Tuesday, March 20, 2018

First stage of the Great North Walk

The Great North Walk is a well known track starting in Sydney and going, you guessed it, North. Peter, VK2EMU, mentioned that he was planning to start it and I was keen to join him.

The whole walk is over 250km in sections that end up in Newcastle.

We did the first section, beginning at "The obelisk" in Sydney city, near circular quay and ending near Chatswood.

While there is some walking through leafy Sydney streets the best bits in this section were the surprising wetlands around the harbour.

We walked for about five hours and while it's not a hard walk I was pretty tired at the end of it.

Thanks to Peter for taking me along and I look forward to doing more parts of it in the future.

The marker where it kicks off:

Most of the walk is well sign posted like this (although we took a few wrong turns along the way).

I love how they show how far to Newcastle on signs.

There's some lovely bush to enjoy.

US Military vastly outspends opponents on radio gear

At the Wyong field day this year I bought a book on the history of military radio. An entertaining read although the author covers the history of wars and radio along the way.

Ars Technica has an interesting piece about US army radio which has chosen a hard technical path requiring the use of CORBA software interfaces in radio software.

This seems particularly amusing in the light of all those images we've seen of non-american combatants using Icom and more recently Baufeng radios which cost tens of dollars each instead of hundreds of thousands of dollars each.

How does the US pay for all of their extravagent military expense?

Saturday, March 17, 2018

Enjoyed the John Moyle field day

Today, and tonight, is the annual John Moyle field day which encourages portable operation from portable power. Peter, VK2EMU, kindly invited me to join the team from the St George Amateur Radio Society who had arranged a wonderful location at Oakdale, west of Sydney.

The gang had a veritable antenna farm with everything from 160m up to UHF. I was planning to just use the 20m vertical on the van but Con, VK2FCDL had a new off centre fed dipole that he was keen to try out of China. It's called a BG7PNV HF20A Dipole and it tuned up beautifully on both 20m and 40m. It claims to work with low SWR from 500KHz up to 30MHz and while I can't vouch for that, we had contacts on 20 and 40m. There is a big resistor in line very near the end of the long leg, perhaps that keeps the SWR low?

It was a warm day but with a very pleasant breeze.

Tuesday, March 06, 2018

Vanlife: a quick trip to low noise land

Last week I had a quick trip north and camped near the Wallamba river near Failford before heading off to Black Head to visit Patrick, VK2PN and Heidi.

I purchased a whip for 20m from Stephen, VK2BLQ, and took the opportunity to compare reception with the end fed wire I've been using.

To my surprise, signals were much stronger, perhaps 2 S points, on the vertical. Presumably the van makes an excellent ground plane. You can see the whip on a small magnetic base in the photo here. The base is too weak for driving while attached.

Here's some video of a tune around on 20m. Nice low noise and strong signals.

Sleeping by the river meant dealing with a few mosquitos. Happily I have a net which I hung over the bed with magnets - a system which worked well. There is a benefit to having a van made of steel rather than an aluminium caravan.

Common fault with boxed RTL-SDR devices

I have one of these boxed up RTL-SDR devices that has a low pass filter and the modification for direct sampling for HF. They work pretty well. Mine stopped working recently. When plugged in to USB the power light comes on but the USB device was no longer seen on the computer.

Mentioning this to John, VK2ASU, it turned out that he had exactly the same problem but he noticed that when he dropped the box it started working again - this suggested a bad solder joint.

There are some connections between the main board and the embedded TV stick and adding extra solder to the two points marked with red arrows has fixed mine.

Thanks to John VK2ASU for diagnosing this, I would have tossed it out except that I thought I'd used the nice box for something else.