2023-P-041-U | SVXLink Analog HotSPOT 70cm UHF PCB

Also available as a kit: https://shop.rf.guru/products/2023-k-041-u

Also available pre-assembled: https://shop.rf.guru/products/2023-k-041-u-pa

Experience the power of the SVXLink Analog Hotspot, a cutting-edge HAT designed exclusively for the Raspberry Pi Zero.

Packed with a formidable UHF 70 cm band radio module, this versatile device is accompanied by a state-of-the-art DAC/ADC, enabling it to function flawlessly as an EchoLink/SVXLink analog hotspot.

What's more, with the combination of a remote SVXLink with AnalogBridge (DVSwitch), you gain access to digital networks, including the Brandmeister and OpenDMR network, unleashing a world of limitless possibilities. 

 Datasheet

• Raspberry PI Pin compatible
• PCB ENIG (Electroless Nickel Immersion Gold)
• UHF 70cm band frequency: 400~480 MHz
• Tx and Rx frequency, Tx and Rx CTCSS, CDCSS can be set separately.
• Band width 12.5KHz / 25 KHz
• Output power 27dBm / 500mW
• RX Sensitivity：-124 dBm
• Adjustable RX en TX volume
• 1 ppm KDS TCXO crystal
• Wolfson WM8960 ADC/ 1W DAC 48khz
• Signal/Tone Blue LED
• TX/PTT Blue LED

Power consumption in combination with a Raspberry PI Zero W

• Receive modus 220mA
• Transmit modus 370mA

Kit Components

While we offer the option to purchase pre-assembled devices for your convenience, kit assembly is fairly easy (only 3 parts to solder) !

Hotspot

• 1 x Rf.Guru PCB
• 1 x 40 Pin Header
• 1 x SMA socket
• 1 x UHF SA818S Radio module

Hotspot enclosure (optional)

• 1 x Enclosure Top Part
• 1 x Enclosure Bottom Part
• 1 x Frontplate
• 2 x LED cover
• 4 x standoff FtF 11mm
• 3 x standoffs MtF 8mm
• 7x 2.5M 6mm screws 

Antenna

The RF 50 ohm output requires an antenna with a SWR (Standing Wave Ratio) of less than 4:1, which is considered reasonable. If you experience sound distortion, it could indicate that the antenna being used has a high SWR, leading to common-mode currents that may affect the RF chip. To test, use a 50-ohm dummy load (for UHF) and consider using a more suitable antenna. We recommend and sell antennas that work without any issues.

Assembly / soldering

Begin by soldering the RF chip, aligning it according to the layout. Next, solder the 40-pin header, and finally, solder the SMA connector.

Software

https://github.com/Guru-RF/SVXSpot?tab=readme-ov-file#svxlink-bookworm-image

https://github.com/Guru-RF/SVXSpot

Disclaimer

For those planning to connect their hotspot to a base antenna, we strongly advise incorporating an additional band filter. This essential component acts as a safeguard, preventing any potential signal interference due to harmonics.