Friday, 1 November 2019



My FLEX-3000 was a lovely rig and the software was pretty cool too, but it was kinda big and ugly and if I wanted to take it outdoors (at the bottom of the garden or up in the hills), it would have been a bit of a palaver! The Elecraft KX3 is pretty much perfect for the job, but that always felt much too "precious" and there was no dedicated PC software for it. The ELAD FDM DUO on the other hand is a superb SDR transceiver which can not only be used as a standalone rig, but also has some superb software

The FDM DUO is a smart looking, compact, well constructed radio which can be used as a standalone QRP radio up on a SOTA Summit or is equally happy at home in the shack connected to a linear amplifier. If one receiver is not enough for you, then simply connect it to your PC and run the FDM-SW2 software - then you can work on two separate bands at the same time with four independent frequencies on each band - effectively 9 receivers in total!

Depending on the power supplied to the radio and the band used, the FDM DUO will output up to 9W in all modes (except digital). Output drops according to the voltage of your supply, so using a low-voltage battery will drop the TX output typically to 5W. Personally, I use a 13.2V LifePO battery so I should get close to my permitted TX power when playing outdoors. Back in the shack, a 13.8V PSU will always guarantee max power out.

You can choose from Black or Silver finish, but me being me, I opted for the Special Edition "RED" version.  This special edition came about after Martin Lynch reviewed the radio on YouTube and suggested that it was "like holding a Ferrari in your hands", so the MD of ELAD decided to do a short run of red radios, lol.  The finish on the steel case is very nice and looks pretty durable. The legs at the front of the rig might look a bit flimsy but they are in fact quite robust. The VFO dial feels smooth and dependable and the screen is bright and crystal clear.

Under the cover: there's a very fast analog-digital-converter which samples the received HF directly into digital signals and a downstream DSP module provides for filtering and processing, while another ARM processor handles the signals of the control unit. One highlight of the FDM-DUO is the possibility to use it standalone without a computer. 

It's a perfect companion for QRP fans, allowing you to have an advanced SDR with you even when you're working far from home. The controls are very easy to use for a small QRP transceiver and in addition to the big VFO knob, there are two smaller knobs for volume and filter-center/width (amongst others). Six buttons below the LCD-screen access the most important functions directly, while less frequently used settings are available via menu system. 

When connected to a PC, FDM-DUO is a very advanced SDR receiver and transmitter with capabilities which are usually available only in very large large radios. The device receives from 160M to 6M. A 16-bit ADC with 122 MHz sampling rate is built-in. The only down side to the PC connection is that it uses up THREE USB sockets.

Receive modes are
AM (incl. Sync-AM), 
WFM (incl. Stereo and RDS!)

The transmitter also has a HF output jack with 0 dBm output. 

The PC software is called FDM-SW2  and is constantly being updated. The software gives you a staggering amount of control over the radio - much more than any other SDR software out there! 

You can, of course open multiple windows and spread them across your monitor in a layout which suits your method of working and they can even be spread across multiple monitors. One big plus to me, is the fact that you can properly resize windows - unlike for example - the ICOM RS-BA1 software which stays annoyingly small on screen!

Using the software, you can play with a great many features including the amazing 10 noise-blockers and 10 filters that are available for all modes. You can open up an equalizer to tailor your transmitted audio or adjust the level of compression. You even get a nice visual waveform to see your transmitted audio - a nice touch. 

Setting up pre-recorded voice messages (eg for calling CQ) is easily configured and these messages can be set to automatically repeat. If you have a USB headset or a USB microphone connected to your PC, you can choose which one to use to transmit from.

There's so much more that can be done from within the software - it really is quite amazing the amount of control the manufacturer has chosen to give to the operator. So much so, you might find yourself resetting the radio to the manufacturer's default settings when your tinkering has gone a little too far, lol.

The ELAD FDM DUO is a cracking little QRP radio and it has the software to match. It's also easy to hook up to a linear for those wanting to use it in the shack as their main rig. Optional extras are available like a BlueTooth module for controlling the radio from a phone or tablet, an external speaker, power amplifiers, etc, etc. The biggest bugbear to me is the need for THREE USB leads to connect fully to a PC. Crazy!

Here's a video recording of me speaking to W2RE using the ELAD and a G5RV...

Click HERE if video doesn't display

Thanks for visiting - please take a minute to leave a comment below 

73, Tom, M7MCQ.


PE4BAS, Bas said...

Wow Tom, looks like a great little SDR to have and play with. Great for those that have time to tinker with it. Hope to read more from you experiences with it soon. 73, Bas

MadDogMcQ said...

Thanks Bas. I'm ordering the DUO ART Linear Amp for it, which has an inbuilt ATU. Should be good fun.