Monday, August 13, 2018

New 10W 40m QSX40 from QRP-Labs

I very much enjoyed building the QCX CW transceiver and there have been rumours that QRP-Labs was working on a sideband version. It seems the rumours are true and the kit is being built at a "Youngsters on the air" meeting in South Africa at the moment.

It seems that it's a 10W output kit for 40m (and presumably other bands too) but nothing formally announced or available for sale at this time.

There's a few comments in the QRP-Labs forum, a tweet, and some clues in the Facebook page of YOTA. I'm very much looking forward to learning more about this kit.

Great that they're testing the build process on a group before launching it. I can wait and would rather build a debugged kit with accurate manual rather than rushing in too soon.

Just spotted this interview with Hans:


There's a lot of information in the video, I've taken notes to make it easier to take in. The new rig features:

  • 10W SSB, AM & FM
  • USB CAT control and Audio
  • USB host for keyboard to use with no-PC PSK31, RTTY & CW (decodes to the display)
  • Iambic CW keyer
  • 40m initially and later 10 band
  • Real time clock (with provision for battery backup)
Hans has worked on this for over 6 months.

Designed a 40m 10W SSB transceiver kit. It will also do AM and FM.

It's an all software defined radio, with no PC necessary. Internally it uses a powerful 32 bit ARM processor. The user interface is quite minimal, just two rotary encoders and four buttons. It’s designed to be used with a standard iPhone/Samsung headphone with mic. There’s an RJ45 mic socket on the back for a Yaesu/Kenwood standard mic.

There’s two USB sockets, one A and one B. You can plug in a USB keyboard which you’ll be able to use with PSK31, RTTY and CW. Decoding will be displayed on screen standalone - again no PC needed for those modes.

If you plug a computer into the USB B socket the rig will appear as a 24 bit sound card so you can use it with a PC for digital modes such as FT8.

Like last year’s QCX, it has built in test and alignment hardware and software.

It’s a high performance radio using a 24 bit A/D converter chip for high dynamic range and a 24 bit D/A on the output of the SDR. The large heatsink is designed to handle continuous digital modes without overheating.

In the next couple of months a plug-in filter board will be designed which will let the rig cover 10 bands from 160m to 10m. (This will include the 60m band).

There will also be an optional extruded aluminium enclosure.

The exact price hasn’t been decided but it’s hoped that the 40m single band version will be about US$75 and the whole thing including the 10 band filter board and enclosure will be about US$150.

There's a thread discussing this enthusiastically on Reddit.

Tuesday, August 07, 2018

Windows 10 - still not finished

While my iOS phone is undoubtedly the computing device used most often in my day, when I want to do some serious computing work I use macOS and Linux. There is some software that still only runs on Windows so I have a Windows 10 computer. Windows can be annoying but it's superficially looking much nicer these days, but from time to time cracks appear.

I use "natural scrolling" where the direction of the trackpad or mouse wheel moves the content as if you were scrolling on a touch screen. On Windows 10 I have a Logitech wheel mouse and I wanted to make it work the same as every other mouse here.

First I go to the Mouse settings which looks like this:


Nowhere in there is scroll direction so I click "Additional mouse options" and I'm thrown back into a Windows 95 settings user interface:


Wow! they haven't got around to updating the settings to the new look. This must make it hard for touch screen users. I looked all around here and there is still no way to switch the direction of the scroll wheel.

I found the answer here. Unbelievably, one must get the HID device path, open the registry editor and set 1 as the value of the "FlipFlopWheel" property (after navigating five levels deep in the hierarchy).

A lot of older Windows software runs well under Wine on Linux. That may be the ultimate answer.

LTSpice seems to run just fine on Linux under Wine.


Saturday, August 04, 2018

Another van trip north

I've just returned from a few nights away in northern NSW. On this occasion the driving was shared with another ABC alumni, Peter Cave.

We're not sure if the van is driving better or if it's just that we've got better with the worn gears, but it seems smoother. It's still using a bit of oil and coolant for some reason but is otherwise reliable.

Along the way we dropped in at the Williamtown Fighter World which I can recommend as an excellent display of military planes near the base. From time to time jets fly over and it can be quite a display.

Here's Peter with a type of fighter that once took a shot at him:


There are two large sheds full of planes, trainers, and even some missiles.


