After years of oblivion:

The combeback of
satellite radio

The older ones among us surely remember the OV evening discussions in which DX connections via OSCAR-10, were enthusiastically compared. These discussions were held by "SAT specialists" and were very strange for the shortwave amateurs. The technology was incomprehensible to many, or apparently required a high level of "know-how" and extensive financial resources.

Items 1-10 of 17

  1. DXPatrol QO-100 Full Duplex Groundstation
    User report
    DXPatrol QO-100 Full Duplex Groundstation

    Complete unit for the QO-100 Es'hail satellite. 10 GHz receiver, 2.4 GHz transmitter max. 10 W, incl. LNB and GPS antenna, 10 MHz reference.

    In stock, shipped in 1 to 2 days

    incl. VAT, plus shipping €881.51
    SKU QO100-GS-FDX
  2. ELAD Down Converter from 739/430/144 to 144/50 MHz
    ELAD Down Converter from 739/430/144 to 144/50 MHz

    HF down-converter for QO-100 reception with LNB and other applications.

    In stock, shipped in 1 to 2 days

    As low as: €162.00
    incl. VAT, plus shipping €136.13
  3. QO-100 Rx Set with selectable IF
    QO-100 Rx Set with selectable IF

    QO-100 RXSET 2 with selectable IF (10m, 2m, 70cm, 23cm)

    In stock, shipped in 1 to 2 days

    incl. VAT, plus shipping €150.42
    SKU QO100-RXSET2
  4. LNBs for Satellite operations on 10 GHz (QO-100)
    LNBs for Satellite operations on 10 GHz (QO-100)

    LNB for satellite operation on QO-100 or 10 GHz Tropo, Rain Scatter and many more. Always with Bias-T, various equipment versions with or without POTY adapter, with or without 10 MHz reference input, and IF optionally on 432 or 739 MHz.

    In stock, shipped in 1 to 2 days

    As low as: €65.00
    incl. VAT, plus shipping €54.62
  5. DXpatrol QO100 Up-Converter Mk3
    DXpatrol QO100 Up-Converter Mk3

    Allows transmission from a HF, VHF or UHF radio to the QO-100 satellite uplink.

    No longer available

    As low as: €120.00
    incl. VAT, plus shipping €100.84
    In stock
  6. DXpatrol QO-100 Upconverter Mk4
    DXpatrol QO-100 Upconverter Mk4

    Upward mixer (up-converter) for QO-100, IF adjustable 10m, 2m, 70cm or 23cm, output power approx. 200 mW on 2.4 GHz. Highly stable internal 10 MHz oscillator or external reference clock input.

    In stock, shipped in 1 to 2 days

    As low as: €139.00
    incl. VAT, plus shipping €116.81
  7. QO-100 Up Converter 10W
    QO-100 Up Converter 10W

    Localino upconverter for QO-100, IF adjustable 10m, 6m, 2m or 70cm, output power up to 10 W on 2.4 GHz, input power 10 mW to 5 W.

    In stock, shipped in 1 to 2 days

    incl. VAT, plus shipping €293.28
    SKU QO-100-UPCH
  8. QO-100 Rx Set, IF 740 MHz
    QO-100 Rx Set, IF 740 MHz

    Kit of modified LNB plus PLL/Bias-T block, 25 MHz reference clock source, fixed IF 740 MHz.

    In stock, shipped in 1 to 2 days

    incl. VAT, plus shipping €83.19

Items 1-10 of 17



What types of antennas are suitable for satellite communication?
Parabolic antennas or flat antennas are suitable for satellite communication. Parabolic antennas offer high signal gain and are ideal for receiving weak satellite signals. Flat antennas are more compact and lightweight, making them suitable for mobile applications.
What cables and connectors are used in satellite communication?
Coaxial cables and connectors such as SMA or N-type are used in satellite communication. Coaxial cables provide good shielding against interference and signal losses. The choice of connector depends on the specific application and the devices used.
What other accessories are important for satellite communication?
In addition to antennas, cables, and connectors, there are other important accessories for satellite communication. These include LNBs (Low-Noise Block Downconverters), which receive the satellite signal and convert it to a lower frequency band, as well as satellite receivers and transmitters, which are responsible for transmitting and receiving the signals.

