Sunday, May 30, 2021

Wonderful new SDR design described by Ashhar Farhan

A video of a presentation by Ashhar Farhan, VU2ESE, has been posted and I can't recommend it highly enough. He describes a new design for what looks to be an easy to build SDR based around a Raspberry Pi. Along the way, Ashhar also clearly explains many of the key parts of how a Software Defined Radio works.

The paper that goes with it can be viewed here. Thanks to Stephen, VK2BLQ, for drawing my attention to this and for Bill at Soldersmoke for the link.

Today is a bit sad for me as I'd hoped to be going to MayHam at Wyong but due to a pandemic lockdown in Melbourne I'm unable to leave my home.

Friday, May 21, 2021

A visit to Paul Taylor, VK3HN.

I have been a fan of Melbourne ham radio home brewer Paul, VK3HN's blog and YouTube channel for some time. We met a few years ago at Peter, VK3YE's QRP by the Bay but I discovered that he lives not too far from my new home in Thornbury so I invited myself over for a visit.

Paul's blog is of a very high standard, well written, with extensive technical information about his projects. In recent years, projects have been demonstrated and explained with well made videos as well.

Projects cover the spectrum from small portable CW rigs all the way to a high power AM transmitter using the efficient Class E mode.

There's a few things that stand out to my eye - Paul tackles complex projects with a logical modular approach, often building on tried and tested standard designs but without fear of trying more challenging designs. 

Circuit boards are manually etched using the resist pen method.

Most striking of all are the cases which are custom fabricated from aluminium angle stock and sized to snugly fit the enclosed circuitry.

Thanks Paul for an entertaining and educational evening tour of the shack.

Incidentally, you can hear more from Paul at HRDX via SolderSmoke and a terrific interview on QSO Today episode 298.

Sunday, May 16, 2021

Low cost loop antenna for 40m from VK2BLQ

Stephen, VK2BLQ, and I test the Sydney - Melbourne path using WSPR and we have been comparing our noisy external antennas with loops in various positions. 

Today he sent details of his latest loop made mostly with bits of Bunnings.

He writes: "The loop is approx. 900 mm diameter as it was a 3m coil of copper from Bunnings, when it was cheap.

I let it run on 40 m wspr yesterday and this morning and pretty much was only received along the east coast but not by Peter. Only the wire antenna which is 3 m above the loop reached USA Canada and all over other places.

WSPR is ok but the only real test is for two way communications; I could hear VK3XU at good  level this morning and VK2ARZ a bit later. I need a small changeover switch between keyer and key.

The tuning capacitance is the double sided pcb, the actual value of capacitance depends on the thickness and type of the fibreglass, so it was a case of measuring a piece and cutting off small pieces until I can see the minimum swr on a Nano VNA. The PCB has a coat of lacquer and soldered to the loop, it probably is not too resilient outside.

The Coupling loop is a 1 m length of RG 11 75 ohm TV cable with only the braid and foil shield being used. It is longer than the customary 20 %, and perhaps that is why the Q is low.

Some heat shrink to cover the joints and definitely only temporary.

Next version will be a 6 m perimeter octagon as I have four 1.5 m lengths of copper. I read somewhere that the capacitor should be at the bottom with the feedpoint at the top for a better angle of radiation. This is possible if I re-solder the PCB capacitor".

Stephen is certainly covering Australia on 40m WSPR but oddly missing the bit of Melbourne where I am located.

We are travelling to MayHam at the end of the month and if it fits in the car we'll bring it along for the Home Brew display.

Sunday, May 09, 2021

Attended a rally in support of the ABC

Josh Frydenberg, Federal Treasurer, did not attend the meeting at Hawthorn Town Hall - despite a respectful invitation - but about 450 people did. A letter from Mr Frydenberg was read in full to the assembled audience prompting some laughter and astonishment as he repeated the Coalition’s position that there have been no cuts to the ABC while also arguing that all media hurting and so should the ABC.

Speakers at the evening included ABC Friends’ President Michael Henry; past Chair of the ABC Advisory Council and Director of the Victorian College of the Arts, Professor Andrea Hull; Professor Ed Davis AM; Vice President of the Media Entertainment and Arts Alliance, former ABC journalist, Karen Percy; and Former ABC journalist and ABC Alumni member Jim Middleton.

