Having got my IC-705 working with the MX-P50 amplifier, I thought it was time to do the same with my Elecraft KX3 and my ELAD FDM DUO. In theory, there should be no problems interfacing them, but I did of course have to sort out connecting leads.
The MX-P50 has a rather odd connector for the PTT signal and because I want the option of using a few different radios with the amp, I decided to cut it off and replace it with Anderson PowerPoles for the sake of uniformity (plus I've got loads spare). With that job done, it was easy to start making up interface cables. To remove the risk of me connecting power to the amp’s signal lead by mistake, I fitted blue heatshrink tubing to the amp’s signal lead and the interface cables.
I already had a generic KX3 amp-lead which was terminated with a male phono connector (RCA). At first I was going to snip off the phono and fit powerpoles, but I thought the phono connector might come in handy at some point in the future with another amp, so instead I kept it and made up a short patch lead to convert it from phono to powerpoles (as seen in the photo above).
At the other end, the KX3 lead has a 2.5mm TRS jack-plug which connects to the phono-plug thus...
TIP : not used
RING : Centre-Pin (PTT)
SLEEVE: Shield
Once the lead was made up, it was time to connect the amp and radio together and test it. I set the KX3 to a power output less than 2W and switched to DATA mode for a constant carrier.
I attached a power-meter fitted with a dummy load, set the band selector to match the radio and transmitted. With 1.5W in, the amp put out around 25W. Perfect for Foundation License holders!
Brief video showing it in action
The next job was to test the lead I’d made up for my ELAD FDM DUO. This went slightly different to the other radios in that the output was around 23W no matter what the output power of the Elad was! Still, pretty much on the money for a Foundation Licensee.
I recently saw a post on Facebook where Bob Nagy (AB5N) had fitted an internal speaker to his QMX+ and I was keen to do the same, so I ordered the same Audio Amplifier and what I believed would be a suitable speaker.
When the components arrived, I realised that it wasn't immediately obvious where to make the connections between the audio amplifier and the QMX+ PCB, so I contacted Bob and asked him for help with the connections.
Very kindly, Bob obliged and told me where the connections go. Honestly, this is the sort of help that few people can be bothered providing and I gotta say that I am extremely grateful for his assistance and guidance 👍👍👍.
So the first job of course was to dismantle the QMX+ and decide where to place the speaker. There's plenty of room in the cabinet, but I was still keen to position it in a location which gave it the most clearance. One thing that crossed my mind was "Might there be an additional upgrade pcb from QRP-Labs in the future that might force the removal or relocation of the speaker"? Who knows?
Anyway, I picked a spot and marked four 5mm mounting holes for the speaker. Then I drilled another series of holes for the sound to pass through. To prevent bits of dust and crap falling through the holes and sitting on the speaker cone, I fitted a fine black gauze over the speaker(my apologies to the wife - she's convinced she had a new pair of black tights somewhere) 😂.
It's worth noting that I used a pillar-drill when drilling the holes - using a hand drill will almost certainly lead a messy set of misaligned holes. And make sure you use a new, good quality metal drill bit.
You need a short length of thin shielded cable to connect to the headphone sub-pcb. I say thin because there’s already almost no clearance between the pcb and the bottom of the enclosure, so adding a cable makes it even tighter!
You also need some regular cable to connect to the speaker and to a suitable power feed.
Bob had chosen to pick up the power for the audio-amp from the QMX’s power-connector and I did the same, but I’m sure there’s other options available if you know how to read the circuit diagram. To make it simple for others wanting to try this simple mod, I've done a sketch showing the layout of the wiring...
Figure 1
With the QMX+ dismantled, attach the shielded cable to the underside of the mini-pcb and feed the cable through one of the holes of the main pcb as shown below.
Connect the other end of the shielded cable to the IN and GND of the amplifier board as shown in Figure 1, putting the shielding to GND and the center-core to IN.
When you've completed the soldering, use a double-sided sticky pad to attach the audio amplifier to the back of the radio's rear panel (middle top) and start to reassemble the radio.
All that's left to do is pick a spot for the loudspeaker and drill the holes. Unfortunately, I had no black bolts for my speaker mounts, so I had to fit silver for now. I've ordered some replacements to make it look nicer.
That's it! All working well. I should point out that Bob said to change the Volume Increments to 2db because the QMX+ will over-drive the little amp. During final setup and testing, you might want to look at adjusting the trimpot on the amp for best volume levels. Just experiment 👍
Just a note on the feed from the underside of the PCB - I think (now) that it might be possible to pick up a feed from ABOVE the board to save squeezing that shielded cable underneath. See the diagram below and make your own mind up...
Anyway, it's all done for now and I'm happy with the mod and the way it sounds. Thanks again to Bob Nagy for his help 👍.
The ELAD FDM DUO is a fabulous 160-6M SDR transceiver which can not only be used as a standalone rig, but also has some superbPC software! To many, it's the KING of HF SDR QRP!
