fldigi reception of balloon signals.
The interesting news is that Radiometrix produces a new version of the transmitter, called NTX2B-FA, which is frequency programmable, so it can be tuned to more appropriate amateur radio frequencies near 432.8 MHz.