Wednesday, December 1, 2010

SDR-2000.UA (ver 2.0) HF/50MHz All mode SDR

After years of research and dozens of experiments we would like to present you our version of SDR. This compact, light, sophisticated piece of hardware turns your computer into a modern, State-of-The-Art all mode Transceiver, giving you features that go far beyond the possibilities of any stand-alone mobile radio. 
•  One board 15 Watt SDR transceiver 
•  Optimized low noise DDS module 
•  Internal TCXO 
•  New Tx mixer 
•  Standalone one chip Pre-amplifier 
•  Embedded antenna switch + two Tx/Rx antenna connectors 
•  USB interface and FPGA control circuits 

•  100W PA (two RD100HHF) 
•  Internal ATU 
•  SWR-meter 
•  VHF/UHF converter 

Single board 15Watt SDR transceiver 
The is outfitted with individually optimized BPF to cover both the ham bands and for general coverage reception. These individually tuned filters minimize potential interference from strong out-of-band signals. Basic PA based on RD06HHF and RD16HHF transistors has ALC circuits. LP filter and 100 Watt optional power amplifier placed on the second board, under “main” board (not shown here). The real power of the is unleashed when it is combined with FlexRadio's PowerSDR software. 

Optimized DDS module 
First of all, all power and ground circuits of PA, DDS and mixer were re-routed. DDS output filter was completely changed. New filters for I and Q channels gave better phase characteristic, which improve IQ balance in modulator/demodulator while tuning. Usage of transformers present perfect galvanic separation between DDS and Tx/Rx ground circuits.  
Here is some result of modifications, done in DDS module. For comparison, we prepared measurement data from other TRCVR also. 

SDR  LO output, DS90LV028 pin #7 (Span 2kHz) 

SDR  LO output, DS90LV028 pin #7 (Span 40kHz) 

Elecraft K3 output LO1 (Span 2kHz) 

FT1000MarkV field  output LO1 

As you can see, phase noise DDS in near zone is better than 20dBc/Hz.  

Internal TCXO for Stable Frequency Operation 
Equipped with a temperature compensated crystal oscillator (TCXO) to provide the frequency stability needed for digital and CW mode operation, the TCXO has low level of phase noise and achieves frequency stability better than ± 0.1 ppm over the operating 
temperature of the transceiver once calibrated to a known frequency source, like WWV. 

Signal spectrum on the TXCO output 

Standalone one chip Pre-amplifier 
Build on SGA6289 chip. Pre-amplifier might be programmed by using “External control” settings in PowerSDR software. Use “pin #5 for pre-amp.  
For example:  
On 40-30-20-17-15-12-10 bands pre-amp will be always switched on. 

Embedded antenna switch + two Tx/Rx antenna connectors has internal antenna switch for two antennas. User can easily choose and 
program antenna for Tx and Rx modes separately, by using “External control” settings in 
PowerSDR software. Use “pin #6 for ANT switch. 
For example: 
-160 meters – ANT1 used for Tx and Rx 
- 80 meters – ANT2 used for Tx and Rx 
- 40 meters – ANT2 for Rx, ANT1 for Tx 

USB interface and FPGA control circuits 
One of the technological innovations was USB interface and internal 
peripheral bus, controlled by FPGA. Both this features introduced decrease of noise 
level, spurious pulse and save onboard space. 

Internal ATU 
The ATU will tune a variety of unbalanced antenna systems (coax) that facilitates its use 
with multi-band antennas where the SWR is less than or equal to 3.0:1 (dependent on 
the complex impedance of the antenna).  When used with an appropriate balun, 
balanced antenna systems can be utilized also. The ATU, when tuned and enabled, is 
also in the RX signal path further enhancing reception.  An ATU bypass function will 
completely remove the ATU from both the TX and RX signal paths.  All ATU functions 
are automatically controlled using FlexRadio PowerSDR as well as having manual 
control of the ATU. 
Network Type: Switched "L" 
Impedance Range: 17 to 150 ohms 
Power Rating: 100 watts 160-6m 

A compact footprint makes it perfect for fixed and portable operating positions 
One of the first things you will immediately notice about the is its compact 
(300 x 200 x 35mm) dimensions. One of the advantages of the compact footprint is that 
it allows for multiple installation configuration options.  It can sit underneath a laptop, it 
can be installed oriented vertically on its side to save desk space and can even sit 
underneath a desktop monitor. 

All measurement made on one RF test board: 
Mixer -  FST3253MTC 
LF driver - DRV135UA 
HF trans - Т4-1 Mini-Circuits 
Balance mod - AD5263 
Equipment used for measurements: Spectrum analyzers Tektronix RSA3308A, Service 
monitor Agilent HP8935 and other. 

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