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my  SDR tx/rx story and usefull links

mainly built with Softrock kits (v6,3) , FA-SDR, and more...

more than 1000 sold by kb9yig !

SDR 1 :Notes ( for entertainment purpose only ):

2009 : The project is a SDR Transceiver, all bands, with a 10W output power, to work most of the time SSB, on 17m, 20m and 40m.
As a collector of QRP rigs, I currently use a TL120 amplifier ( 100W ) to give more confortable signals to my partners. It will be used when necessary with the SDR.

I have decided to keep the rx filters and the 1W PA/tx filter from Softrock instead to move on to the MOBO project which gives a complete all bands TX/RX without manual change or switching. No serious reason for that, except at the time I bought the kit, MOBO4.3 was restricted to beta testers.
Costs of all my kits (Softrock 6,3 with all filters, PA2008, and extra LP filter) is around 200 usd, just a little bit less than the 6,3 + MOBO, as far as I know. So today, my choice would be different, may be. Learn about MOBO here 

Building the kits is easy, if you follow the instructions, it must work immediatly ( as several builder, I just had to replace Q7 on the main board...) - The few cms are easy to install if you have good eyes, or/and as me, the help of a glass. 
The most issue and the longer step is to find the right webpage where are written the answers to your questions ! 
I give a list hereunder to make your sourcing faster, but there are a lot of other people working on the subject.


Softrock 6.3 ( main board, filters for RX, PA and LPF for TX )
Availability, Pricing, and Ordering can be found at Tony's website.  check it every day, or every hour ! until he opens the door.... Unfortunatly he is victim of his success, and it becomes difficult to have the chance to put the order of the requested items. Now replaced by RX/TX ensemble, same design but all on one card, for 2 or 3 bands to choose yourself during building.

and immediatly register on the softrock group 
You will find a lot of answers, and may ask questions.

THE MAIN WEBSITE to build all softrock kits :How to build step by step 
( new site on )
USB I2C interface ( to get full control of frequency, band, ptt, and cw key, via the software )
See instructions on 
The driver is found at Fred Krom's PE0FKO website  
See also Fred's CFGSR web page  You need it to program the Si570 chip
Run the CFGR.exe program and follow the instructions on Fred's site.

Functional Test Setup
The functional testing of this kit assumes you will be using the Rocky SDR program  to control your Local Oscillator and set your center frequencies.

10W amplifier may be bought as a kit from DL2FI on QRPproject - easy to build and tune, it will work at first start.

I use a switchable filter from Virgil K5OOR available as a kit from HFprojects - no comment. 

All these kits are assemblied inside an ABS RFI shelded box available at radiospares ( find with google)   ref 501-581 190mm*110mm*60mm, on a prototype mother board easy to design yourself.

clic on the photo to see details 

- Rocky to download from Alex VE3NEA  - SSB is not included in TX mode.
- PowerSDR-iq release from SVIEIA works well in SSB (XP and W7 32bits)but you may get troubles with audio monitor in TX/SSB if you connect the local audio with VAC with a sound card like the E-MU202 that is not tested by Flex.See  - Automatic rejection of image  works very well in this release. See the with a lot of ideas and files to help in your configuration job. Also with the annoucement of a new high quality sound card USB2SDR by SV1EIA.
Download from and download the skins from the files on yahoo's group.

- Older PowerSDR by SV1EIA 1.12.20 solves the previous issue (XP only); I/Q Balancing is made by pressing the EIA button as shown on the photo hereunder ; the only soft to work SSB with 6,3 with my sound system ( USB box E-MU 0202 for I/Q IN and OUT, and a usb headset for local audio). One thing to know if audio output seems weak, move on one side the cursor of the Sub RX, as when let in the middle, the audio is off on a usb headset - download it from and download the manuel from the next link - I also use this release to work WSPR - See how I have done here.

My experience is there is not a "good" solution, but one that must (! we hope for you !) fit your design ( depends on the sound cards, the OS and the computer you are using - I tried with a Shuttle Atom Dual Core D510, and if the drivers does work well, the processor is not enough strong to get a good sound quality).

I use an E-MU 0202 usb sound box for I/Q in and out (192kb) , and an USB headset for local audio ( 48 kB - mic and speaker ). But I believe there is less issue when using a four channels sound card like the famous Delta 44.
Balancing of I/Q signals must be done with care, see also the procedure in SDR1000 Operation Manuel page 73*checkout*/powersdr-sr40/trunk/Documentation/SDR-1000_Operating_Manual.pdf 

And a lot of links to learn about these fantastic new toys :

Don't miss Alan pages G4ZVQ, a lot of usefull informations at 

To play with WSPR, read Alan notes on  and learn about this mode at K1JT pages - See my page to help in configuring the softwares to work WSPR.

To learn about VAC ( what is that ?) go on YT1DL site  , and enjoy digital modes. & download and install "build226" vCOM driver from N8VP  

Other links

Experiences and informations

- KD5TFD   -  N9VV  - DH1TW 

- Play with SDR without any hardware : web SDR  - webSDR - webSDR at W4MQ 

Et pour les pratiquants de la langue française , voir régulièrement les pages de F6CRP 

Where to find these radios ? clic here


SDR2 :  2010 :  FA-SDR-TRX  kit from DL2EWN, sold by Funkamateur (,  under following references :BX200 ( TRX ), BX202 ( 1W amp ), BX-026 (synthetiser with Si570 :FA-SY1), and BX-201 ( box : FA-Gehäuse zum FA-SDR-TRX) for a total cost around 240 Euro. This kit gives a 1 W SSB, CW, PSK, WSPR & co... ALL HF BANDS TRX from 160m to 10m, may be 6m ( didn't test) without any change of filter or any card as you do with the Softrock kit. Results seems as good as Softrock, may be more quiet and sensitive, but I cannot make serious measurements. Read comments on Tobias blog dh1tw  
An easy kit to build, complete, that will work immediatly with your usual softwares ( same as for the softrock). Only ONE day to build it, instead of 4 or more for the Softrock !
2011 : I have completed my FA line with a 10 W amplifier and the specific sound card USB2SDR made by SVIEIA - see details here
2012 : remote station with ghpSDR3-Alex client/server software running on a small Linux processor card - see the page  

NEXT TIME...may be

Although I usually do not build more than a transceiver in a century, (one analog monobander in the 20th, and the SDR Softrock in beginning of the 21th !), I have already exceeded this rule by constructing the FA-SDR this end of 2010 year !

may be the next one will be an Hermes based SDR, with digital I/Q and no need of balancing. See the wiki





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