Analog HotSpot - Transceiver VHF - UHF 500mW PI4/PI5 CE

Analog HotSpot - Transceiver - 4th Generation

The Analog Transceiver/Hotspot is now in its 4th generation, featuring a redesigned power stage, improved filtering, and a more robust enclosure. We added additional DC-line filtering to eliminate noise sources, improved the thermal design with a durable plastic base and precision-machined aluminium top, added an even more capable internal thermal solution to the Pi 4 and Pi 5 editions, and increased the output power of both the UHF and VHF versions to 28 dBm (~500 mW). The included NoTenna2 attenuates the output to an EIRP of roughly 50 mW by absorbing most of the RF energy. If you need more range, you can simply connect an external antenna.

It is a compact and robust analog communications hotspot built around a Raspberry Pi. Choose the Raspberry Pi 4 edition (1 GB RAM) or the Raspberry Pi 5 edition (1 GB RAM), then select either the UHF 70 cm version (400–480 MHz) or the VHF 2 m version (134–174 MHz). Thanks to its Wolfson WM8960 DAC/ADC, it runs flawlessly as an EchoLink / SVXLink analog hotspot.
* Currently only an SVXLink Bookworm image is available for SVXLink and EchoLink.

Specs at a Glance

Included with the Product

• Complete tested device in a hybrid enclosure with a durable plastic base and precision-machined aluminium top
• Preloaded SD card with our latest image
• A 2 W terminated indoor antenna (50 Ω)
• Free Bluetooth companion app for Windows, macOS, Linux, Android, iPhone, and iPad

Key Features

• ENIG-finished PCB (Electroless Nickel Immersion Gold)
• Independent TX/RX frequencies, CTCSS, CDCSS
• Adjustable RX/TX gain levels
• Status LEDs: Signal/Tone, TX/PTT
• Ultra-stable 1 ppm TCXO
• Bluetooth companion app support for Windows, macOS, Linux, Android, iPhone, and iPad

Estimated Power Consumption by Raspberry Pi Edition

• Receive: Pi Zero 2 W reference: ~400 mA (~2.0 W) · Pi 4: ~650 mA (~3.3 W) · Pi 5: ~850 mA (~4.3 W)
• Transmit: Pi Zero 2 W reference: ~600 mA (~3.0 W) · Pi 4: ~850 mA (~4.3 W) · Pi 5: ~1.05 A (~5.3 W)

UHF Version Measurements

All measurements in this section apply to the UHF version. VHF measurements follow in the section below.

Sensitivity Measurements

The 12 dB SINAD sensitivity was determined using a 1 kHz tone FM-modulated at a 2.5 kHz deviation and injected into the receiver. This provides an accurate representation of real-world listening performance, fully aligned with industry-standard SINAD measurement procedures.

Compliance Measurements

All tests conducted with a calibrated Vector Network Analyzer (VNA) and 36 dB attenuator. Worst-case harmonic: −63.56 dBc (3rd), far surpassing ETSI EN 300 220 (≥43 dB below carrier for ≤30 dBm TX). This offers an extra safety margin of >20 dB. Spectrum confirms excellent spurious suppression and clean transmission inside the 12.5 kHz channel.

Compared with top brands like Kenwood, Icom, and Yaesu, our module demonstrates superior spectral purity, placing it on par with commercial-grade equipment.

Spectrum

Harmonics

Channel Power

VHF Version Measurements

Sensitivity Measurements

The 12 dB SINAD sensitivity was determined using a 1 kHz tone FM-modulated at a 2.5 kHz deviation and injected into the receiver. This provides an accurate representation of real-world listening performance.

Compliance Measurements

All measurements conducted with a calibrated Vector Network Analyzer (VNA) and 36 dB attenuator. Worst-case harmonic: −53.07 dBc (2nd harmonic), comfortably exceeding ETSI EN 300 220 CE RED requirements. This provides an extra safety margin of over 10 dB.

The spectrum confirms excellent spurious emission suppression and clean transmission within 12.5 kHz bandwidth. Compared to leading brands (Kenwood, Icom, Yaesu), our module delivers equal or superior spectral purity, placing it in the same performance league as established commercial radios.

Measurements

Spectrum

Harmonics

Channel Power