The astounding market capitalisation of NVIDIA begs the question, are we in another bubble, like in 2000, and was Bill Gates right when he pointed out that we over estimate short term effects and under estimate long term effects - in this case of AI. Listen here: https://www.abc.net.au/listen/programs/nightlife/peter-marks/106188550
A good net this morning with lots of nice Xmas cheer and looking forward to 2026 being a good year for FreeDV activity.
Stations on frequency included: VK2AWJ, VK2CJB,VK2NP,VK2YW,VK3AHC, VK3ANC,VK3BU, VK3FAR,VK3GTP,VK3KEZ, VK3PCC, VK5ABE,VK5COL,VK5KVA,VK5LA,VK5MH,VK5RT, and me, VK3TPM.
One station, John, VK2AWJ had outstanding audio quality (to my ear) he said he was using a Logitech headest - perhaps the close mic really helps.
The LARCSet is a 40m 5W SSB Transceiver Kit from hfsignals.com. It's just US$39. The VFO is analog and it's a descendant of the bitx40 line. Ashar Farhan says you can build it in a day and I can cornfirm that promise.
The board comes with the vast majority of components already fitted.
The work that needs to be done by the builder is winding a few toroids (although happly the three trifilar ones come pre-wound), assembling the front panel, fitting potentiometers, soldering crystals and a few transistors including the IRF510. The manual is very clear.
The front panel is held in place by the little screw nuts from the 3.5mm panel mount sockets and I found that there wasn't enough thread on these to hold it in place. I sanded down the front edge of the board and ended up gluing the nuts to better hold it in place.
My VFO toroid needed one extra turn to get it in the right range so bear that in mind when winding.
The varactor tuning is quite sensitive and I think a multi-turn pot or an additional fine tuning pot might be good idea. I like the idea of a totally analog VFO but amusingly QRP-Labs has just announced a compact digital VFO that could be suitable for radios like this. Here's a video showing unboxing, stages of the build, receiver testing and final completion.
I enjoyed the build and it received first go.
The radio has some rather serious problems. CW produces about 3W but the signal is modulated with a tone. Sideband is extremely weak - it seems that the single transistor microphone amplifier produces vastly too little audio for the mixer. I shorted R73, the feedback resistor in the mic amp, and got a bit more gain.
I found that the bandpass filter, L2 & L3, peaks a bit low - at 6.9Mhz - and I plan to remove a turn to improve sensitivity. Others have pointed out that the output low pass filter is a too aggressive.
Because of the low cost of the kit, shipping is a significant part. HFSignals is offering a pack of five and I'm going to suggest it as a group build project at my local club.
Here's a bit more of it receiving. The VFO is quite stable but tuning is very sensitive. I plan to add a fine tune control.
Here's a better quality rendering of the schematic (click to enlarge):
After following the instructions, rather than the board marking, I've got L4 and L5 in the right spot and now I'm seeing about 2.7W CW out which is a little disappointing but better than before.
The main tuning is quite course so I've added a 1K in series with the hot end and this makes tuning much better. Here's a demo:
I've developed a simple 3D printed case which is working quite nicely.
As someone not generally comfortable with CAD I've been enjoying the almost childlike simplicity of TinkerCAD. The other day, David, VK3KR, suggested I have a look at OpenSCAD. It is a very different approach. Rather than dragging shapes from a pallet and modifying them by dragging, you code the shapes you want.
I built a QRP L-Match some time ago, inspired by Peter VK3YE, but mounted in a small food storage box it didn't look great. Working in OpenSCAD looks like this:
You write code on the left and each time you save, the render updates on the right. Sometimes, I'd love it if I could drag something in the render and have the code update. Maybe one day. There's a button to export STL and it looks like it can talk to some 3D printers directly although I haven't tried this.
I particularly like that I can set variables and then use them throughout the code so changing things like the wall thickness is set once and updates everywhere.
My experience is about one day of playing so please don't take my code as a good example of best practice. Here it is though.
