The information listed here is the Recommended hardware for an ISS Amateur Radio School schedules. The MAREX-MG team has run over 80 school schedules since 1991 with the Russian Mir Space Station. Most of the school schedules were success stories. Some of the failures were directly related to school amateur radio systems designed with Low gain antenna systems (Omni style verticals, Turn-Style, etc). It is very important to have the proper antenna gain and an overall efficient antenna system to improve your chances of success and for maximum schedule duration. The information below was written specifically for the schedules with the Mir space station. This information is also valid for radio links with the International Space Station Alpha.

• Transceiver: Yeasu 736R
• Antenna: KLM-CP22 or M2-22, 40 Element CP antenna for 70cm
• Coax: LMR600SF, RG-213 or Flexible-9914
• Amplifier with Pre-Amp: RF-Concepts or TE Systems 150-170 watts output
• Expected System ERP: Greater than 1600 watts
• Rotor System: Kenpro/Yeasu 5400 AZ/EL
• Computer Controlled Antenna: Optional, strongly recommended

• Any All mode 2-meter station, Yeasu 736R, ICOM 820, Kenwood TS-790
• Antenna: Omni directional or better
• Coax: RG-213 or Flexible-9914
• Amplifier with Pre-Amp: Optional
• Expected System ERP: Greater than 50 watts
• Rotor System: Optional
• Computer Control: Optional

The Yeasu-736R transceiver is the only Amateur radio on the market with both a Triple Conversion FM Receiver and built in Wide & Narrow FM filters. The Triple Conversion FM Receiver gives you excellent receiver sensitivity and selectivity. The Narrow Band FM filters will help prevent intermodulation problems and reduce adjacent channel interference. This feature is very important in a city environment where there is a stronger possibility of interference. This radio is also equipped with a FM tuning meter. This meter can be used to help you fine tune the receiver and know when to adjust transmit channels to optimum performance. If you cannot get access to a Yeasu-736, there are other similar all mode 2-meter/ 70cm stations, which could be used, ICOM 820, Kenwood TS-790

The antennas on the Mir Space Station and the International space stations are both linear polarized 0-dBd-gain verticals. Because of the apparent rotation of the Space Station, there will be 4 antenna polarity shifts. These shifts will cause deep signal fades because of a cross polarization situation. A Circular Polarized antenna at the school is mandatory to help reduce the amount of the signal fades. The common high gain linear polarized will suffer from polarity shift problems and signal fades. It is highly recommended to you only use a high gain circular polarized antenna for your primary station.

Beware of published antenna gain figures. Most manufactures will play games with the antenna gain values and try to deceive you into believing the antenna has more gain than it really does. Look closely at the way the gain value is written. The correct way to write a gain number is:

dBd or dBc or dBic

dBd Antenna compared to a Half-wave Dipole (the most realistic value).

dBc Antenna compared to a Half-wave Circular polarized Dipole

dBic A theoretical Half-wave Circular polarized Dipole in free space

Most sales material will used the deceptive dB value.

dB Undefined reference, invented by salesmen for the purpose of deception.

Most Yagi antennas with a published dBd or dBc will be fairly accurate Gain numbers. However 99% of all Omni directional antennas will have bogus antenna gain figures. As a general rule of thumb, always subtract 3 from the published values for Omni antennas.

Example: Cushcraft Ringo Range II ARX2B

Published gain 7.0 dB (note the letters dB)

More realistic gain 3-4 dBd

The Mir and ISS Space Stations are traveling around the Earth at over 17,500-mph (28,000 kph). This great speed will make radio signals appear to shift in frequency. This phoneme is called Doppler Shift. To compensate, you will use the "Clairifyer" control to fine-tune the receiver.

The Doppler shift will cause the Mir transmit frequency (145.895) to look as if it is 3.5 kHz higher in frequency when Mir is approaching your location. Get out your manual for your radio and look up the section on "Odd-Splits" and program in the following consecutive frequencies into your radios' memories.

Channel 1 145.987.0 TX 145.983.0 RX

Channel 2 145.985.0 TX 145.985.0 RX

Channel 3 145.983.0 TX 145.987.0 RX

If your school is chosen for an actual MAREX schedule, you will be issued additional frequencies to program into your radio. Program in all channels issued to your school, including the public listed above. Make sure you also program all of the required channels into your backup radio. And suggest you keep the channel numbers on both radios the same.

When Mir is approaching your QTH, use channel #1. Then when Mir is over head, use channel #2. When Mir passes your QTH use channel #3.

You should also use the "Clairifyer" for the finer adjustments to the receiver.

