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.

Update

Had a visit from Bob Bray who liked both the shed and the loop antenna, although I suspect he wasn't impressed with my impression of a circle.

Robert John Bray is a prominent astronomer who has been honoured by having a main belt asteroid named after him.

Update - motor drive tuning

I've changed capacitors and added a 36RPM motor drive and a box to switch direction. The drive is still way to fast and now I'm looking for a reduction gear or multi-turn capacitor of some sort.

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.

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.

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.

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.

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.

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.

Another hobby - Quadcopters

Accidentally purchased a little quadcopter and then found that the expensive ones have come down in price since I last looked. These videos look much better on YouTube at 720p full screen.

You can see my 20m vertical on a squid pole on the balcony at the front. It's running my WSPR station.

I bought a Quattro-X which can easily lift a camera and has the advantage of GPS stabilisation so it's not too hard to control even when there's wind. A surplus of trees does lead to some messy landings however.

The quadcopter is getting pretty beaten up.

Back home, back on lower bands

For the past eight months we've been living in an apartment and while I enjoyed learning about antennas on a balcony, it's good to be back at the normal QTH. The neighbours behind us have a magnificent gum tree which supports my new 80 and 40m dipoles.

You can't see the thin wires so hopefully it won't annoy the neighbours too much. I don't really have enough space for the 80m dipole which runs along the side fences, but 40m works really well and tunes up beautifully.

It's good to be back and while I have lots of unpacking and re-organising to do my hope is that ham radio projects will again get some time.

iPad version of WSPR Watch coming

Here's a sneak peak:

It updates itself every few minutes but I am concerned about loading wsprnet.org too much.

New transceiver for the shack - with valves!

Great day at Dural today. Particularly impressed with the home brew moving coil compass built for a model boat. I didn't mean to but ended up walking away with a beautiful Yaesu FT-101E for $200.

Had a contact with Stephen, VK2BLQ, who reports that I sound normal so that's all good. Plate and Load knobs are new to me but fun to learn about.

For my younger readers, this is what a valve looks like:

The compass was fascinating, it uses a spinning coil with an amplifier in the centre. Power is fed in through the ball bearings and the output is sent by an LED light.

We turned it on and compared with a compass in a smartphone.

A wonderful device, but I think technology may have moved on.

Update

Here's a video of what it's like to tune across 20m on the FT-101E back in the flat with a dipole on the balcony.


We're moving out of the unit back to the normal QTH in a few weeks so I thought I'd capture this for future reference.

Appearance on RN's Download this Show

A busy week, media wise. I was on RN's Download this Show:


Also wrote an opinion piece about how the BitTorrent technology can be used for good as well as evil, published by the ABC.

What's cheaper than a Raspberry Pi and runs linux well?

I'm interested in playing with some of the new virtualisation technologies, such as docker. For this stuff my usual go to toy, the Raspberry Pi doesn't quite cut it. This morning I spotted a Dell Optiplex PC, Core 2 Duo 2.5GHz, 2G Ram, 250GB disk for $35 on eBay with no bids.

Ending an auction at 7:15am on Sunday morning may not be the best way to sell technology.

So far I've installed the 64bit version of Ubuntu Server 14.04 and following the instructions from the excellent Ubuntu documentation created a virtual machine in which I've installed another copy of the Ubuntu Server.

This works magically, the qemu environment can be set up to share the virtual console via VNC and from my desktop machine I answer the install prompts as if sitting at an actual machine. Here's how it looks:

Now I can safely try all sorts of crazy things in this virtual server and just delete anything I'm not happy with.

Here's the giant new server (with a Raspberry Pi next to it for scale):

There are bargains out there, but I should say that this was a crazy price. You can pick up similar systems for under $200 pretty easily though.

Balun day at Amateur Radio NSW

Today was "balun day" which began with breakfast followed by a terrific talk from Mark, VK2XOF, about the theory and practice of building current baluns. The biggest mystery for me is what core to use.