ELAD Elettronica was established in 1990 by Franco Milan - a designer with decades of experience. ELAD excel in technological innovation and skills in the world of electronics. They are electronic engineers first and foremost, producing high end test equipment, but being Italian, also have an eye for beauty and style - this thing wouldn't look out of place in a stylish lounge!
The FDM DUO is a smart, compact (7"x6"), very 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 - enabling 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 typically output 5Wat 12V and up to 9W at 13.8V (and down low into the mA range ) 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 full TX power when playing outdoors. It's worth noting that the Elad has a current draw of 500mA in receive mode, so this would be considered too high for many POTA/SOTA operators. I wouldn't let that bother me for a POTA outing because I've always got my truck close to hand with extra batteries, should I need them, but for SOTA that's a different story. Back in the shack (where a radio like this would probably spend most of its life), a 13.8V PSU will always guarantee max power out.
The Elad FDM DUO is a Direct SamplingSDR which means that the antenna is virtually connected directly to the A/D convertor. The advantage of this is that once a signal has been digitised, it's no longer prone to degradation, so the sooner you can achieve that, the better.
The RX range of the Elad is 10Khz to 52MHz, so it is also a good choice for ShortWave Listeners. Performance below 54MHz is superb and if you use the PC software you can actually go much higher (at reduced quality).
You can choose from Black or Silver finish, but me being me, I opted for the Special Edition "RED" version in 2019. 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 blue buttons below the LCD-screen access the most important functions directly, while less frequently used settings are available via menu system.
On the rear of the panel you have an RF OUT (0db), REF IN, RX-USB, two SO-239 connectors (one for a TX/RX antenna and one for an RX-ONLY antenna), PTT-OUT, KEY/PADDLE, RJ-45 MIC connector (Icom compatible), two more USB ports (TX & CAT control), a DB9 connector for accessories, a power connector and a small ON/OFF switch.
When connected to a PC, FDM-DUO is a very advanced SDR receiver and transmitter with capabilities which are usually available only in large radios. The device receives from 160M to 6M. A 16-bit ADC with 122 MHz sampling rate is built-in.
Selectable modes are:
LSB,
USB,
CW,
AM
FM,
Extra modes with the Software are:
Sync-AM
Multiple CW modes
DSB
ECSS
RTTY
WFM (incl. Stereo and RDS!)
RTTY,
DRM
IQ Out
The Elad has a built-in, onscreen CW DECODER, which is always a nice addition.
The accompanying 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!
Just stop for a moment and think about other Standalone SDR Transceivers on the market from the big boys like Icom and Yaesu - do they provide you with FREE comprehensive software?? No! Hell, you'd be lucky to get basic-control software.
Elad on the other hand provide FDM-SW2 (always being updated) totally free of charge and it permits you not only to control the basic functions of the radio, but let's you delve deeply into the nooks and crannies of the radio and change pretty much anything you want in search of a better signal.
You can 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 to fill your screen(s).
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.
The Noise Blocker on this radio is just staggering (to me at least)! Occasionally at my home QTH, someone in the neighbourhood switches something on 😡 which virtually wipes me out and the only noise blockers which can deal with it are the one on the Elad and the one on my TS-590SG (to a lesser extent). All others have failed completely.
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 with a stunning receiver which will never fail to impress you and the software just takes it to another level. It's also easy to hook up to a linear for those wanting to use it in the shack as their main rig.
Everyday operating of the Elad is really quite straightforward and although you do have to remember what some of the buttons do, it only takes a couple of days to feel completely comfortable navigating your way around all the options. The VFO dial is large and nice in the hand.
Although the screen is quite small, it is extremely crisp and easy to read - there's bags of information on there too. The colour of the backlighting can be altered and you can even set it up to change when transmitting - say to red.
When connecting up to a PC to run the FDM-SW2 software, I find it much better to use a TMATE-2 instead of mouse and keyboard. Having said that, you usually find yourself working a combination of the two.
If you want CAT Control, then you only need one of the three USB leads.
When you listen to the Elad, you just fall in love and forget about any gripes. This is an outstanding receiver!
You will note from the images that a matching speaker is available - the SP1A. External speakers from radio manufacturers are a great annoyance to me - I think they're outrageously expensive! Not so with Elad.
They cost £135 brand new and are super stylish and superbly well engineered! The SP-1A is an amplified speaker which conveniently has a PowerPole pass-thru. It has decent power output and has a built-in 3-stage DSP circuit. It fits in very well and completes the station.
To see the beautiful matching 100W Linear Amplifier, click the image below...
Here's a video recording of me speaking to W2RE using the ELAD and a G5RV...
This beautiful, high performance transceiver from Italy is a shining star in the SDR world, for sure. It's completely standalone but is backed up with some of the very best software available on the market for those who want to link up to their shack PC.
