Sunday, December 21, 2014

Copper pipe loop for 40m

Inspired by the work of Peter, VK3YE, I visited the local hardware store to get bits for a 40m loop antenna. Purchased a 3m length of copper pipe, some hose clamps, some copper saddles, a piece of dowel, and a plank of wood. Here's the result:


The variable capacitor is clearly not going to be able to stand much power but at 20W it doesn't appear to be arcing. This capacitor has a reduction drive and I'm using a switch to add a bank so that I can tune both 40m and 20m. Joining the tuning shaft to a dowel rod with a piece of plastic pipe and cable ties worked out quite well although there's a little slippage.


Matching stub:



Tuning is incredibly sharp but a very low SWR is achievable.


The offset of the tuning stub was a guess but seems to be reasonably close to 50 ohms. I had a pre-arranged contact with Stephen, VK2BLQ who could hear me reasonably well.

Reception seems excellent and of course the very narrow bandwidth leads to nice low noise.

Friday, December 12, 2014

Built an Ultimate3 Beacon

This week an Ultimate3 QRSS/WSPR kit beacon kit I ordered arrived and this morning it was easily built.

The display is super crisp.



I ordered mine with the 30m low pass filter.


The whole thing runs on 5V so I chopped an old USB cable and have been running it from a USB charger or battery.

It's a great kit, with very clear instructions and it came together very smoothly. Mine was missing one small capacitor but it was no trouble finding one in the shack.

The software is very well done and everything is set up using two push buttons placed in just the right spot for your fingers while holding the board with the display facing you.

Amazingly this does WSPR as well as lots of modes:

- QRSS mode (plain on/off keyed slow CW)
- FSK/CW mode (frequency shift keyed slow CW)
- DFCW mode (dual frequency CW)
- WSPR mode (Weak Signal Propagation Reporter)
- WSPR-15 experimental WSPR mode with 15-minute frames
- Opera modes (8 speeds)
- PI4 beacon mode
- Slow-Hellschreiber (frequency shifted slow-Hell)
- Full-speed Hellshreiber
- Half-speed ("DX") Hellshreiber
- CW (plain CW)
- FSK (0-999Hz shift, fast-speed FSK CW)
- Customisable FSK patterns
- manually-keyed CW/FSK transmitter

I ran Hellshreiber for a while but it didn't look too good on fldigi in the house, now I'm running 20WPM morse but that's not decoding perfectly either - my guess is that the signal is so strong that AGC is messing with it but I'm still trying to figure this out.

Sunday, December 07, 2014

Useful M8 transistor tester

I purchased a transistor tester kit from AliExpress a few weeks ago and it's a useful gadget for the workbench.

Often when home brew circuits haven't worked it has turned out to be because I didn't get the pinouts on transistors right and this device figures out the EBC pinouts of a given transistor. It also analyses other components although not small values.


Cost about $25 landed.

Tuesday, December 02, 2014

Digital voice ove HF radio talk

This week the ARNSW Home Brew Group was honoured with a visit from David Rowe, VK2DGR, who spoke about codec2, FreeDV, and the upcoming hardware implementation called the SM1000.


Friday, November 28, 2014

Install freedv on Ubuntu 14.10

Just a note for others who might run in to the same issue. Freedv depends on libtiff4 which is not available for Ubuntu 14.10. Here's how to install freedv and avoid that bump in the road.

# grab the library from an old version of ubuntu
wget http://mirrors.kernel.org/ubuntu/pool/universe/t/tiff3/libtiff4_3.9.7-2ubuntu1_amd64.deb
sudo dpkg -i libtiff4_3.9.7-2ubuntu1_amd64.deb

sudo nano /etc/apt/sources.list
# add these lines to /etc/apt/sources.list
deb http://files.freedv.org/debian/ stable main
deb-src http://files.freedv.org/debian/ stable main

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install freedv

Now you'll find the app if you search from the dock.

Thursday, November 06, 2014

New version of WSPR Watch for iOS is out

I've updated the iOS app WSPR Watch with support for iPad, iPhone 6 and 6+.


The program is simpler than before but I think more useful with a feature I've long wanted, a direct view of how long ago each of the spots were reported.

As always, it's free and all data is gratefully pulled from the legacy database page on wsprnet.org.

I'm happy to report that there are a couple of equivalents for Android, one from developer Derek G4SWY, who made WSPR World Watch, and another called WsprNetViewer by Joseph D. Glandorf with source code and it's in the Play store. Great work!

My own WSPR beacon station is on 20m running a vertical wire antenna on a 6m squid pole. It doesn't take much to reach around the globe.


Saturday, November 01, 2014

wspr on Ubuntu 14.10

The easy solution

Thanks to this post, from Greg, K17MT, here's what you do.

sudo add-apt-repository ppa:ki7mt/wspr
# press enter when asked something
sudo apt-get update
sudo apt-get install wspr ntp

Now you can use the Ubuntu launcher to launch wspr, or as I did, drag the icon to the side dock and launch.

Note that I also recommend installing the ntp time sync service as I find my ubuntu laptop clock drifts off and by default Ubuntu only syncs the clock on each boot.

Watch out for me, vk2tpm, on 20m.

Thanks Greg!

Obsolete below here

Building WSPR on linux is often a bit of a puzzle. With the help of the clearly very clever George Smart M1GEO I got most of the way.

He didn't draw a lot of attention to it, but after running ./autogen.sh you do need to edit the Makefile and change /usr/bin/f2py to /usr/bin/f2py3.4

After successful make and make install, running wspr gave me a python exception ending in ImportError: cannot import name '_imagingtk'

The solution is:

sudo apt-get install tk8.5-dev tcl8.5-dev
sudo pip3 install -I pillow

It's now running although I now get a crash shortly after it starts decoding.


So audio in is working. My guess is something is wrong with the fortran to python interface. Any tips would be most welcome.