Cheap 16-bit SDR RX / TRX - WEB-888 and TRX-DUO

Thanks to the rapid development and the wide use of SDR technology, it is possible to buy interesting devices at very reasonable prices. In addition, SDR technology allows new features to be added and devices to be upgraded without the need for intervention in the HW design.

For example, the software allows reception over the entire range up to 60 MHz and multiple users can listen in different segments independently. Each can use a different type of mode, and each can even use the built-in decoders - CW, FAX, RTTX, FT8, etc.

Here is the basic information on two very nice SDRs at reasonable prices.

WEB-888 16-bit SDR receiver HF + VHF

WEB-888 is an all-in one SDR receiver with 16-bit ADC LTC2208. The receiver is housed in a metal box and includes a LAN port. In addition, it also has a built-in GPS receiver - this allows you to tune the oscillator. The SMA connector for the REF signal can serve as a reference signal input, but also as an output of the internal generator, which is synchronized with the GPS. There are also GPIO outputs on the front panel for connecting an antenna switch that can be controlled from the WEB-SDR. The SDR can be used in a wide range: from a web-SDR receiver for 13 users, FT8 skimmers, to an eight band receiver for CW/RTTY/DIGI skimmers.

Main functions:

- Broadband: 1 KHz to 62 MHz and 118 MHz to 145 MHz

- 16-bit ADC DDC architecture SDR

- ADC chip LTC2208

- 61.44 MHz real-time bandwidth

- Built-in GPS module

- Gigabit Ethernet

- Reference clock input/output

- 24.576 MHz, 0.5 ppm TCXO

- 6 GPIO for antenna switching

- Zynq7010 FPGA with dual A9 ARM

- Alpine Linux 3.20 with Linux 6.6 Kernel

- WebRX-based browser SDR experience

- KiwiSDR web socket protocol for applications

- WSPR, FT8 skimmers, and other decoders

- 13 RX channels and 13 spectrum channels simultaneously

- Read-only root partition to prevent SD card corruption

- Aluminium enclosure

- Dimensions (with connectors): 115x70x25 mm

You can buy it there: HamParts.shop

TRX-DUO two channels 16-bit SDR receiver, 14-bit transmitter up to 60MHz

The TRX-DUO is similar in concept to the WEB-888, but includes a pair of 16-bit ADCs and a pair of 14-bit DACs. It is a full-featured dual TRX with a frequency range up to 60MHz. This concept makes it possible to use the two RX chains to phase each other and achieve diversity reception. Or create a SO2R TRX. Thanks to the SDR concept, it is possible to insert an SD card with different applications. From an SDR TRX to an eight band receiver for CW/RTTY/DIGI skimmers. 

Main functions
- Broadband: 10 KHz to 60 MHz
- Double 16-bit ADC DDC RX architecture SDR
- ADC chip 2x LTC2208
- Double 14-bit DAC TX architecture SDR
- DAC chip AD9767
- 61.44 MHz real-time bandwidth
- Sample rates 125 MS/s
- Gigabit Ethernet
- Zynq7010 FPGA with dual A9 ARM
- Read-only root partition to prevent SD card corruption
- Compatible with RedPitaya SDR board
- Aluminium enclosure
- Dimensions (with connectors): 115x70x25 mm

You can buy it there: HamParts.shop

Technical articles:

Here you will find simple technical articles to get you started experimenting with SDR. Most of the time it is very simple, just copy the image to the SD card and then proceed to the web interface. Watch out for the right type of SD card.

There is link to the blog.

Pre-installed SD cards:

To simplify the work with SDR we offer pre-installed SD cards. Simply insert these into the SDR and proceed according to the notes in the technical article.

You can buy it there: HamParts.shop

Cooling:

The enclosure of SDR also includes a fan. However, it does not include any dust filter. In the TRX-DUO, the fan is also very small and noisy. If the fan stops, it can very easily destroy the ADC or CPU. For these reasons, I offer an additional fan that easily slips onto the SDR. It allows you to adjust the fan speed and includes a basic dust filter.