It's small enough to be thrown into a rucksack and be taken with you on your travels, but that (relatively) high current consumption will mean that you probably won't want to take it to the top of a mountain with a small battery. Having said that, not many people spend all day on top of a mountain 😁 You tend to bag your 10 contacts for the activation and enjoy the local scenery on your descent. My HobbyKing 8400 LifePO battery has never failed me.
I see the ELAD FDM DUO as a top-end performer that is absolutely perfect for the shack or Field Day or a POTA outing. You'd be very hard-pressed to find a better receiver - especially if you take advantage of the software on a computer, laptop or tablet.
I guess some people would baulk at the £1k price tag of a 5-9W radio and put their money into one of the run of the mill 100-Watters out there. As a lover of QRP though, I prefer to do things a little differently. Not everyone will. Are there better receivers out there? Of course - at three times the cost! Are they three times better? Of course not!
Here's a black edition that I bought for my static caravan. Up there in the Forest Of Bowland the noise levels are extremely low!
Dave Kennett (K8KFJ) put together 3amazingly useful videos on how to get the most out of the ELAD FDM DUO and I have to admit that there were plenty of tips that introduced me to features I wasn't even aware of! Bear in mind though, that these videos are for owners of the Elad who want to invest time in learning everything about this wonderful transceiver. They are not reviews.
ELAD GUIDE - Part 1
ELAD GUIDE - Part 2
ELAD GUIDE - Part 3
RX Stand-Alone Specifications
Frequency range: 10kHz - 54MHz.
Direct sampling receiver operating @122.88MHz, ADC: LTC2165 16bit.
DDC (Digital Down Converter) made with FPGA Xilinx Spartan 6.
Filters & Std-Alone Demodulator made with ARM STM32F4 microcontroller with floating point unit.
Demodulation: CW, CWR, LSB, USB, AM, FM narrow.
Selectable LSB and USB filters; 1600Hz to 3100Hz with 100Hz step plus 4000Hz, 5000Hz and 6000Hz values.
Selectable AM filters from 2500Hz to 6000Hz with 500Hz step.
Selectable CW filters; 2600Hz, 1500Hz, 1000Hz, 500Hz, 300Hz and 100Hz plus 4 CW peak filters applied after 100Hz filter to obtain an overall filter of 20Hz bandwidth.
Selectable FM filters: narrow, wide and data.
Pitch setting: up to 1kHz with 10Hz step.
RIT feature.
Three audio volumes: main, auxiliary and sidetone.
Squelch: off and 10 on levels.
Gain Control: automatic (AGC) and manual, with settable threshold.
Noise Reduction: off and 10 on levels.
Noise Blanker: off and 10 on levels.
Auto Notch: off and 2 on levels.
TX Stand-Alone Specifications
Supports bands from 160m to 6m.
Modulation and filtering made with ARM STM32F4 and DDS AD9957 with 368.64MHz clock.
Modulation: CW, LSB, USB, AM, FM narrow.
Microphone input (ADC 48KHz@16bit) with selectable gain (+/-12dB). Tx bandwidth selectable. Compression gain settable.
Key and Paddle input for CW operation, supports Iambic A and B, settable CW speed for Paddle, settable CW delay.
Not filtered 0dBm output on SMA connector (can be used as test equipment or as digital RF generator).
Up to 5W output power on all bands plus Max Selection (e.g. 8W@14MHz).
PTT Output to drive external amplifiers.
Main Features
VFO A and VFO B, with dedicated frequency, step and mode.
200 MEMORIES with dedicated frequency, step, mode and alphanumeric label.
QuickMem feature: up to 20 re-callable memories for band selection (memories 180 to 199).
QuickStep feature: allows to quickly change step without modify VFOs or MEM step.
Tune feature to facilitate antenna tuning with external antenna tuner.
VFOA=VFOB feature.
VFO to MEM and MEM to VFO features.
Std-Alone Split feature, VFO A for RX and VFO B for TX.
2 customizable keys (F4 and F5) with various functions: CW message sending, split management, tuning knob lock, CW/CWR choice.
2 frequency entering modes : with step and digit by digit.
Integrated CW decoder.
LCD color programmable with RGB values for the various operating modalities (RX, TX , PC remote control, ...).
All programmable components (ARM RX, ARM TX, Flash for FPGA, User Interface microcontroller and USB controller) are firmware upgradable.
General Specifications
Antenna connectors: RTX SO-239, RX SO-239.
CAT USB control interface with FTDI controller, manages also RTS and DTR signals to transmit.
Proprietary EXTIO Interface to connect accessories.
10MHz Reference Input on SMA connector.
Power supply: 2.1mm DC Plug, 13.8VDC.
RX consumption: typ. 500mA@13.8VDC.
TX consumption: <2.2A@13.8VDC (5W output).
Size: Width 180mm (7.00"), Depth 155mm (6.10") including Knob and connectors or 130mm (5.10") only enclosure, Height 70mm (2.75").