After the theory, and lunch, we all received out balun kits from TET-Emtron. I went for the TB-11K 1:1 kit rated at 1kW peak. We then built our kits under the guidance of folks who had built them before.

Finally there was a spectrum analyser and antenna analyser on hand to measure the baluns. Some home constructed baluns were found to have high reflected power which was very interesting to see.

The method for assessing a balanced to unbalanced balun's operation is to attach a 50 ohm load on to the antenna terminals, feed it from an antenna analyser and connect one and then the other of the antenna terminals to the ground of the input and see if the impedance changes very much - if all is working well it should not change.

My sincere thanks to the ARNSW committee and all who clearly worked hard to make this day a great success. Thanks also to TET-Emtron for producing the fantastic kits and for their support.

Windy in Sydney this afternoon

Up here on the 28th floor it was pretty windy today. The doppler wind radar looked pretty interesting. RNDSUP seems like a fun technology.

ABC Download This Show appearance - Chromecast, Upworthy, Unicode

We're videoing radio again this week. Here we are in the Radio National studio talking about technology.




Exciting news for people who like watching radio programs on video - Download This Show is now available on ABC iview. (Search for it or look in the iview channel).

DDS VFO purchase

I recently purchased an old crystal controlled Codan lunchbox radio and want to put it on 40 and 80m so I've found a rather nice DDS VFO on ebay for AU$45. This one has two PIC CPUs on the board, a nice backlit display and comes with a tuning knob but no info on wiring it up.

The same unit is in other ebay auctions and one of them has this "schematic" which will be a help, if it's correct.

My board came with some cables with sockets to match the connectors on the board and the rotary encoder. Here's other info, for future reference. (It all seems a little mysterious to me but hopefully will be clear when I play around with it).

Note that the wiring of the rotary encoder in the sketch above (from an eBay ad) is shown from the rear of the encoder. I wired it up in reverse and it works but the tuning goes clockwise for up in frequency.

My thanks to Stephen VK2BLQ for access to his workshop, here's my VFO all boxed up.

One criticism of these boards is the lack of mounting holes. I've stuffed the box with cloth to press it against the front and that works fine but is not ideal.

I've now added a 9V three terminal regulator so that the unit can run from my 12V bench supply.

All up this is a terrific VFO, pushing while turning the knob changes the digit that will be adjusted so it's quick to get around. Thanks to commenter Yiannis, the documentation and software source has been traced to Ham Radio India.

The objective of this device for me was to use it as a VFO for my Codan 6924 radio. There's a handy page outlining how to do this. This weekend I ran a cable to an empty crystal spot.

This makes the old radio look very fancy.

As I tune around I notice carriers sweeping by at some frequency ranges but not others. I took the DDS over to VK2BLQ's lab and it seems that for many frequency ranges the output drops dramatically. I'm not sure what's going on here but my guess is that it's designed to cover only certain bands and not others.

Report from WWDC for Download This Show

Australian broadband needs upload speed too

I'm in San Francisco this week for the Apple WWDC. The flat I'm sharing has apparently typical broadband. It certainly seems very snappy for downloads but what absolutely kills me when I compare what we have in Australia is the upload speed.

This is over Wifi by the way. At home on Telstra I get 100Mbps down but around 2Mbps up. This makes sending files or backing up to the cloud very difficult. Will the NBN fix this?

I asked the other residents of the unit if their internet connection was typical, amusingly they took this as a complaint and apologised for the poor speeds and asked if I was having trouble. They expect to get 100 down and 50 up. There is no download limit. They pay $400 a year.

Update

I'm currently in San Francisco at the Apple developer's conference and here we have the fastest internet I've experienced so far.

This is not some science fiction future world, this is today.

Noise in flats

This appeared in the lift last week.

Most interesting. I'll have to avoid raucous laughter and talking over other people.