The setup for operating via the QO-100 satellite has changed slightly. The new version of SDR Console 3.0.7 introduces an automatic frequency offset correction feature. It works by selecting a beacon signal in a separate window and using it to correct the deviation of all signals on the downlink. For example, if a beacon signal shifts 100 Hz higher, the other signals will shift accordingly.
SDR Console on an Acer Aspire One and SDR Newgen USB Receiver
I tested this system on an Acer Aspire One, which I use for amateur radio. However, it is equipped with only a single-core Atom n270 processor and 1 GB of RAM, so reception suffers from dropouts and the program occasionally crashes. In principle, though, it seems that the system for locking onto the beacon frequency works correctly—it just requires a more powerful PC.
SDR Console with the frequency offset correction system enabled
The procedure for enabling automatic frequency offset is:
- enable the display of frequencies above 9 GHz
- add a 9750 MHz downconverter in the receiver settings
- After turning on reception, activate the "Geostationary Beacon" module
- Enable beacon tracking using the first icon with a circle
- mark the beacon signal on the spectrum display (you can use +/- to refine the window)
- Enable synchronization using the triangle icon
I’ve found it helpful to set the SDR Console’s waterfall dynamic range so that even weak signals are visible (the slider on the left in the screenshot) and to set the filter range to 150 Hz to 2550 Hz (2.4 kHz). A filter set to a lower frequency sounds more dynamic, but produces significantly more noise.
SDR Console screenshot: spectrum analyzer, waterfall, and filter settings
However, SDR Console 3.0.7 works well; reception seems slightly better than when using HDSDR.
MRF21045 – 2.2 GHz UMTS amplifier for re-tuning to 13 cm for QO-100
The second change I’m planning is the use of a power amplifier (PA). I managed to purchase a UMTS SSPA with an MRF21045. It is designed for 2.2 GHz, which requires retuning. DB8TF described this on the AMSAT-DL forum, and I consulted with him further regarding the details. The modification involves both input and output matching. Don’t be misled by the picture; the module’s dimensions are 70 x 40 millimeters. The module is therefore very small. However, the amplifier’s efficiency isn’t very high, hovering around only 25%. The supply voltage is 24V.
SP2JYR sold these amplifiers through eBay and Allegro. Available information confirms that an output power of 15W can be achieved with an input power of 0.5W.
Kenwood TM-455e
The Kenwood TM-455E is at the beginning of the transmission chain. It is a high-quality transceiver for the 70 cm band. The signal is routed through a 5-meter coaxial cable to the transverter.
Teroz Power Splitter
The photo shows the power splitter for the LNB. It is a Teroz splitter, which is used in TV systems. The antennas are located on the balcony. The lower offset dish with the LNB is for reception; the upper PW-24 Wi-Fi antenna is for transmission. The SG Labs transverter is currently “hanging” from a cable, which is, of course, only a temporary solution.
Quite a few stations on QO-100 use a helix radiator. This allows them to achieve circular RHCP polarization, which offers a 3 dB advantage over linear polarization—equivalent to double the transmitter power. On the 13-cm band, this is not insignificant. Dual-band patch radiators are also quite popular because they allow the use of a single parabolic dish.
Currently, I have about 50 QSOs, including DX contacts such as ZS6TW and HS0AJ. HS0AJ is very active and easy to work. The number of Slovak stations is also gradually increasing. Why don’t you give it a try, too?