What to expect
Honest expectations for the first month.
Gear tiers
| Tier | Setup | Gets you |
|---|---|---|
| 0 | Any scanner or HT, rubber duck | Hear the ISS and SO-50 on high passes. Decode ISS SSTV from recorded audio. |
| 1 | Dual-band HT + handheld yagi (Arrow, Elk), 5 W | Contacts on every FM satellite. This is where most people start and many stay. |
| 2 | Full-duplex all-mode rig (IC-9700, or two rigs) + computer Doppler control + small yagis | Linear transponders: RS-44, AO-7, JO-97. Long, relaxed SSB contacts. |
| 3 | Add az/el rotator, preamps, sound-card modem | IO-117 digipeating across oceans, weak satellites, unattended telemetry. |
Passes per day
- A LEO satellite gives you 4–6 passes a day. Half are low (under 20°) and marginal. Expect 1–2 good ones per satellite per day.
- Higher orbit means longer passes and more of them: RS-44 (1,175 km) is up 15–25 min, ISS (420 km) 6–10 min.
- Passes cluster: usually two passes about 95 min apart, then a gap of 10–12 hours.
- An overhead pass is not the best pass. 40–70° peak gives good signals without frantic antenna and tuning work.
Doppler
Max shift ±9.5 kHz. Rising: tune 436.8045 MHz. Setting: 436.7855 MHz.
LEO satellites approach at up to ~7 km/s along the line of sight, near zero at closest approach. Try 145.900 vs 436.795: 70 cm shifts three times as much as 2 m.
- FM on 70 cm: step the downlink in 5 kHz steps, +10 → +5 → 0 → −5 → −10 kHz. Five HT memories do it.
- FM on 2 m: ±3 kHz, mostly inside the receiver passband. Leave it alone.
- Linear transponders: let software track Doppler on both radios. Manual tuning of SSB is possible but miserable.
- Inverting transponders: tune your uplink down as the downlink drifts up. Software handles this.
FM repeater reality
- It is one channel. On a weekend pass over a populated area, 20 stations want it.
- Full duplex (hearing the downlink while you transmit) is the single biggest upgrade. Without it you cannot tell if you got in.
- Say your callsign and grid once. Wait. A reply comes or it does not. Do not call CQ repeatedly.
- If you hear nothing, the usual causes: wrong CTCSS tone, antenna polarization, forgot to correct Doppler, or the repeater is off.
Linear transponder reality
- Find yourself first: transmit a short CW or SSB tone and tune the downlink until you hear it. Then call.
- Never louder than the beacon. Excess uplink power drops everyone else's signal.
- Contacts are relaxed. Name, grid, signal report, maybe a chat. Nobody is fighting for the channel.
- Convention: LSB on the uplink, USB on the downlink for inverting transponders.
First-pass checklist
- Pick SO-50 or the ISS. Confirm on AMSAT status that it was heard today.
- Choose a pass with peak elevation above 30°, in a spot with an open horizon in that direction.
- Program the downlink in 5 kHz steps and the uplink with the tone.
- Arrive 5 minutes early. Note AOS azimuth. Point there.
- Listen first. Twist the antenna for best signal. Transmit only when you hear the downlink clearly.
- Log the time, callsigns, and grids. Then report to AMSAT status.