OSCAR-10 was a popular amateur radio satellite at that time, which was sent into space in 1983 and with a maximum apogee of 34000km, enabled worldwide radio communications in SSB/CW. The amateur radio market and manufacturers reacted immediately to this satellite and in the CQ-DL SAT-capable full-duplex crossband transceivers ( e.g. FT-726, FT-736... ), as well as satellite antenna systems ( e.g. MASPRO WH-32 ) were offered. Almost as popular as OSCAR-10 were the Russian Radio Sputnik satellites with their 2m/10m or 15m/10m transponders or OSCAR-7 from 1974, which opened up a new world for "C-licensees" and made it possible to establish radio connections as far away as the East Coast of the USA. These satellites orbited the earth at an altitude of up to 1500 km ("Low Earth Orbit", or "LeO" for short) and required rapid operation because the audibility span was often only a few minutes. The highlight of this era was the P3D mission with OSCAR-40. This satellite was sent into space in 2000, but after the first orbit corrections errors occurred and the satellite could only be used on 2.4GHz. By 2004, OSCAR-40 was unusable.

After that, it unfortunately became quieter around the topic of "amateur radio satellites". The satellite section of CQ-DL became smaller from issue to issue. The "Kepler data", with which one could feed one's satellite tracking software, also disappeared. This did not mean, however, that there were no more amateur radio satellites. However, those that were in orbit had apparently become uninteresting to many radio amateurs. The remaining satellites were mostly without linear transponders (SSB/CW operation). In addition, the satellite flight altitude was low and in some cases only a packet radio or FM converter was on board . After a long dormant period until 2019, the launch of OSCAR-100 is creating a real "hype" around the topic of amateur radio satellites. Es'hailSat Qatar Satellite Company made it possible to attach an amateur radio payload to a geostationary television satellite. QO-100, which is at an altitude of about 38800km, opens up a whole new territory for satellite enthusiasts. QO-100 is positioned over central Africa and its footprint covers an area from Antarctica to Brazil, Greenland, Europe, Asia and Indonesia.

QO-100 uses two transponders (narrowband / WIDE band) as payload, which guarantee SSB/CW/Digital (e.g. RTTY, FT8, SSTV ) and DATV radio connections in the mentioned area. In the various specialist forums on the Internet, people speak of a so-called "dedicated amateur radio band", because the transponder bandwidth is an incredible 500 kHz for narrowband operation (SSB/CW/DIGI).

What do you need to become
QRV via QO-100?

The range of options available in the meantime is wide. The transponder of QO-100 works in the so-called SX mode, i.e. it receives in S-band and transmits in X-band. ( 2.4GHz UPLINK / 10GHz DOWNLINK )

The radio amateur, who at the beginning could not yet fall back on ready-made components, was helped by equipment from WLAN and television reception technology. These included WLAN amplifiers, BIAS-T components and commercially available PLL LNBs. In the meantime, the market offers a number of products that make it easier for radio amateurs to set up stations.

Here are some examples: To use the narrowband transponder of the QO-100 satellite, one must find a way to generate an SSB/CW signal on 2.4GHz in the listening range of the transponder. This always requires a clear line of sight to the satellite and sufficient power to bridge the path attenuation! The company DX-Patrol of CT1FFU offers some useful components. These are from converters, power amplifiers, complete stations on "transverter basis" and receiver components. The DX-Patrol UP-Converter MK4 is an inexpensive solution, which turns a VHF or UHF all-mode transceiver into a UPLINK station for 2.4GHz. The UP-Converter can be controlled on 28/144/430/1296MHz, has a HF-VOX and converts to 2.4GHz. The converter power is approx. 200mW and the maximum control power of the transceiver must not exceed 5W. For this UP converter, the manufacturer suggests using a bandpass filter when driving at 28MHz, as harmonics are to be expected. In general, the control frequency should be as high as possible. The less the UP converter has to mix up the frequency! The ideal frequency would be 430MHZ, because this would make an FT-991A, FT-818, IC-705 or IC-7100, for example, a usable control transceiver. To amplify the 200mW of the UP converter, DX-Patrol offers a suitable 12W power amplifier, which includes a 12V/28V voltage converter. This PA works with PTT or VOX and can be connected directly behind the UP converter.

The only thing missing now is a suitable antenna system and a low-loss cable, because on 2.4GHz every dB and every metre of cable length is crucial! A simple and unobtrusive antenna solution for the transmitting branch would be a long HELIX antenna with sufficient gain, as seen here.

