softrock

[wb4jfi at knology.net]

I have at least one each of most of them, and some of the similar QSD/QSE radios.  They are good, lower-cost entries to SDR.  The crystal controlled versions were cheaper than the tunable ones, with the Si570 oscillator used on tunable units.  Most are better as single-band units, even though they may cover multiple bands.  Most of mine are for 80/40M, but I have a few for 30M or 20M.

If you mean the official Softrock kits from Tony Parks, they have a little SMT, but are mostly through-hole parts.  The SMT parts are the QSD/QSD switches, opamps, and bypass caps.  The SMT is generally easy to do for anyone that knows which end of the iron will burn your fingers.  You also have to wind all the coils, toroids mostly.  I can build most Softrock kits in less than an evening.  Winding the coils takes up the most time.

You will need some decent software, especially for transmit.  Since they are QSD/QSE-based, there can be significant image problems and carrier leakage if not tuned up right.

IMPORTANT:
The single-biggest thing to realize with Softrocks, like all QSD/QSE radios, is that your COMPUTER SOUND CARD is the MOST important part of the lash-up.  IT determines how good or bad your experience with a Softrock will be.  If you have a poor soundcard, you will have image reject problems, lots of birdies, a BIG spike at center-frequency, limited bandwidth spectrum display, and a host of other issues.  If you have a REALLY GOOD sound card, most of those problems just don’t come to play.  24-bit is not as crucial, but can show slight improvements.

You can spend $80 on a Softrock, but if you use a $10 sound card, there will be more problems.  If you spend $80 or more for a decent sound card, you will be rewarded.  A couple-hundred firewire-based sound card works real good, even at 192kHz.  Finding a decent/good USB sound card is a big challenge.  There used to be a good USB sound card, but it has been discontinued.  Most are pretty poor.  For desktops, get a decent internal sound card, or firewire.  For laptops, it’s firewire.  Or, an internal sound card if stereo inputs are found.

You will need STEREO inputs as well as outputs, for I and Q.  Most laptop sound cards are mono mic in, and don’t really work.  Well, they do, but you cannot get rid of the image of signals.

What are you planning to do with it?  For example, only messing with HF PSK31 does not require as wide a receive bandwidth as a general-coverage unit.  Sometimes only one frequency is required, such as CW QRP near 7056K, and a crystal controlled unit would suffice.  HF? VHF/UHF?

The RTL dongles everyone is buying are fun, but they cannot approach even a Softrock for a decent SDR on HF.  With only eight bits A/D the dynamic range is rather limited.  I measured only about 60dB at 100MHz on one of the ones that I have.  For HF, you should have nearly 130dB, according to Mitola.  Of course, it’s all relative.  Ya gets what ya pays for.

There are SDR programs for Softrocks for Windows, Linux, and Macs.  I’m most familiar with some Windows and Linux versions.  Rocky is probably the all-time simplest (www.dxatlas.com I think).

Does that help at all?
73, Terry, WB4JFI


From: Alex Fraser 
Sent: Saturday, May 25, 2013 12:15 AM
To: tacos at amrad.org 
Subject: softrock

Any opinions on the softrock kits?

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