// Box for L match tuner
$fa = 1; // Minimum angle
$fs = 0.4; // Minimum size
wall_thickness = 1.5;
box_x=80;
box_y=65;
box_z=25;
overlap=0.001;
bnc_r=10.5/2;
bnc_holes=12.5/2;
switch_r=6.5/2;
poly_r=7/2;
poly_mount_r=3/2;
poly_mount_offset=7;
difference() {
// Outer cube
cube([box_x, box_y, box_z], center=true);
// Inner cube (subtract from outer to create hollow space)
// Inner dimensions: 20mm - 2*3mm = 14mm
translate([0, 0, wall_thickness + overlap])
cube([box_x-(2*wall_thickness), box_y-(2*wall_thickness), box_z-(wall_thickness)], center=true);
bnc_socket(z=box_x / 2);
bnc_socket(z=-box_x / 2);
// inductance switch holes in side
switch_spacing=10;
for (i = [0:1:4]) {
rotate([90,0,0])
translate([(i * 10) - 20, 0, -box_y / 2]) // push to the side of the box
cylinder(h=10, r1=switch_r, r2=switch_r, center=true);
}
// extra cap switch
rotate([90,0,0])
translate([0, 0, box_y / 2]) // push to the side of the box
cylinder(h=10, r1=switch_r, r2=switch_r, center=true);
translate([25,-15,0]) {
// polyvaricon main hole
rotate([0,0,90])
translate([0, 0, -(box_z / 2)+4]) // push to the base of the box
cylinder(h=10, r1=poly_r, r2=poly_r, center=true);
// polyvaricon screw hole
rotate([0,0,90])
translate([poly_mount_offset, 0, -(box_z / 2)+4]) // push to the base of the box
cylinder(h=10, r1=poly_mount_r, r2=poly_mount_r, center=true);
// polyvaricon screw hole
rotate([0,0,90])
translate([-poly_mount_offset, 0, -(box_z / 2)+4]) // push to the base of the box
cylinder(h=10, r1=poly_mount_r, r2=poly_mount_r, center=true);
}
}
module bnc_socket(z = 0) {
// end hole for BNC socket
rotate([0,90,0])
translate([0, 0, z]) // push to the end of the box
cylinder(h=10, r1=bnc_r, r2=bnc_r, center=true);
// mounting holes for BNC socket
rotate([0,90,0])
translate([bnc_holes, bnc_holes, z]) // push to the end of the box
cylinder(h=10, r1=poly_mount_r, r2=poly_mount_r, center=true);
// mounting holes for BNC socket
rotate([0,90,0])
translate([-bnc_holes, bnc_holes, z]) // push to the end of the box
cylinder(h=10, r1=poly_mount_r, r2=poly_mount_r, center=true);
// mounting holes for BNC socket
rotate([0,90,0])
translate([bnc_holes, -bnc_holes, z]) // push to the end of the box
cylinder(h=10, r1=poly_mount_r, r2=poly_mount_r, center=true);
// mounting holes for BNC socket
rotate([0,90,0])
translate([-bnc_holes, -bnc_holes, z]) // push to the end of the box
cylinder(h=10, r1=poly_mount_r, r2=poly_mount_r, center=true);
}
Here's the lid:
// Box lid for L match tuner
$fa = 1; // Minimum angle
$fs = 0.4; // Minimum size
wall_thickness = 1.5;
box_x=80;
box_y=65;
box_z=wall_thickness;
overlap=0.001;
// lid
cube([box_x, box_y, box_z]);
// inside
translate([wall_thickness, wall_thickness, 0])
cube([box_x-(wall_thickness*2), box_y-(wall_thickness*2), wall_thickness * 3]);
The downloadable binaries are quite old, dated 2021, but development seems active. I tried building the macOS version but it failed and I haven't persisted.
Although the learning curve on a code driven 3D design program is higher than a click and drag version there are benefits. Things like the row of holes for inductance switches is a loop and a single setting of the radius of the hole is used throughout.
A good FreeDV net again this morning with stations including VK2KNC, VK2SPB, VK2VCO, VK3CKY, VK3FFB, VK3JCO, VK3JFR, VK3KEZ, VK3SRC, VK3UH, VK5AG, VK5COL, VK5KFG, VK5KVA, VK5QI, and VK3TPM.
Thanks everyone for coming up and for all the season's greetings. Note that Jack, VK5KVA, will be hosting a net tonight from 20:30 Eastern Time also on 7.045Mhz.
Almost a week later, how has the ban been faring? We've heard some stories of kids getting around the ban, but overall has it been effective?
A summary of recent AI news including SuperHuman hearing aids for the wealthy.
Peter Marks, mobile software developer and technology commentator from Access Informatics, joined Philip Clark and listeners to Nightlife. Listen here: https://www.abc.net.au/listen/programs/nightlife/nightlife-tech-talk-with-peter-marks/106151168
A record rollup this morning although NVIS (local) propagation was poor. The best signals for me were from Sydney - Melbourne but South Australia was good too. Again we had some new stations and there was mention of the article in the latest Amateur Radio magazine and a new video from Peter VK3YE.
Stations on frequency, not all transmitting, included VK2AWJ (John first time on the net), VK2BLQ, VK2DWG, VK2JAB, VK2KNC, VK2SPB, VK2SPD, VK2VCO, VK3CKY, VK3CRY, VK3FFB, VK3GTP, VK3KEZ, VK3SRC, VK3PWG, VK3VB, VK3VKL, VK3YE, VK4XYZ, VK5COL, VK5KFG, VK5KVA, VK5UR, VK6KR and me VK3TPM.
As an aside.. it's wonderful to see so much FreeDV activity here in Australia. Here's the list just for one frequency on 40m today, a Monday.
FreeDV has really taken off in recent weeks.