By the way, QO-100 expects a clockwise polarisation on the ground station signal. Other polarisations result in corresponding losses. Using longer helix antennas and 12W power results in a well readable SSB signal at the transponder. An additional gain is achieved with so-called WLAN grid antennas. Although you lose 3dB due to the linear polarisation (only vertical or only horizontal), you get a much higher antenna gain. These antennas are inexpensive, have a low wind load and can be easily attached to existing masts. To further amplify the transmitted signal, mirror antennas now come into play. Normal offset Sat mirrors with a diameter of +- 80 cm from television reception technology are suitable. The exciters in the focal point can be so-called POTY feeds, short HELIX antennas or Yagi groups. There is a plethora of examples and solutions on the Internet. Some parameters are important for transmitting via QO-100. The transmitted signal must not exceed the bandwidth of 2.7kHz, the signal strength at the transponder must not be higher than beacon level and you definitely have to watch out for harmonics. This can only be done by listening to your own signal. And that brings us to the reception of the satellite. The easiest and most cost-neutral method is to use WEBSDR receivers on the internet. Be it GoonHilly in England or IS0GRB in Sardinia. With these, well equipped receivers, one can easily listen to the narrowband transponder of QO-100. In the meantime, there are even possibilities to control the transceiver and WebSDR with OmniRig, so that the transceiver automatically adjusts when the frequency changes.

Set up your own receiving system

If you want to set up your own receiving system, you need a system that covers the X-band (10489.5 MHz). DX-Patrol also offers suitable components in the form of a ready-made LNB (which is attached to an offset satellite dish) and a down-converter.

The LNB is supplied with a reference signal from the down-converter, which provides a stable oscillator frequency. Furthermore, the down-converter gives the possibility to mix down the satellite output frequency to an amateur radio band. Thus, it would be possible to receive the downlink frequency with a shortwave receiver, an RSP / AirSpy SDR receiver, an RTL chip dongle or HF/VHF/UHF all-mode equipment. If you prefer to work with a commercially available LNB, you can use a commercially available PLL LNB and possibly equip it with a good TCXO. The output frequency of the LNB is then approx. 739 MHz. A good SDR RX or an RTL chip dongle can also be used as a receiver.

This setup allows you to set up a very inexpensive QO-100 station and gain initial experience with the transponder and satellite technology.

If you want to have it more professional and comfortable, you should have a look at the DX-Patrol ground station components. CT1FFU has developed a plug-n-play setup that allows simplex or even full-duplex operation. In addition, a frequency stabilisation by means of GPSDO, which does not allow any frequency drift. (Without GPS stabilised oscillators, the transmit or receive frequency may drift somewhat. However, the built-in TCXO is quite stable and reacts only slightly to thermal changes.) With the Full-Duplex ground station and a Sat-capable Full-Duplex transceiver, such as the ICOM-9700, you have a very professional QO-100 setup. One can only look forward to the new ICOM IC-905, which is directly capable of transmitting on 2.4GHz! Alternatively, two transceivers can be used to set up a full-duplex station. Often heard on the transponder are stations with two Yaesu FT-817/818 units. Of course, there are a lot of alternatives in the transverter field. Be it Kuhne-Elektronik, Hilberling, the BU-500 from Taiwan, Hartwig-Elektronik or SG-Labs. In any case, one should look around on the market here and decide what fits best. Here is the example of a QO-100 station, consisting of individual components from different manufacturers:
In addition to the converter and transverter solutions mentioned, one naturally finds the SDR systems on the narrowband transponder. The ADALM-Pluto from Analog Devices, LimeSDR or an Hack-RF are pioneers here. The Adalm-Pluto as a full-duplex transceiver with an enormous band spectrum is the top league of signal quality after installation of a stable TCXO and use of appropriate firmware, in conjunction with a good PA and the software SDR-Console. The TRX can be used directly via USB on the computer or via LAN as a remote transceiver near the antenna. To stay with the ADALM Pluto, in conjunction with a much more powerful power amplifier, this transceiver is used for DATV in the wideband transponder range. Corresponding instructions for the Pluto conversion and the appropriate firmware can be found here