You can buy it there: HamParts.shop

RF limiter protection:

It is very important to note that these SDRs have no input filter or protection. The SMA input is connected directly to the ADC via a transformer. Therefore, it is important to keep two things in mind:

- connect the RX antenna through a filter that limits signals to a maximum of 30 (60) MHz (antialiasing)

- protect the input from strong RF signals (custom transmitter) and storm surges

To protect the input from strong signals and spikes, we offer RF limiters. Their feature is to limit the RF signal amlpitude to a certain maximum value and thus protect the device. More information can be found on our website: RF LIMITERS

RX AUDITE VHF - version for 6 and 4m

This is new version of RX Audite. Redesigned for 50 and 70MHz, including filters, LNA with PGA-103+ and rest protections and switching as in the classic one.

You can find more at our web: https://hamparts.shop/rx-audite-vhf.html

This is the ideal solution for monitoring both 6 and 4m bands using one dual band Yagi antenna. However, you can also use it on one band and monitor, for example, both FT8 bands (50,313 and 50,323), or monitor the analog segment (beacons) and the FT8 one at the same time. This allows better monitoring of propagation conditions. RX AUDITE VHF also includes LNA and bandpass filters to limit signals from HF and FM BC transmitters.

Application:

- 6 and/or 4m RX splitter

- Monitoring both FT8 segments at 6m

- Dual band antenna splitter to 6 and 4m

- Web SDR and skimmer

- RX protections

- Low Noise Preamp and filters

 RX Audite - TRX/SDR splitter and switch

This is my new RX splitter and TRX switch. Including string of protections, optional preamplifier and INBAND RX antenna input. You can find more at: this link.

Main functions:

• Frequency range: 0,1 to 60 MHz
• Main TX/RX ANT splitter to two RX
• RX RF limiter protections for both RX outputs
• Isolated SDR RX output + Common-Mode filter
• HPF (> 100kHz), high voltage and current protection at both RX outputs
• INBAND RX ANT input - works only for SDR output
• TX-RX switch controlled by the PTT
• Designed for 2nd RX, WEB-SDR, SKIMMER or Panadapter
• Controller OFF = TX/RX ANT port to SDR RX out via RF limiter protections - Skimmer/web-SDR
• Controller ON = TX/RX ANT port splitted to TRX and SDR RX out via RF limiter protections
• TRX TX to main TX/RX ANT = SDR RX out to dummy load or INBAND RX ANT input via RF limiter protections
• Front panel Switch - SDR RX output to INBAND RX ANT all time
• Preamplifier (optional): insertion loss compensation, up to 14 dB of additional gain
• Preamplifier could be ON for SDR even controller is OFF (both by the front panel switches)
• Very high isolation when TRX TX and SDR to INBAND 100 dB @ 14 MHz and 80 dB @ 50 MHz
• Please, see also Frequently Asked Questions There FAQ

One black box but many different parts inside:

• TX / RX switch controlled by PTT signal
• PTT splitter (IN/OUT) in sniffer mode (IN directly to OUT) or output PTT FET switch picture
• 2-way RX splitter with low loss
• 2 x RF limiter RX protections - the best on the market :-)
• RX switch for INBAND RX antenna (only for SDR output) settings
• Both antennas with HPF > 100 kHz
• RX preamplifier (high IP3, 18 dB gain) with variable ATT - OPTIONAL link
• RX lines with High Voltage protections > 60 V AC
• RX lines with SuperFuse current protections > 100 mA
• Very high isolation TX to SDR, between RX ports, INBAND RX and TX/RX ANT port

Parameters:

