NSW Home brew meeting at dural

We gathered at the WIA Dural site today for a show and tell and a talk on recovering components from PCBs.

The construction of the new shed is progressing well.



Contrary to my first guess, that isn't the roof on top of the slab, it's the walls.

There was the usual bits and pieces of interesting junk to pick through.



John has built a brilliant 3 transistor high gain audio amplifier that can drive headphones from small signals such as those from a direct conversion mixer.



Kevin showed a helical antenna he built for a Telstra wireless broadband setup on the edge of coverage.



John also showed a loop antenna for 40 and 80m built in a hula hoop.



The main presentation by Mark went through all the normally expensive or hard to obtain components that can be found for free in discarded circuit boards.



Mark had lots of practical tips of getting components off boards with plumbers soldering irons, gas jets, and heat guns. It's not a subtle art.

Update

Alan, VK2ZAY has a nice writeup too.

8 Pole IF from VK3EPW

I've been publishing design and construction notes from Peter, VK3EPW and he's sent more information on his 8MHz IF. Rather than creating a separate post it's been integrated into the original article here.

Check it out! Peter's construction and dedication to shielding is something to behold.

Thanks for sharing Peter.

Home brew 80m DSB first contact

I finally debugged my rebuilt 80m DSB transmitter based on the design in Drew Diamond's first radio projects book.

The first version suffered from RF instability due to my poor wiring.

I've probably gone a bit overboard with nice metal boxes for the three parts: exciter, power amplifier, and 4Mhz low pass filter stages but it's paid off.



Very kindly Sam VK2BVS came on to the frequency and we had a good chat. At first he reported that I was distorted but in the end came to the conclusion that it was just that I'm about 50Hz lower than the 3670 crystal is labelled.

Later he said the audio was fine and the carrier very low (we've very close).

Anyhow, for me, this is a great achievement. I guess the next logical step is to build a receiver for the same frequency and a better arrangement for switching between transmit and receive - it currently involves plugging and switching.

Broke his neck erecting aerial

No, not me thank goodness. I enjoy looking at the 100 year old photo archive and today searched for "ham radio" and stumbled upon this excellent photo and thread of info.



It seems that poor Lester Picker fell 55 feet while erecting an aerial for the radio shown at his bedside. Poor chap.

Motels with "free wireless broadband"?

Sounded too good to be true, and yes it was. We stayed at the Sandcastles apartments at Coffs Harbour which advertised "free wireless broadband".



As we checked in I noted two WRT-54g routers on the reception desk. It turned out that the "freeness" only amounted to half an hour of use, after that you had to buy tokens in inconvenient combinations of hours and expiry times.

They are running Chillispot and I certainly experienced some outages where I couldn't get an IP address from the DHCP server. I rang reception and she had just one possible action which was to restart the router. That didn't help. I wasn't too fussed and after a few hours it started working again.

I really wish I could tether my iPhone and just use that for internet while on the road.

The other amusing thing about Sandcastles was these amazing deck chairs that rather reminded me of the furniture at the milk bar in a Clockwork Orange.

The Mid North Coast Radio Expo 2009

Just attended the Mid North Coast Radio Expo and had a fine time.



Chatted to lots of people, had a good look at the exhibits, bought a few bits and pieces. Here's a photo tour for those that couldn't make it to Coffs Harbour this year.

Here's the nice lady who takes your $5.



Lots of displays around the walls and down the centre of the hall.



Lee Andrews had an excellent range available. I bought a co-ax switch.



Bushcom had HF whips on display.



A great display of home brew equipment.





Not sure who was on this desk.





Valves for sale.



VK4ICE imports some nice portable whips, I bought a pluggable 80m-6m whip for $119.



Very nice chaps.



The SES folks were very friendly and showed me the HF AM radios that are still in use by some.



Some tempting second hand gear at good prices.



A terrific display of Elecraft gear.



Including the tempting KX1.



VK2TOM had some rubidium frequency standards for sale.





The WIA was there, but the only book on display was the 2009 Callbook, so I bought one of those.



