SDR Radio Transceiver - Flex, Elecraft®, Cube, Softrock


SDR transceivers have become more popular and the development has been encouraged by many radio amateurs and somewhat surprisingly, not yet shown by the old guys, Kenwood, Icom and Yaesu. The SDR transceivers that have been introduced by other companies, Flex Radio Systems in particular, provide even more technical performance at a lower price than standards rigs. However, they have been depending on PC to be used. So far, the SDR Cube has been the only SDR transceiver without the always need of a PC. A while ago, Elecraft introduced the small all-band, all mode, 160 - 6 meter KX3 SDR transceiver, also without always-PC-need. Elecraft has become a very respected name for various qrp transceiver kits, available as pre-built too, as well as the K3, and other accessories too. The KX3 is the first HF transceiver on the market to provide all bands and modes in a portable unit, with many SDR features. It has a desktop design, as compared with the typical style as of the Yaesu FT-817.

The circuits that cannot be replaced with software, of course, is for the drive and final amplifier, antenna front end, microphone preamp, speaker amplifier output.

So, will SDR technology take over the market?

It will definitely change it but probably not take over. Compare with audio which uses a lot less frequency than RF. Digital electronics could therefore be implemented earlier in audio equipment, and was more and more introduced in the 80s. Looking at digital studio recording equipmen, there were digital units that emulated analog equipment and did more. However, in the early digital era, mostly buttons were used and one or two controls were used to control each parameter, either buttons or with a value knob too.

A couple of years later, analog and tube electronics became again popular. Since older analog equipment had used more controls and potentiometers, the manufacturers then included more of analog-feel-knobs, analog emulation in the digital equipment, and even tube sound emulation.

But still, certain analog and/or tube electronics is still considered as the best even though digital emulation in many areas not any longer can be distinguished from the "real thing". It was different for digital audio equipment because it was before PCs were common. Of course there were some of interface with midi, with Atari computers and it was used by home recording musicians. When PCs became more common, then it was used for audio too. For a while PCs have been used for radio and still will, but from now on, there will be more SDR transceivers without the always need for PC.

Will SDR-technology make transceivers cheaper?

Yes probably. SDR RF equipment is likely to become cheaper with today's competition. In a couple of years, SDR transceivers that can be used without a PC will become more common and then, with potentiometer controls which only the KX3 and the Cube have today. These should become cheaper as well, because of the fewer parts.

SDR transceivers

SDR transceivers in alphabetical order,



FlexRadio Systems

FLEX-1500, FLEX-3000, FLEX-5000A/FLEX-5000C

SDR Cube

SDR Cube


RXTX Ensemble


Elecraft® has made a name especially for their very popular transceivers K1, K2, KX1 and K3 as well as for other related ham radio equipment. The K1, K2 and KX1 are analog/digital qrp transceivers that are and have been available as kits, and in the K2, a 100 watt final amplifier can be built in. The K3 is larger transceiver with many features, making it among the best rated rigs.

The Elecraft® KX3 is a 160 - 6 meter meter all mode HF transceiver which is PC independent and yet portable. Even though the SDR Cube was the first portable, PC independent HF transceiver that was manufactured, the KX3 makes Elecraft® to the first manufacturer with both ordinary analog/digital as well as SDR transceivers. This is a definite move in the ham radio industry.

Since Elecraft® products have been held in high regard by many with uniformly positive reviews, it will therefore be interesting to see how the KX3 will be received.

Elecraft® KX3 (QRP) SDR SSB/CW/DATA/AM/FM transceiver

Elecraft® KX3 (QRP) transceiver

Elecraft® KX3 160 - 6 meter (QRP) SDR SSB/CW/DATA/AM/FM transceiver

**13 June, with the use of software defined radio design, which can be used without a PC, the Elecraft® KX3 SDR transceiver is the latest news in portable qrp transceiver technology. Although it has a 10 watt output, Elecraft® doesn't describe it as a qrp transceiver, maybe because of the KXPA100 amp option.

