Wednesday, 12 February 2025
FORCED RETIREMENT!
Monday, 6 January 2025
MX-P50 INTERFACE 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
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.
TIP : PTT
RING : Not Used
SLEEVE: Ground
73, Tom, M7MCQ.
Tuesday, 3 December 2024
QRP-LABS QMX+ SPEAKER MOD
WITH BOB NAGY'S HELP!
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...
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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 👍.
73, Tom, M7MCQ.
Monday, 2 December 2024
ELAD FDM DUO
Selectable modes are:
Dave Kennett (K8KFJ) put together 3 amazingly 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.
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").
- Weight: 1.2Kg (2.4 lb), shipment package 2.2Kg (4.85 lb).
Operation Specifications with FDM-SW2 Software
- Up to 4 simultaneous virtual receivers in single channel mode.
- Up to 8 simultaneous virtual receivers in double channel mode.
- Dedicated Audio Channel for each virtual receiver.
- Dedicated CAT Channel for each virtual receiver.
- Supports connection with external programs using Virtual Serial Ports and Virtual Audio Cables.
- Selectable IQ USB stream in two main modalities:
- Stand-Alone : 192ksps single channel and 192ksps double channel,
- Remote : 384ksps, 768ksps, 1536ksps, 3072ksps, 6144ksps in single channel mode and 384ksps in double channel mode.
- Remote Split operation, VFO A for RX and VFO B for TX. TX frequency and TX mode are managed by FDM-SW2.
- Play Files feature. CW messages sending feature. Advanced Transmit Feature with Equalizer, VOX, Compressor, and Filtering functionalities.
- CW Skimmer integration management (DX Spot visualization & tuning capability).
- Direct Digital Modulation using FDM-DUO USB soundcard based on CMedia chipset digitally interfaced with ARM microcontroller.