And who could resist the attractive observation deck so beautifully promoted in the flyer:


While exiting through the gift shop, I bought this excellent key ring tag for the van:


After Williamtown, we dropped in on another ABC alumni, the venerable Tim Bowden, who was in fine form.


Tim is an experienced camper who has advised me on various aspects of the van. He was more than happy to try it out.


The stay at Dorrigo was again relaxing and entertaining. It's a place that has very high rainfall but at the moment even it looks a bit dry. I'm sure the federal minister for climate change is working on the big dry and planning for our carbon reduction as a top priority of government...

Thursday, July 26, 2018

Built a QCX 20m kit

Inspired by the fascinating talk by Hans Summers I mentioned recently, I ordered a QCX transceiver kit with filter for 20m. Hans criticised the continued use of the obsolete NE602 based QRP transceiver design in the light of more modern and better performing quadrature detectors based on clever programming of the Si5351 clock generator.

QRP Labs, Hans' company has published an excellent paper that accompanies that talk. For US$49 you get amazing value.

The quadrature sampling detector is shown here (reproduced from the paper which is well worth a thorough read). Here's the full circuit.



The board has the surface mount ICs already soldered as you see above and the components are neatly bagged up.


My kit was missing the plastic screws which is no big deal.

My board was revision 4 and unfortunately the assembly manual hasn't been updated yet. The instructions are very clear and detailed. I mis-installed a few resistors, completely my fault, but easy to do. Colour codes are hard to read sometimes.

The most challenging part of the build is the T1 Toroid transformer with 4 windings but Hans has included a diagram from a third party that makes it quite clear.


The software is fantastic with a menu driven system that includes built-in alignment circuitry that is magical! With no antenna connected, test signals are generated and measured with multi-range bar graphs so that the front end band pass filter can be peaked, I-Q balanced, and 90-degree phase shift can be adjusted for high and low frequencies. (Note that these last three interact so you have to rock between them to optimise).

I'm getting about 4W out on 20m with a 13.8V supply.


The RF out stage is three BS170 FETs running in class E and it's amazing to see a few small transistors producing this power without excessive heating.

I enjoyed building this kit, it's great value, but care is needed as it's quite difficult to remove components from the dense board.

Today was the ARNSW home brew group meeting. I passed the QCX around along with the circuit diagram which attracted quite a bit of interest.


Tuning around 20m this afternoon I found the CW decoder works amazingly well. This is a 200Hz bandwidth CW receiver but I'm able to listen to SSB, although it's rather too narrow. I hope QRP-Labs does go on to make an SSB unit based on a similar design.

Wednesday, July 18, 2018

A visit to the home of FreeDV and codec2

Arriving in Adelaide after the spectacular Great Ocean Road, David, VK5DGR, was kind enough to invite me to stay with him. I knew I was in the right place when the squid pole supporting a corner dipole came in to view.


I was very keen to see where the "magic" happens concerning the development of the world class low bit rate voice codec2 and FreeDV. While David insists that much of it is done on a couch with an old ThinkPad he does have a nice bedroom setup with some test gear.


Two members of the influential Amateur Radio Experimenters group, Mark, VK5QI and Matt, VK5ZM came for dinner and we had an entertaining chat about balloon telemetry and tracking. Mark brought along one of the radio transmitters harvested from those launched by the BOM.


These folks are known internationally for their work launching balloons and tracking them. It was great to meet. David, has contributed an improvement to the radio modem software that is used to transmit telemetry.

At the moment, David is working on a new mode called 2200 for FreeDV with better quality (and a higher bit rate than 700D) and I was pressed into service doing a field test where we left a test transmission running and drove several kilometres away to receive off air and measure real world errors. We met up with Peter, VK5APR at the park. I haven't seen an Alexloop up close before and was impressed with how well it worked.


The tests went well and it was interesting to see how the spectrum looked flatter on my KX3 than it did on an FT817 (where is slopes down to the right).


David has a much better and more technical blog post on the development and field testing.

Vanlife on the Great Ocean Road

The main attraction of my current trip has been the drive along the Great Ocean Road from about Geelong over towards Adelaide.


The road is spectacular with lovely spots to stop and walk to see views like the one above. There are lots of tourists and apparently they need to be reminded of the road rules quite often.


The van is running well again but I heard a strange clunking sound which I thought was something falling in the back but turned out to be the right front indicator.