Do not use a VFO to tune the Transmitter!

Keep watching the FM tuning meter on the receiver. The Doppler shift is not linear. As Mir gets closer to your QTH, the rate of frequency change will speed up and then slow down.

For best results, use an updated tracking program, which displays the current Doppler shift. A program such as InstaTrack will display the Doppler shifts in real-time. This program will assist you in determining when it is best time to change channels.

The Doppler shift is only at the +3.5 kHz setting for a few seconds, then it will begin to approach zero. After 5 minutes or less, the Doppler shift will be 0 for a few seconds, then it will begin to swing towards -3.5 kHz.

The Doppler shift is much high on 70 cm.

The Doppler shift will cause the Mir transmit frequency (437.950) to look as if it is 10.0 kHz higher in frequency when Mir is approaching your location. Get out your manual for your radio and look up the section on "Odd-Splits" and program in the following consecutive frequencies into your radios' memories. (Sample frequency, the exact school frequency will be assigned to each school)

If your school is chosen for an actual MAREX schedule, you will be issued additional frequencies to program into your radio. Program in all channels issued to your school, including the public listed above. Make sure you also program all of the required channels into your backup radio. And suggest you keep the channel numbers on both radios the same.

When Mir is approaching your QTH, use channel #1-4. Then when Mir is over head, use channel #6. When Mir passes your QTH use channel #7-11.

You may also use the "Clairifyer" for the finer adjustments to the receiver.

Do not use a VFO to tune the Transmitter!

Keep watching the FM tuning meter on the receiver. The Doppler shift is not linear. As Mir gets closer to your QTH, the rate of frequency change will speed up and then slow down.

For best results, use an updated tracking program, which displays the current Doppler shift. A program such as InstaTrack will display the Doppler shifts in real-time. This program will assist you in determining when it is best time to change channels.

The Doppler shift is only at the +10.0 kHz setting for a few seconds, then it will begin to approach zero. After 5 minutes or less, the Doppler shift will be 0 for a few seconds, then it will begin to swing towards -10.0 kHz. The Doppler shift is not Linear, the greatest amount of drift takes place near the half way mark during your schedule.

For temporary setups I do not recommend solid center conductor 9913. The 9913 type of cable is prone to Kinks and water leakages, which can cause sever SWR problems. You will have fewer problems if you stay with flexible solid foam coax cable types such as RG-213 or similar coax cable. Try to keep your coax runs fewer than 100 feet if possible. (During a Shuttle schedule in NH, I was called to come down to the school and bring my whole radio station because the schools station had failed because the new coax was full of water).

The 2-meter band uses two incompatible coax connectors, the SO-239 female, PL-259 Male (formally called UHF connector) and the "N" connector male/female. Most Satellite beams used the N connectors, and the radios accept PL-259 connectors. Make sure you have the correct connectors on the ends of your cables and plenty of extra PL-259 to N connector's adapters.

The power output from the transmitter should match the Amplifiers input ratting. The Yeasu generates approximately 25-27 watts on 2-meters. The RF Concepts (model number) is designed to accept a 25-30 watts input and generates 150-170 watts output. You should strive to design you station for a similar match. We have had problems with Amplifiers being over driven and burning out during school schedules.

Maximum Power:

For safety reason, we do not recommend using power levels greater than 200 watts. A 150-watt station with 14-dbic gain and typical coax losses will be generating over 1600 watts of ERP. This power lever will be sufficient to capture the Mir radio in most situations.

Pre-Amplifiers work best when placed at the antenna. However this is not always practical and sometimes it becomes very difficult to adjust SWR with an additional Pre-Amplifier in line. It is recommended that you use an amplifier mounted Pre-Amplifier, located next to the primary transmitter. The performance of the amplifier mounted Pre-Amplifier is a little lower than an antenna mounted pre-amp, but you will have fewer logistic problems when you use a Pre-amp which is built into the RF-amplifier. Also, sometimes you may experience more interference problems when the Pre-amp is turned ON. Be ready to hit the Pre-amp OFF switch in case you receiver becomes overloaded. If your station is located in an area with lots of RF traffic you may also want to consider installing a DCI 2-meter pass band filter to assist in blocking QRM from outside of the 2-meter band. (DCI filters work good)

There are several Azimuth Elevation rotor systems available on the current market. Most systems are acceptable. The Azimuth accuracy reading must be within 10 degrees of true North. The Elevation accuracy reading must be within 10 degrees of zero elevation.