Tosca Lloyd showed a film produced by GetUp titled “Murdoch and Morrison vs the ABC” which drew together the broad community support for the ABC and illustrated the concerted campaign by Murdoch media and the Institute of Public Affairs (IPA) to weaken or even privatise the ABC.

The panel discussed the impact of cuts to the ABC experienced so far including cuts to key programs and staff levels during the government’s time in office. More subtle attacks on the ABC including efficiency reviews and frequent criticism of program makers in Murdoch media were also discussed.

A video of the event is available.

It was a very professional, focussed and well-run event. It was my pleasure to work in a small way with Michael Henry and in particular key organiser Marcus May in the preparation of the event. My thanks to Jim Middleton for stepping up to speak and be on the panel.

Friday, May 07, 2021

Talking crypto on the Vertical Hold podcast

It was my pleasure to be a guest again on the Vertical Hold podcast this week. 

In this week's episode: "What’s the tech behind BitCoin’s booming rivals like Ethereum? What are ‘smart contracts’? Why would you build an AI bot and give it dementia? Guests Access Informatics’ Peter Marks and Dementia Australia CEO Maree McCabe".

Hosts Adam Turner and Alex Kidman run a tight ship and it was fun for me to experience Zencastr for the recording which records each guest locally in high fidelity and then uploads their audio. 

Monday, May 03, 2021

Got the first AstraZeneca Vaccine at Melbourne Exhibition Centre

Today I became eligible for a COVID vaccine so I was keen to get it done. The web site indicated that my closes mass vaccination centre is the Melbourne Exhibition centre. The site said I could book an appointment or just turn up and there was a 15 minute wait. I decided to be a "walk-in".

Arriving at the address, I could see the building but no visible signs or people. There are some signs but they are on the ground.

It turned out that the entrance was on the side opposite the Museum.

The queue was short but slow moving. There was no sign to confirm what the queue actually was. A bloke in the queue before me joked that he was here for the beer festival (which was on the last time he was here). After a while staff came out and asked for people who had booked to come out and go straight in, even if their appointment was hours in the future. 

At the door we were temperature checked and given masks.

Once inside, there are more queues. We were advised to have our Medicare card handy.

At the desk we were also asked for photo ID so people had to dig through their purses and wallets.

After the interview we were then directed to a mysterious system of rows of spaced chairs, then on to a single row of chairs and finally to a booth with a person to give the "jab". 

The injection was completely painless for me. Next jab is due in 12 weeks, you can go as early as 4 weeks but 12 weeks is better.

After the jab you sit for 15 minutes before leaving. All staff I interacted with were efficient and professional.

Lessons for consumers:

  • Booking is a fast track to the door
  • Bring your Medicare card and photo ID
  • Bring information on any medications you might be on such as blood thinners
Suggestions for the vaccination centre:
  • Put up a big sign at the address you give directing people to the queues
  • Have signs on the queues saying what they are: "walk-in" vs "appointment"
  • Tell people they need to have Medicare and photo ID ready
Side effects

My arm started feeling warm almost immediately. A few hours later it's a little sore and I have soreness under my arm. One day after the first jab I felt general muscle soreness. Took paracetamol. Felt very tired and had a sleep for a few hours in the afternoon. Day two, arm still sore but no other discomfort.

Saturday, May 01, 2021

Forced to wait over four hours to get through to Qantas to use a credit

A flight I booked last year with Qantas was cancelled by them due to pandemic lock-down and so I have a credit. Now that things are open again I wish to use that credit. It's not easy... The web site told me I had to ring them.

I've rung a few times in recent months and been informed that the wait time was over two hours so I gave up. Today I decided to stick it out as it didn't give any information about the wait time. I interpreted this lack of estimate as a sign that it was going to be quick.

After more than two hours I started trying to contact them via Twitter as this seems to have worked for some other people in my situation.

Facebook looked like it might be a more efficient way to contact them as they say this:

Alas, "7 days" doesn't seem to include today.

I tweeted a thread of comments but didn't get a response. 

This is what you have to listen to:

Finally, after more than four hours I got to Eric. A very nice operator who was able to fix me up.

I value my time and this punched a big hole in my day. My guess is that many people are not able to invest this much time in redeeming their flight credit so Qantas gets to keep it. This reeks of being a "dark pattern".