The operating technology on QO-100

The band plan of the transponder gives clear rules for the modes to be used. You have to stick to this plan, i.e. CW in the CW range, SSB in its given range. The distance to the PSK beacon or keeping the emergency frequency free must also be observed. The narrowband transponder gives a maximum signal bandwidth of 2.7 kHz. ESSB fans who have modified their transceivers to 4kHz via menu settings will not make friends on the transponder. Likewise, the use of overdriven power amplifiers or extreme voice processor settings do not bring any added value. A call via QO-100 is the typical "CQ satellite". If you are new to the transponder, you will receive a reply very quickly and successfully log DX connections. Since the transponder provides a bandwidth of 500kHz for narrowband operation, rare stations often operate in split mode. Here, SDR receivers with appropriate spectrum display help enormously to work the DX station quickly.

Due to the stable quality and the fact that the satellite is fixed at one point, you don't have to worry about anything else. QSB, interference etc. are unknown here. And not to leave it unmentioned, even contesters get a kick out of QO-100. Because SAT contests in CW/SSB are often offered here. What more could you want!


LeO Satellites ( Low Earth Orbit )

In addition to QO-100, there are of course other alternatives for the interested satellite radio amateur, which should not go unmentioned, because they offer an extremely exciting field of activity. The field of so-called "linear LeO satellites" is worth mentioning, but requires a little more setup and basic knowledge. LeO satellites usually travel at an altitude of between 700km and 1500km. They orbit the earth in a period of about 100 minutes and thus allow several audible passes per day. From orbit to orbit, the audibility range is always shifted and the most diverse regions of the earth can be reached.

The possible distances that can be bridged by these transporters are in part up to the theoretically possible 7800km. The Russian satellite RS-44 or the Japanese FO-29 are real DX satellites. RS-44, which is partly at an altitude of 1500km and has a VU transponder (144MHz up / 435MHz DOWN) on board, offers such DX possibilities. QSOs with the USA, Africa and Asia are almost the order of the day. Likewise Fuji-SAT FO-29, which is currently permanently on, has an almost similarly wide audibility range.

And not to forget, the SAT fossil OSCAR-07, which has come back to life after a long defect, offers interesting DX contacts here. OSCAR-07 does have its quirks, though. In space since 1974, it is only partially usable. The batteries have short-circuited and so the transponder is powered only from the solar panels. This means that the satellite only works when it is in sunlight. In addition, it switches from mode U/V (432MHz UP / 145MHz DOWN) to mode A (145MHz UP / 28MHz DOWN) when the day changes.

Here it is important to obtain up-to-date information from the Internet in order to know exactly which mode is currently active. Appropriate information can be found on the AMSAT status page and other relevant pages dealing with amateur radio satellites. Also highly recommended is the site of N2YO or for predictions under Satmatch, which is indispensable for preparing skeds SATMATCH. Now to other satellites, namely the small CUBEs. China is currently deploying a large number of so-called CUBE satellites ( Small 10cm x10cm satellite ) with amateur radio load in space. The CAS or XW satellite series consists of several linear satellites with a smaller audibility range than the previously mentioned DX satellites. Nevertheless, QSOs have been made as far away as the east coast of Canada. Here is the transponder information from the latest addition, CAS-10.

But, what do you need to become active via this type of satellite?

Also like the QO-100, low-cost and high-tech components are available. First you need to know that the transponders operate on 2 different amateur radio bands. Let's start with the antennas. An Eggbeater set for two bands, turnstyles, a DUO-band Yagi 2m/70cm with horizontal or vertical polarisation; so-called ARROW YAGIS; an antenna set of X-QUADS, a LeO kit or two cross Yagis, would all be possible solutions. Even multiband vertical antennas, such as an X50, X200 could be mentioned here.