• Supply voltage DC + 12 to 14 V (13,8 V recommended), DC plug cable
• Supply current DC max. 0,7 A with preamp
• Maximal TX power 250 W, recommended 200 W
• Very high isolation when TRX TX and SDR to INBAND 100 dB @ 14 MHz and 80 dB @ 50 MHz
• PTT IN compatible with 5V logic or higher, TX = GND
• PTT OUT sniffer (IN=OUT) or output FET (max. 35V DC and 0,5 A) picture
• PTT is not designed for QSK but you can use with right PTT lead/tail/TX delay time: min. 10/10 ms
• Default configuration SDR to INBAND RX ant input while TRX TX settings
• Optional Preamp preset to insertion loss + 6 dB (total gain abt 10 dB)
• Low insertion loss see measurements picture

RF limiters:

• Limiter for RF signal to + 13 dBm = 20 mW (could be + 17 dBm) @ 50 Ohm
• Current SuperFuse - the only at market
• Can survive high input power (current) for long time
• The soft clipping reduces the IMD products of a classic hard diode clip limiter

Internal Preamplifier module: (OPTION / version with preamp) link

• Preamplifier could be retrofitted also by you - customer
• High IP3 preamplifier module with 18 dB gain
• With 2SC5551 transistor
• Real OIP3 is +34 dBm
• Preset to 40 mA @ 13,8 V
• Low Noise Figure (NF) < 2 dB (60 mA 50 MHz)
• Variable gain by output ATT
• Preset to 10 dB for TX/RX ANT to both RX outputs = insertion loss + abt. 6 dB (1S) of gain
• Bypass relays
• Could be switched ON even the controller has got power switch OFF - preamp for SDR output.

 6 and 4m MSK144 and FT8 skimmer OK2ZAW/2

There is new Es season starting on VHF bands. I have seen interesting DK8NE 6m skimmer (link) for more modes. I do have Proxmox virtual server under the roof in 40m above the ground. Why not to run one more VM, add 4m dipole with filter and LNA for RTL-SDR (70MHz) and RSP1 (6m). There are some photos. You can find spots at:

50MHz & 70MHz OK2ZAW/2 in JN79xn

3D printed insulator for 70MHz dipole

Screen

CQ WPX RTTY SOAB SO2R by OK6W NEW EU RECORD?

After last year, when I run Single op 80m and win the World with NEW WORLD record, I left QTH to Pavel OK1MU. In BARTG RTTY where we tried SO2R all bands for the first time, Pavel made decision to try the same with 2BSIQ SO2R in WPX.

 Our cat Marous

10 + 15m and 40m 2el moxon

Stack for 15m and 20m

And new 500W wind generator

 

From Pavel OK1MU:

In the past years I participated in the SOSB20 and SOSB40m.  This year I decided to run  SOAB HP category for the first time. Because our QTH OL7M is building for MS-MM category, several adjustments were needed to control all the bands from one workstation. My big thanks to Jan OK2ZAW, who prepared and completed all setup and even prepared great meals! Everything worked without a single mistake full time. Great job!!!

I also used SO2R for the first time with 2BSIQ for the whole 30 hours and I was very excited. The final result due to using SO2R is brutal compared to the conventional SO1R ! Thanks to 2BSIQ I was never bored for a single minute of whole contest, hi. I have never spent so many hours preparing the best working strategy before the contest like now. This was absolutely essential to make this success. Due it I was satisfied with the chosen strategy. Despite the average conditions I worked 750 x NA, 160 x JA and 102 DXCC.

Thank you for the nice online match on Live score with Krzysztof SN7Q, Rich CR5V and Bud AA3B ! Adrenaline and fun during the contest were again a one level higher!

This contest was an unforgettable experience for me, culminating in a new European record.

RBN for OK6W:

During the contest I tested RedPitaya on K9AY loop without any preamp and filters! Just with my impedance transformer and protections. It was incredible, how K9AY loop worked also during TXing. It is only abt 30m from TX antennas. RedPitaya showed +10dBm of own signals :)