W8USR - Station Equipment
Astron RS-70M Heavy-Duty Linear Power Supply
Technical Specifications
The Astron RS-70M is a high-capacity, linear regulated DC power supply engineered specifically for demanding commercial communication terminals and heavy-duty amateur radio installations. Built around a substantial internal transformer footprint, this power plant provides an exceptionally quiet, RF-silent power envelope across the HF/VHF/UHF bands. Key technical parameters include:
| Engineering Property | Manufacturer Technical Specification Value |
|---|---|
| Primary Output Voltage | 13.8V DC ± 0.05 Volts (Internally adjustable from 11V to 15V) |
| Current Capacity (Continuous) | 57 Amps (Continuous Duty cycle profile) |
| Current Capacity (Surge/ICS) | 70 Amps (Intermittent Commercial and Amateur Service peak load) |
| Input Line Voltage | 105–125V AC, 60 Hz Single-Phase AC Allocation |
| Ripple Voltage Profiles | Less than 5 mV Peak-to-Peak (At full capacity rated load and low line inputs) |
| Overall System Efficiency | 77% Power Conversion Performance Ratio |
| Thermal Range Parameters | Operational capability maintained from -10°C up to 55°C |
| Integrated System Safeguards | Fold-back current limiting, automatic crowbar over-voltage protection, and chassis AC fuse |
| Telemetry Monitoring | Dual backlit integrated LED instrumentation meters (Real-Time Volt / Amp) |
| Cooling Infrastructure | Heavy-duty external chassis cooling fins with integrated thermal fan array |
| DC Output Hardware Links | Dual 1/4"-20 threaded screw terminals sitting on the rear enclosure wall |
| Physical Footprint Dimensions | 6" High x 13.75" Wide x 11" Deep |
| Net Equipment Weight | 50.0 Pounds (Linear transformer mass ballast) |
Radio History & Station Integration
Station W8USR acquired the Astron RS-70M power supply in 2019 to accommodate the integration of the Icom IC-7300 HF transceiver into our primary desk layout. The introduction of this heavy-duty power plant allowed the bench to completely phase out two legacy Astron 35-Amp power supplies, consolidating our current generation distribution rails into a single, high-capacity electrical core that easily handles our full operating workload. The companion IC-7300 rig represents a major milestone in amateur hardware design, popularizing professional-grade RF Direct Sampling technology within a highly accessible, all-in-one format. Featuring a high-resolution color touchscreen interface, an intuitive real-time spectrum scope, and an internal sound card modem, it is uniquely optimized for high-duty cycle modes that require clean, unregulated DC stability.
Station Role & Operating Footprints
The Astron RS-70M serves as the foundational backbone for the entire W8USR radio station, supplying uniform, low-ripple 12-volt DC rails across the main operating console while the IC-7300 remains the central core for our high-frequency voice operations. During live station actions, the transceiver tracks alongside an Apple MacBook Pro computer running the MacLoggerDX terminal suite created by DogPark Software. Utilizing Computer Aided Tuning (CAT) links, this digital interface enables our computer and radio to communicate directly, permitting remote macro command execution over frequency arrays, volume parameters, and rapid band changes.
This stable power platform allows us to actively explore advanced on-air communication methods. We track a diverse mix of historical and cutting-edge signal fields, including:
- FT8: Currently the single most popular digital mode in amateur radio worldwide, utilizing structured, time-synced structural tones to decode weak signals far below the noise floor.
- FT4: A highly optimized, rapid variant of FT8 specifically designed for faster pacing during contest windows.
- PSK31: Phase Shift Keying at 31 baud, offering a conversational keyboard-to-keyboard layout with a narrow bandwidth footprint.
- RTTY: Radioteletype, supporting traditional automated data-exchange nets across the shortwave bands.
- DMR: Digital Mobile Radio, linking local repeating infrastructure directly into global internet-linked talk groups.
Originally, the station roadmap included adding a solid-state power amplifier in the 500 to 1,000-watt class to boost our HF output. However, thorough research revealed that this upgrade would require a domino effect of expensive infrastructure updates. For instance, our current manual antenna tuner—the MFJ-969—is strictly rated for a maximum capacity of 300 watts. Stepping up to a high-power legal-limit deck would require installing an advanced automatic system like the MFJ-998 1,500-watt automatic antenna tuner, which features automatic memory tracks across 1.8 to 30 MHz alongside analog cross-needle telemetry links. Furthermore, driving an external amplifier alongside the transceiver would heavily stress the current draw capabilities of a single power supply. Consequently, the amplifier expansion project has been abandoned, and the Astron RS-70M remains the perfect, highly stable power core that easily and reliably manages every device on the desk.