Since the Leo satellites rotate around the earth, the distance to the satellite is sometimes very large, sometimes small. In addition, the elevation, the angle of elevation to the satellite, varies during the overflight. Due to the satellite's own rotation, the polarisation of the signal changes in some cases. All this must be taken into account for successful operation via the LeO's and planned for in the setup. An EggBeater antenna is well suited for satellite operation due to its design. Due to the possibility of receiving steeply incident signals well during direct overflights and the flat radiating component next to it, it is a good start. Unfortunately, the gain is not large enough to handle very deep flybys at a great distance from the satellite. This also applies to the vertical antennas, which have to be suitable for steep flybys, as their characteristics are designed for a rather flat radiation angle. This is where Yagi antennas come into play. The DUO-band Yagis known as "Arrow antennas" are ideal for portable operation. They consist of a combination of 3/5 or more elements for 144/430 MHz, are very light and have sufficient gain. The antennas can be tracked by hand and the polarisation can be adjusted as quickly as possible by turning them in case of noise. In the USA, this antenna is very popular in the "Sat Rover community" (stations that activate different large fields). For fixed installations at home, a combination of X-Quad antennas with clockwise circulation is recommended. This combination is very often found among satellite friends. Due to the small size, good performance and a not too narrow aperture angle, a very good setup.

The LeO kit from YU1CF is a perfect system. The large gain and also the possibility of circular polarisation are advantages over normal Yagian antennas, which have possible noise drops during the satellite pass due to the fixed polarisation. In practice, the change between horizontal and vertical polarisation is considerable. With circular polarisation this is only max. 3dB, with linear polarisation considerably more! Nevertheless, even with normal Yagis you will quickly achieve success and DX QSOs are almost the order of the day. Thus, all possibilities are open to the VHF amateur with a 2m 70cm antenna for first attempts!

As you can see in the pictures, most SAT amateurs use mast preamplifiers in the receive branch. If you have a permanent installation at home, it is recommended to use good preamplifiers. For a fixed installation of directional antennas at home, a rotor solution is essential. A horizontal rotor is the minimum, bearing in mind that directional antennas have a defined elevation angle. Thus, for professional satellite operation, an elevation rotor is useful to guarantee a stable signal at higher elevation. At present, SPID ( RAS, RAEL model) and YAESU ( with and without controller) offer such rotors. Ideally, modern rotators can be connected to a PC via an interface and thus be controlled automatically via appropriate SAT tracking software. Such software, be it the well-known Sat-PC32, PST-Rotator or GPredict etc. is a basic requirement. These software solutions not only control the antennas in azimuth and elevation, but also correct the Doppler offset and regulate the transmit/receive frequency of the transceiver(s) via the CAT interface.

Which brings us to the heart of the satellite station. There are enough transceivers for successful LeO satellite operation. However, the flagship transceiver is currently the ICOM IC-9700, which provides sufficient power reserves with 75W on 70cm and 100W on 2m. However, these do not necessarily have to be called up for LeO Sat operation, because here, too, the following applies: "Own signal not louder than the transmitted beacon". Back to the IC-9700, its Sat Mode, its fullduplex crossband capabilities and the control via the USB interface are the measure of all things. Icom has continued the tradition of satellite transceivers. Yaesu, on the other hand, unfortunately did not. With the FT-991A, they also offer a very good transceiver with a 2m and 70cm part. The power of 50W is perfectly sufficient, but the fullduplex mode is missing. You cannot listen back to your own signal on the downlink frequency. This can make operation very complicated! Also missing is a SAT mode, which controls the VFOs in the opposite direction for inverted linear satellites. (Inverted for counter-rotating) An external tracking software must then take over control. Unfortunately discontinued, but still the FT-818 from Yaesu should be mentioned. Despite its low power, it is often used by "LeO friends". Unfortunately, the FT818 does not offer full-duplex or SAT mode. Nevertheless, combinations of a YAESU FT-991A and an FT-818 or an SDRPlay or AirSpy are conceivable, feasible and recommendable. The author uses a combination of FT-DX10 with a 2m transverter for the uplink and an FT-991A for the downlink (reversed in U/V mode).

At the moment, one notices that the demand for old SAT-capable transceivers such as FT-736, IC-820, IC821, IC-910 or TS-2000 is increasing on the relevant Internet sales platforms. The prices offered are accordingly regulated upwards by supply and demand! In some cases, 30-year-old equipment is selling for what it was when it was new.

