QO-100 Satellite Station

Amateur radio communication via a geostationary satellite

SATGeneral info
Official satellite name: Es'hail-2. The radio amateurs (AMSAT) designated it Qatar Oscar 100 (QO-100).
Satellite built by Mitsubishi Electric Corporation. Weight: 5300 kg
Launched: 15-November-2018 by SpaceX from Kennedy Space Center, Florida, USA.
Amateur radio service was opened on 14-February-2019.

Orbit: Geostationary. Es'hail-2 orbits 35,786 km above the Earth's surface at Equator, and it follows the Earth's rotation. The satellite appears to stand still in the sky. My uplink- and downlink antennas are pointed towards the satellite, and they are mounted permanently (no rotator). The distance from my house in Holstebro, Denmark to Es'hail-2 is 39,171 km.

Transponders: NarrowBand (500 kHz bandwidth), and WideBand (8 MHz bandwidth).
Web-SDR for NB transponder: https://eshail.batc.org.uk/nb/
Web-SDR for WB transponder: https://eshail.batc.org.uk/wb/
More info: https://amsat-dl.org/eshail-2-amsat-phase-4-a


10 GHz downlink:

 
receive chain
Receive chain for QO-100.

Receive chain
The signal from the satellite's narrowband transponder is received on 10.489 GHz. This signal is mixed with the local oscillator (9.75 GHz) in the LNB, and the IF frequency is 739 MHz. The IF is forwarded to the SDR dongle where it is decoded and displayed. The Bias-T supplies power to the LNB while being transparent to RF.

Triax parabolic dish and LNB

Triax offset dish with LNB.

Satellite dish
My dish is a Triax TD78 offset dish; it is 70 cm wide and 78 cm high. It is monted on the wall of my house 2 m above ground. Gain is 37 dBi at 11.7 GHz, and the beam width is 2.6 degrees.

LNB
The LNB is Maximum ST-11 single-port LNB. I bought it in a home improvement store (Harald Nyborg). The LO at 9.75 GHz is phase locked to a 25 MHz crystal oscillator inside the LNB. The frequency is reasonable stable after 30 minutes warm-up.   

Improved LNB
The standard LNB worked, but the frequency drift got annoying. I replaced the single-port LNB with a dual-port LNB. One port is used for the satellite signal and the other port is used for injecting a GPS-controlled clock signal. See the article Rockstable LNB with GPSDO.   

Cable
Standard 75 ohm double-screened cable for satellite TV.
Bias-T
Bias-T.
Bias-T
I found the Bias-T on ebay.com. It supplies 12 V 100 mA to the LNB via the coax cable, and keeps 12 V away from the SDR.  
SDR dongle
SDR dongle.

SDR 
The receiver is an SDR dongle from rtl-sdr.com. It is tuned to 739 MHz (NB transponder). The SDR software on the computer is SDR sharp (SDR#).
HP desktop PC
Desktop PC.
Computer
Desktop PC running Windows 10 (64 bit).
CPU is Quad-core i5-2400 at 3.1 GHz.
RAM is 4 Gb.

2.4 GHz uplink:

TX chain

 Transmit chain for QO-100. 

Transmit chain

Yaesu FT-847 puts out 3 W on 432 MHz. The transverter converts the signal to 2400 MHz at 2 W. The attenuator reduces the signal with 6 dB not to overload the PA. The PA amplifies the signal to 20 W PEP, which is sufficient for all modes including SSB. The signal is radiated towards the satellite by a helix antenna (RHCP). 

If only the transverter is used (no PA), the output power at 2400 MHz will be 2 W. This power level can be used for CW and digimode.

picture Yaesu FT-847
Yaesu FT-847 transceiver.

Transceiver 

My VHF/UHF transceiver Yaesu FT-847 is used for transmitting on 432 MHz. The PSU is a Kenwood PS-30. 

13 cm transverter SG-Lab

13 cm transverter.

13 cm transverter
My 13 cm transverter is made by SG Laboratory Ltd in Bulgaria. The model is TR2300 ver. 1.5. It was delivered assembled and tested from the factory. 

I choose this transverter because:

  • Recommended by other radio amateurs
  • Requires 13,8 V DC at 1 A
  • 2 W output at 2400 MHz 
  • Programmable LO
  • 432 MHz IF
13 cm PA
13 cm PA.

13 cm PA
My 13 cm PA is made by SG Laboratory Ltd. The model is AMP2400. It was delivered assembled and tested from the factory. 

I choose this PA because:

  • Recommended by other radio amateurs
  • Requires 28 V DC at 1.5 A
  • 500 mW input
  • 20 W output at 2400 MHz
21-turns helix for 2400 MHz
13 cm helix antenna.		13 cm antenna
I'm using a 21-turns helix antenna for the uplink. The product name is Helix-13 and I purchased it 10 years ago at wimo.com. The antenna gain is about 14 dB. Wave polarization is RHCP (Right Hand Circular Polarization). The antenna is pointed directly at the satellite in the sky.
Circuit diagram, 13 cm upconverter
The 13 cm upconverter (click to enlarge).

Upconverter diagram
The circuit diagram of the upconverter is shown to the left. The upconverter is built into a metal box.

M1 measures DC voltage and DC current. Based on the consumed current, one can estimate the RF output.   

IC1 converts 28 V DC to 12 V DC.

LED1 is on: 28 V is present.

LED2 is on: PTT is active. The PTT line is controlled by the transceiver.
 front, upconverter 13 cm
13 cm upconverter - front view.

Upconverter, picture 1
rear view, 13 cm upconverter
13 cm upconverter - rear view.		Upconverter, picture 2

Written by OZ1BXM Lars Petersen 24-April-2019. Revised 02-Jan-2021.

Home