Friday, December 08, 2023

WSPRnet down with database error

Users of my WSPR Watch app have been reporting problems over the last day. It looks like is down with a database error. "PDOException: SQLSTATE[HY000] [1040] Too many connections in lock_may_be_available (line 167 of /data/var/www/drupal-7.98/includes/"

Unfortunately, my error handling code is looking for a connection error but is failing to pick this up and fails silently as if there's no new data.

WSPRnet handles a huge amount of traffic and I hope they're able to fix this soon.

Wednesday, December 06, 2023

Talking tech on ABC Radio

Another chat with Philip Clark last night on ABC Radio across Australia. If you like, you can listen here.

I've purchased a new microphone, a Sennheiser Profile USB. Frequency response is mostly flat but it has a nice peak in the high frequency which I think makes it sound clear.

Knobs on the front make it easy to set mic gain, headphone level and the mix between return audio and local foldback. There is a quiet to operate mute button.

The era of USB-C is giving me an excuse to upgrade many things.

Tuesday, December 05, 2023

Five acres and antenna bliss

After a life in dense suburban settings where HF reception is poor, I am enjoying the benefits of five acres in the bush. 

The radio shack is in a shed somewhat distant from the main house (which does generate a bit of HF noise). 

Happily there is a convenient dead tree next to the shed that I use to support my antennas. Other trees hold the ends of dipoles up.

Getting lines up over these branches has been done in several ways, including a long squid pole skilfully wielded by Dallas, VK3EB, but the current method is a (rather beaten up) drone.

I tie a line around the drone, fly it up over the branch or tree top and then hit the motor kill switch. The drone falls, pulling the line as it goes.

This is very reliable and so far hasn't damaged the drone too much. It's a repeatable method but only one of my drones can be commanded to kill the motor without complaining.

There's a port on the wall of the shed where I have SO-239 through connectors. I have experienced quite a bit of frustration when an antenna stops working. I check the coax, the patch cord inside the shed, the balun and in the end the problems have been the through connectors.

The left connector, from China, is very unreliable. The centre pin disconnects. The middle one seems better and the right hand one is the best.

They don't fail without some trauma and in my case my coax has been attacked by birds or, more dramatically, by a kangaroo getting tangled up and ripping the coax from the connectors. To avoid this somewhat, I've run coax through some PVC pipe.

The current configuration is separate dipoles for each of 80m, 40m, 20m and 10m with a switch on the wall.

Also there is a vertical wire going to the top of the tree and a ground stake. This is used for general reception on SDRs. With a little extra length or inductive load it would also tune up on 40m.

I'm happy with the configuration here and am considering a horizontal loop as an interesting comparison.

Wednesday, November 22, 2023

Adapting Ozito battery for ham radio power

We have quite a few low cost Ozito (Bunnings) battery powered tools around here even though I've been transitioning to Makita. The battery packs put out about 20V when fully charged which is too much for nominal 12V radios. I purchased a variable buck converter that can regulate this voltage down. 

To get power from an Ozito battery I butchered a spare single battery charger with pins like this:

Internally, there's quite a bit of circuitry - a bit surprising considering the low cost. The metal pins are soldered right through the board so rather than trying to remove the board I just clipped the power input and soldered on to the back of the battery + and - pads:

A few cables later and we were up and running receiving FT8:

Regrettably, the buck converter produces noticeable noise peaks on the waterfall:

Threading the output DC cable through a toroid improved things quite a bit:

The spectrum looks much better although there is room for improvement:

Credit to VK3KR, David, for the inspiration for this project.

Talking tech on ABC Radio

After contributing technology commentary for many years on ABC radio, I've had a break this year but now I'm back. This week I did a spot with Philip Clark on ABC local radio's Night Life program.

You can stream it here.

ABC Radio Sydney is turning 100 about now although NightLife is a national program.

It looks like I'll be a regular contributor to the program presented by Philip Clark.

Sunday, November 12, 2023

Rosebud Radiofest excellent again this year

Like 12 months ago, I joined Richard, VK3LRJ in the journey down to the Rosebud Radiofest.

It seemed bigger than last year. Certainly there was lots of great gear on sale.

Even Ralph, VK3ZZC, was tempted with some exotic equipment.

I came away with just one item. A rather mysterious Ten-Tec "Energy Amplifier":

It turned out to be what I had hoped - a nice little amplifier with decent speaker in a box. Very handy for monitoring projects on the workbench. It was missing a screw but on disassembly it was found stuck to the speaker magnet.

There were wonderful antique radios on display again this year.

Like last year it was a very well organised event with lots to see. I was tempted by quite a few items but managed to hold back. Great to catch up with a few friends.

Friday, November 10, 2023

FreeDV 700e contact with VK3RV

It's been a while since I've fired up FreeDV. For some reason there isn't a pre-made build for Linux so I grabbed the source code and simply followed the instructions to build it (really just a few dependencies and the build script does the rest).

The user interface looks nicer and there's a better initial setup dialog that makes it easier than when I last tried it. Peter, VK3RV, (who incidentally I first met on FreeDV), was kind enough to have a contact with me.

We first talked on 700e, then tried 1200 and finally 2200. Each sounded better although Peter couldn't copy me on 2200 but it looks like he had some local interference which was pretty severe:

Amazing he could hear me at all with that going on! His screen shot reminded me that you can have several of the visualisations showing at once. It's not obvious how to do this but the trick is to drag the additional tabs up and a bit to the left, until you see an area highlighting, then drop.

A terrific innovation is the new FreeDV reporter window which shows who's on and what frequency and mode they're set to:

FreeDV is looking better than ever and I know David, VK5DR, has received some funding to support additional work on the project.

Sunday, October 15, 2023

Latest OpenWebRX on Raspberry Pi 4 excellent

With a little travel on the agenda soon, I thought I'd run up OpenWebRX on a Raspberry Pi 4 in the shack.

The simplest approach is to download the pre-made SD Card image and boot from that.

The "whistlers" I've been seeing on 10m are less today than they were.

Getting started with OpenWebRX using the Pi image is a bit mysterious. There is a setup guide but I couldn't figure out how to log in. They say:

"The default user "pi" no longer exists. Please use the included agent"

What is the "included agent"?

My Pi is headless so to get it on the Wifi network here I had to use the Raspberry Pi imager which let me set a user and password and configure the Wifi.

Once logged in over ssh I created an admin user for OpenWebRX with:

sudo openwebrx admin adduser adminusername

If I edit the /var/lib/openwebrx/settings.json file directly, I found that it would be overwritten unless I forced a restart of openwebrx with:

sudo systemctl restart openwebrx 

Anyway, all good in the end. It works very well on a Raspberry Pi 4 and it's great to have FreeDV, M17 and DMR all built right in.