The operating technology on the LeO satellites

Now to the operating technology. This differs noticeably from the LeO satellites' QO-100 technology. It starts with the operating mode. LSB is used for the uplink, USB for the downlink. This applies to almost all, but only almost all LeO's. Please check the information at SatNogs or AMSAT accordingly! LeO satellites, as orbiting objects, offer the operator only a limited operating time during the orbit. (+- 15min) Once a satellite rises above the horizon, operation is theoretically possible. Provided the antenna has sufficient gain, there are no obstacles (mountains, houses...) between the antenna and the satellite and you can hear the beacon or the first stations! This moment of emergence is called AOS. Within the footprint, all active stations can theoretically be reached from AOS onwards. But all stations have different elevation angles to the satellite, which means that signals from other stations may arrive at the transponder much louder than our signal, because our distance to the satellite is greater at AOS. This also means that we hear less or quieter at the moment. By transmitting immediately with too much power, we could disturb stations. So it is important to listen first, then transmit. And only use as much power as really necessary. At the same time, you should always check the footprint and overflight. Stations with steep overflights and the associated high volume could ruin the chance for others at the edge of the footprint by long QSOs with rare stations. Stations at the edge of the footprint have what is known as LOS when the satellite goes down. (Lost of Signal. Satellite goes below horizon). Therefore, the important rule for LeO operation: "BE SHORT", listen first and live the Ham-Spirit. Give others a chance too! This actually works quite well on the linear satellites. Now for the QSO content: Name, 6Digit locator details, the weather or a setup description are very rarely heard and are also superfluous. Only basic information is of interest! Callsign, report and GRID in the form JO30, JN39 are sufficient. The transponder bandwidths should also be taken into account. You can say that below the transponder centre there is CW operation and above SSB operation. Satellite tracking programmes, such as GPredict, often set the frequency of the transceiver to the middle of the band after starting the programme. This is why the largest number of stations are usually found there. DX stations, on the other hand, often choose the upper edge of the transponder to be able to work undisturbed. If you are an absolute newcomer to the LeO satellites and do not yet use tracking software, you can also perform Doppler correction by skilfully steering the VFOs. To do this, remember to change only the VFO of the higher frequency of the transponder. The lower frequency remains.

An example: RS-44 VU mode:

I transmit on 145965 and change only the downlink frequency in the 70cm band. Please do not change both VFOs. The remote station must also be able to find them! Especially the ROVER stations use this technique of operating without a PC, because who always has his laptop with him in the field?

Therefore, don't be surprised if the remote station is not necessarily "transceive" and drifts away during the QSO, or "whistles in" on the frequency again and again. In summary, LeO operation requires some skill. Azimuth tracking, elevation adjustment, Doppler correction, footprint observation and then rapid QSO operation. Without automation of the antenna and transceiver control, this is a real challenge. The operator should know what he is doing. This knowledge is available to the real DXers on the LeO satellites, who are always trying to break the existing distance records. There, skeds are identified, which have been calculated beforehand via Satmatch possibilities, and driven onto high mountains in order to pull the horizon down. It really takes a lot of preparatory work! But this is what makes the LeO operation so exciting and appealing! And isn't it said that you grow with the challenges?


GREENCUBE a MeO satellite

Last but not least, a new star in the sky, or rather satellite in orbit, is IO-117 ( Italian Oscar 117 GREENCUBE ). This MeO satellite ( Middle Earth Orbit ) rotates at an altitude of 5800km around the Earth. Its amateur radio payload consists of a packet radio transponder on 435.310 MHz in SSB packet mode. Using a 70cm Yagi (min. 10dBi) and 25W, it is possible to make very long-distance radio connections via this satellite. It is possible to reach South America, Japan, North America, Hawaii, Africa and Asia. A fullduplex transceiver is not necessary. Only an SSB capable 70cm transceiver with internal / external sound card modem. Additionally needed is the correction of the Doppler shift by means of a sat-tracking software and packet software. ( UZ7HO software pack ). A Yaesu FT-991A has proven itself here, which enables a sound card and CAT control via USB interface. The 50W output is perfectly sufficient for successful DX operation. Very good instructions for operation and configuration can be found at:


If you exhaust all these possibilities, you can operate worldwide with a "neighbour-friendly antenna system". Diplomas like the WAC, VUCC, DXCC, WAZ and for real experts, the Worked All States, are within the realm of possibility.

As a satellite fan, you use the QSO confirmation via LotW and office. The log entries Sat-Name, SAT, Band, Sat-Mode are extremely important! On the LeO satellites, this type of confirmation has become established. On QO-100 we are clearly lagging behind. So, don't wait long and just try out the satellite mode. The large SAT community is always happy about new large fields, new callsigns and interesting QSOs. When will we hear each other on RS-44 or QO-100?

Important rule