Sunday 7 November 2021

QRP Labs does it again - a revolutionary digital SDR transceiver - the QDX

 QRP Labs have done it again. And designed a revolutionary SDR Transceiver for digital QSOs.

The QDX

It uses SDR techniques for reception generating audio IQ signals and DSP techniques for RX, and an amazing new digital signal generation technique for TX.

Design highlights

1. Si5351 VFO with a very stable TXCO, generating directly RF IQ signals for the detectors.

2. Normal Tayloe IQ detectors, feeding an on board DSP processor for USB reception

3. Digitally switched bandpass filters for four bands, 80, 40, 30 and 20m on RX, and electrically switched LPFs for TX -  no relays!

4. > 5W output from 9 or 12V supply

5. A new transmit chain, that does not just take the audio output of the PC and send it to an SSB transmitter, as most designs today. But detects the input audio frequency and programs the Si5351 synthesiser to generate the RF tuned frequency PLUS this audio frequency for direct transmission. With an output stage which is pure digital switching. Simplicity though superb software proprietary coding. 

6. CAT emulation for TS480 

7. Integrated sound card and single Audio + CAT interface to your PC. (All in the single microcomputer chip)

This is how it is done

Block diagram

And all this in a box for $80. Remarkable, of course with the current shortage of semiconductors it is not available. But I guess I could show willing by placing my order... no I can't ordering is not open!


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