The Elecraft® KX3 It's analog performance is set high with the use of fast and high resolution AD conversion. It's overall performance is then accomplished with DSP which makes it possible to define the characteristics by means of software. Hence, as the software will be upgradeable, its performance will be improved as well. Furthermore, a number of other features are included such as dual watch and data modes. A DSP provides noise reduction, noise blanker, auto-notch as well as stereo audio effects with an 8-band audio equalizer. To read more about it, just check out the homepage.


Elecraft KX3 - elecraft.com

Flex Radio Systems

To see a technical overview of the Flex Radio sdr transceivers, look here.


Flex Radio Systems - flex-radio.com
Flex Radio Systems transceiver comparison - flex-radio.com
Flexcontrol - support.flex-radio.com
Support - support.flex-radio.com
Downloads - support.flex-radio.com
Flex Radio Systems forum - forums.flex-radio.com
Feature Request List - forums.flex-radio.com
Online store - flex-radio.com


Software Defined Ham Radio - w9oy-sdr.blogspot.com
The FLEX-3000 SDR Adventure - flex-3000.blogspot.com
DDUtil FlexWire Adapter - forums.flex-radio.com


Flex-1500™ - Click on the images for double size or here for a large image of the rear side.


FLEX-1500™ features - flex-radio.com
FLEX-1500™ manual - flex-radio.com
FLEX-1500™ installation guide - flex-radio.com
FLEX-1500™ Accessories - flex-radio.com


FlexRadio FLEX-1500™ Reviews - eham.net
Review discrepancy between Flex-1500 & Flex-3000 - eham.net


Flex-3000™ - Click on the images for four times the size


FLEX-3000 Transceiver Specifications http://kc.flexradio.com/KnowledgebaseArticle50352.aspx FLEX-3000™ features - flex-radio.com
FLEX-3000™ manual - flex-radio.com
FLEX-3000™ installation guide - flex-radio.com
FLEX-3000™ Accessories - flex-radio.com


FlexRadio FLEX-3000™ Reviews - eham.net
FlexRadio FLEX-3000 HF and 50MHz SDR Transceiver

FLEX-5000A™ / FLEX-5000C™

Flex-5000C™ - Click on the images for four times the size

To see the specifications and differences between 5000A and 5000C (and too 1500 and 3000 as well) look here

Flex-5000A™ - Click on the images for four/three times the size


FLEX-5000A and FLEX-5000C Transceiver Specifications http://kc.flexradio.com/KnowledgebaseArticle50044.aspx FLEX-5000™ features - flex-radio.com
FLEX-5000A™ details - flex-radio.com
FLEX-5000C™ details - flex-radio.com
FLEX-5000™ accessories - flex-radio.com
FLEX-5000™ upgrades - flex-radio.com
FLEX-5000™ manual - flex-radio.com
FLEX-5000™ installation guide - flex-radio.com
FLEX-5000+VU5K Installation Guide - flex-radio.com
FLEX-5000 RX2 Installation Guide - flex-radio.com
FLEX-5000 ATU Installation Guide - flex-radio.com


FlexRadio FLEX-5000A Reviews - eham.net
FlexRadio FLEX-5000C Reviews - eham.net
FlexRadio Systems FLEX-5000A HF/50 MHz Transceiver - Review in QST (July 2008)
FlexRadio Systems FLEX-5000A Software Defined Radio Transceiver - CQ Magazine
Softwaredefinierter Transceiver für den Amateurfunk: Flex-5000A [Aus Amateurfunktechnik"
FLEX-5000: La radio del futuro ya está aquí - CQ Magazine

SDR Cube SSB CW transceiver

Click on the image for the double size, or here for a large size.