Computer antenna control is optional but highly recommended. The 5400 rotor system will interface with the KCT computer controller. A computer controlled antenna system will make it easier to you to track the satellites orbit. The KCT System will allow you to enter antenna alignenmets corrections into the software to compensate for antenna pointing errors.

All rotors can only turn approximately 360 degrees. There will be a stop built into the rotor, which the rotor cannot go past. This stop will either be at North or South, the antenna cannot go past the Stop point. If your Stop is set for North, and the orbit of the satellite is NW to NE, then you will hit the stop point half way through your schedule. It takes most rotors 60 seconds to spin all the way around to the other side of North. The orbit of the Satellite will either be North or South of your school.

When your school is assigned a time slot, run the STSPLUS tracking program to display the orbit path. This will help you determine where to set the rotor stop. You will want to try to avoid hitting the Stop during your schedule. However, you assigned time slot may change and you will need to be able to compensate by switching to a backup Omni antenna or the backup radio, until you are able to realign the directional antenna system.

There are several main items responsible for the correct aiming of your antenna system, at the fast moving satellite. They are, Location (latitude & Longitude), Time clock, Tracking Program Keperarian data and Antenna installation pointing error.

The location (Latitude and Longitude) of the transmitting antenna need to be known so the data can be entered into your satellite Tracking program and this data also needs to be sent to group organization the event. Using an off the shelf Topographical map you should be able to locate your antenna position with an accuracy of less than 1000 feet. If you have access to a GPS receiver, you will be able to find the antenna location down to less than 300 feet. The 1000-foot radius will be sufficient for our needs.

The computers being used to track the satellite and control the antenna will need to have the clocks set to the correct time. There are several computer programs on the market, which can automatically dial by telephone and automatically load the correct time into your PC (InstaTrack, Nova GPS at http://www.webcom.com/w9ip/ )). You can also load the time the old fashion way, by listening to WWV broadcasts and setting your digital watches. Try to get the time error in your computers to less than 2 seconds of error.

The SAREX or MAREX-MG group will be able to provide the school with current tracking data called Keperlairan Elements. This data is generated every 2-3 days. One the day of the schedule, you should try to load in data with a Satellite time stamp of less than three days old (Epoch time: 96274.83271966, this is the year 1996, 274 day etc.). However usually week old kep data is sufficient. Typical tracking errors with 7-day-old keps are less than 10 seconds. There are exceptions: once every 6-8 weeks the Mir Space Station will perform an Orbit-Burn. This maneuver may cause the schools schedule time to shift by several minutes. Orbit-Burns are usually not pre announced and we only find out about the Orbit-Burns 2-3 days after they take place.

Aligning the antenna with True North (not magnetic north) is one of the harder things to accomplish. It is difficult to get pointing error to less than 10 degrees. The antennas beam width will help compensate for the pointing error.

The elevation of the antenna should also have an error of less than 10 degrees.

Typical example of Total Errors for Azimuth (Worst case)

Timing errors

Time clock 2 seconds

Tracking program 5 seconds

Subtotal 7 seconds

Antenna Installation 10 degrees

Timing Error 2 degrees

Subtotal 12 degrees

The beam-width of the typical 22-element CP antenna is 28-30 degrees. Which means, you can miss the target by one half of the antenna beam-width without noticing any signal drop. If we assume our antenna has a BW of 30 degrees, we can then miss the target by 15 degrees and still receiver the maximum signal.

If our total worst case error is 12 degrees and the antenna Bandwidth is 15 degrees, we still have a 3-degree or a 9-second aiming buffer. Yes this is rocket science, but it is fun. If you want to attempt to improve your antenna aiming, try making adjustments to the easiest parts first, the computer time clock and current Kepelarian Elements.

Contact the site electrician to help you locate two separate circuits for the radio equipment. Lets assume you have two 20 amp circuits available in the classroom. Here is a typical configuration:

Circuit #1 Circuit #2

Transceiver PC for Tracking

Power supply for Amplifier Backup Radio Station

Power for Rotor

PC, If rotor is computer controlled.

What happens if you pop a circuit breaker. Proper planning will help you avoid that problem. Try to avoid letting people plug in their camcorders and stuff like that into your power source. Bring plenty of power cords and power strip to support all of your equipment.

What time of the year are you having this radio schedule?

How many people are you expecting to be in the radio room?

I was at one schedule for STS-71, in Hudson Mass, on July 3rd. We stuffed over 500 people into a school cafeteria on a hot summer's day. There was no air-conditioning. It was very unpleasant. But the smiles on the children’s faces during the successful school made it worth the heat and effort.

WF1F MAREX-MG

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