I have repaired this with duct tape but will get it fixed on my return. I can see it's been glued up by past owners.

Van tour of ham shacks

In my current van expedition I've been dropping in to a few ham radio friends. On my way south I visited Peter, VK3RV, who I met on the Sunday FreeDV callback. He has a terrific signal from his QTH in Sunbury in to my location in Sydney. He's on a property and has a nice HF antenna setup.


While there we had a contact with New Zealand using the amazing FreeDV 700D mode.


Thanks Peter for the hospitality and fascinating chat.

Monday, July 09, 2018

Van broke down

It's an old van and so far I've replaced the differential, rear bearings, battery and tyres. Yesterday I was rather lost on muddy logging roads with no mobile reception and I noticed that sometimes the van didn't start first time when I turned the key.

Today I stopped at BCF just out of Wagga Wagga and when I turned the key... nothing.


Because it's an old van I decided to join the NRMA and today I took advantage of that with their roadside assist service.


In these Hiace vans the engine is under the passenger seat. The technician seemed ready for a battery replacement but my volt meter showed me that the battery was fine. The starter motor is underneath and a rap with a hammer and it worked! The guy explained that this is a common short term fix but in the end the problem will re-occur.

I've had the starter motor replaced for $380 (with member discount) and I'm pretty happy with that. They fixed it same day but I'm staying over in a motel. Hitting the road again in the morning.

I feel very fortunate to have broken down in a town rather than up a muddy, rarely used track, with no mobile reception. A close call.

A toilet for the van

I must admit I've been hesitant about this, but touring around in a camper van wondering anxiously about where the next toilet will be found was distracting me.

As mentioned in a previous post, I've been peeing in a bottle to avoid going outside in the middle of the night. Before heading off on the current adventure, I bit the bullet and purchased a small chemical toilet for about $160.

Also purchased was the recommended flush water additive, collection chamber additive and special toilet paper that breaks down fast. I'm advised by camping expert Tim Bowden that the flush additive isn't required and that Napisan can be used in the sewerage chamber.

Currently I'm camping alone so have no qualms about using the thing in the van with the curtains drawn and door locked, not sure how I'll go with my wife on board. Some people use a popup lightweight tent to make a separate outdoor toilet.

It's great to be able to camp at free sites with no facilities such as this spot near Gundagai near the river.


While my ultimate plan is to avoid using the ensuite if possible I was kind of keen to try it just to see how the process works and how nasty it might get. After a few days, and depositing of both number 1 and 2, I looked on the WikiCamps app for the nearest "dump point".


Dump points are fairly common it turns out. Under the lid there's a giant funnel. Next to it is a tap and hose. I wore rubber gloves but found the dumping of the cassette pretty easy and clean. The additive chemical seems to be a strong perfume so there were no unfortunate smells.

After dumping I filled the cassette with water and shook it, then rinsed it out. I did this twice and all seemed reasonably clean.

We forget the magic that city sewerage systems perform. Camping out, using drop or chemical toilets is a reminder of the reality of all this.

Sunday, July 08, 2018

VK1UN's nifty FL2K filters

Ross, VK1UN, has built a nifty interface from the FL2K VGA dongle to some low pass filters for transmitting WSPR, he writes:

I’ve gone ahead and put together what I have in mind for the VGA cable with R/G/B out.

I was thinking that, if I am running output to Banana terminals for wire antennas, I would just design 75 Ohm filters to hard connect inside the little Aluminium box between the 3 RCA socket block and Bananas. See the first pic. It is going ahead smoothly despite requiring quite a bit of accurate hole drilling and hole matching with the 3 RCA socket board.I think it will be very neat.

Secondly, I have designed three Constant K 750 Ohm filters that are dual band:

60m & 40m, 30m & 20m and 17m & 12m. Whilst I have not built these all yet, I have modelled them on LTSpice and they look to have very suitable performance and all are using standard component values or a minimum combination thereof.

Here's the box showing how the VGA connector to RCA lead is used.




 30m and 20m LPF
75 Ohm, 17 and 12m
75 Ohm 60 and 40m

I’m stopping at 12m now as I am not sure of the wave from a 17m or 12m Weaver generation, but the multiples of 48K, QRG and Sample rate seem to be close.

You can contact Ross at any of the following callsigns @amsat.org: VK1UN, VK8UN, 6O0O, T61AA, EX1UN.