The SDR Cube a one-band QRP transceiver with an embedded DSP controller coupled with a Softrock RxTx v6.3 RF front end. The size of each of the Cube's sides is 4". full, built-in user interface: graphic LCD for spectrum display, typical controls for frequency, mode and signal management, and I/O jacks for connection to the outside world. The Cube’s design is optimized to internally accommodate the popular Softrock electronics. Different from other experimenter “single board” solutions, the Cube was designed from the start to serve as a full transceiver. The SDR Cube is a totally self-contained, embedded software defined radio (transceiver) for CW and SSB operation. It uses a Softrock for the RF front end electronics (RF mixer, amplifiers and filters) and an embedded digital signal processor with software programmed to perform as an HF modem. This programmability is the essence of an SDR’s ability to dynamically support virtually any modulation mode. A personal computer (PC) is not needed. a blue graphic display showing the transceiver settings and an exciting 8 kHz-wide band scope of spectrum signals, and the popular Softrock RXTX v6.3 board. The SDR Cube may also be used with any of the 11,000 other Softrocks in the field today, via the expansion port on the rear panel. Many details are available at the product website (www.sdr-cube.com), and active online user discussion occurs in the SDR-Cube Group in Yahoo Groups.


SDR Cube - sdr-cube.com
SDR Cube Transceiver OPERATING MANUAL - sdr-cube.com
SDR SDR Cube - A Portable Software Defined Radio Utilizing An Embedded DSP Engine for Quadrature Sampling Transceivers - sdr-cube.com


Updated SDR CUBE Software - w0anm.com
SDR Cube Transceiver OPERATING MANUAL - sdr-cube.com
SDR SDR Cube - A Portable Software Defined Radio Utilizing An Embedded DSP Engine for Quadrature Sampling Transceivers - sdr-cube.com Latest Kit – SDR Cube - w0anm.com
Amplifier for SDR Cube - w0anm.com
SDR Cube – Next Generation SDR - dh1tw.de
SDR Cube - vk2rh.com
SDR Cube A Portable Software Defined Radio Utilizing An Embedded DSP Engine for Quadrature Sampling Transceivers
SDR Cube Transceiver


At this time, according to the kb9yig.com homepage, the only available transceiver kit is the RXTX Ensemble transceiver.


Softrock - wb5rvz.com
Softrock - kb9yig.com


Softrock reviews - eham.net

Softrock related:

Softrockradio - softrockradio.org
On this page, the maker of softrockradio.org mentions his ham radio parts store, which sofar is on a trial basis.
The Parts Place - thepartsplace.k5nwa.com

SDR buzz forum - sdrbuzz.com/forum
SoftRock Multiband Transcievers - sdrbuzz.com/forum
Softrock RXTX V6.3 - Xtall - Band Pass Filter(s) - golddredgervideo.com/wb5rvz

Softrock RXTX Ensemble kit

Click on the image for double size or here for a large image.

On the RXTX Ensemble page, it is said that the Ensemble kit basically is a RXTX V6.3 with the difference that its band-specific components are fixed and predetermined (as opposed to the plug-in daughter boards for these functions in the RXTX V6.3). So the kit isn't compatible with the Mobo add-on series, which depend upon the RXTX V6.3's plug and socket arrangements.

This transceiver kit comes in five versions: 160, 80/40, 40/30/20, 30/20/17 or 15/12/10 meters.

The SoftRock RXTX Ensemble Transceiver Kit provides a 1 watt SDR transceiver that can be built for one of the following four band groups: 160m, 80m/40m, 30m/20m/17m or 15m/12m/10m. Components are included for all four options and can be assembled at the builders choice. The kit combines the functionality of the prior SoftRock v6.3 RXTX+Xtall Transceiver Kit, the USB I2C Interface Kit and the PA Filter Kit on a single circuit board with connectors along one edge for easy access.


Softrock - kb9yig.com
SoftRock RXTX Ensemble Transceiver Kit - wb5rvz.com

Updated April 30th 2012

(When the images below are clicked at, the new images are in about natural size, approximated to an average screen pixel size of ~0.267mm. (If the screen's pixel size would be that, then natural size.)
The page is made mostly for Firefox browsers. / Now made so that it should look the same in Explorer.

Copyright © 2010 - 2012 - sdrtransceiver.com - SDR transceiver info