An extensive display of vintage radios.



The pedal from a pedal powered radio.



Just to show my wife, there really are other people with call signs embroidered into hats.



Foxhunt gear.



This sniffer from VK3YNG looks very nice.





Outside a very solid portable tower was on display.



I met and had a great chat with George VK4FGHT.



All up, a wonderful day.

Thanks to everyone who organised this and put in so much effort to make it all happen on the day.

The weather was great despite being too hot and then too wet in the days leading up to the big event.

Ham radio is a wonderful hobby and I enjoy meeting other enthusiasts very much.

Finally here's me in my new hat that has the family most amused.

See you next year.

Visiting Coffs Harbour for the Mid North Coast Radio Expo

It is once again my great pleasure to combine a family get-together with the annual Mid North Coast Radio Expo. Today we drove seven hours from Sydney to get to Coffs Harbour.



Accommodation is pretty basic.



Just kidding, we're a couple of doors up the road.

Walking on the beach today was humid but very nice.



Yeah yeah, the iPhone camera isn't too good but at least I have it with me at all times.

We'll have a look around on Saturday, catch up with friends and family, and prepare for Sunday's entertainment.

What's new in iWork 09

At first glance the new iWork for 2009 looks very similar to the past version, but there are a few features and some polish that makes it a worthwhile update.

My favourite is the full screen view. Command-Option-U and the whole distracting desktop goes black and all you see is your document, along with the word count and page number. It's a great way to really focus on the task at hand.

When you move the mouse to the top of the screen the menu bar appears.

As a long time fan of outliners as a way to structure a document, and re-organise, it's great to see a superb implementation in Pages.

I'm not a big Keynote user, but there's no doubt it's the best presentation software by a long stretch. The iPhone remote control is genius. I notice that one of the fancy new transitions is not available on my Intel Mac Mini.

Numbers has much more functionality than I've ever used so for me it looks the same.

Overall the programs seem a little snappier and certainly the use of animation transitions is done well without becoming gimmicky.

Apple doesn't harp much on what's new in iWork so I guess there's still a lot of people coming to this suite for the first time.

Export seems to have moved from the File menu to the Share menu. There seems to be a bit of overlap between these two menus, I would have thought that Share might be a part of File.

One slight wrinkle in the purchase process, I downloaded the trial and used it a bit before ordering via the online store. When the box arrived I looked for the serial number that the trial said I'd find in the install book.

It turns out that you just install from the disk that comes in the box, there's no serial number so the story's a little confusing there.

Anyhow, I'm over Microsoft Office. It was virtually mandatory for so many years. iWork opens Office documents without issue and these days I tend to distribute my writing as PDFs so all bases are covered.

Built an 80m DSB transmitter - VK3XU's "simplex sidebander"

Spurred on by the success and what I've learned from my battle with the Bitx20 I sat down and constructed a transmitter from scratch.



It's the "simplex sidebander" from Drew Diamond's "Radio projects for the amateur" first book. Dave, VK3ASE kindly gave me a couple of crystals for 3.670MHz when I visited recently. As you can guess I skipped the crystal filter and made it a double sideband exciter.



The circuit has a 741 Op amp as a mic pre-amp, an NE612 as both the oscillator and mixer, followed by a 2N2222 buffer. That big three terminal thing is a vastly overrated 7806 voltage regulator.

Two more RF stages, comprising a 2N3053 and an IRF510 are on the second board. Finally there's the output low pass filter. I'm waiting for some more Amidon T50-2s to arrive so I can add the other filter stages.

It looks ok on the CRO (me saying "haaalow") and sounds reasonable on the local radio.



When there's no audio, carrier is well supressed. When speaking, I get a nice 6W out by the looks.



My construction is pretty sloppy, leads too long etc, but hey - it's 80m so pretty forgiving thankfully.

I've learned an important lesson: when a toroid is required don't just grab a random loop from the junk box, try to get something of the same material! The Amidon toroid numbers, such as FT50-2, mean FT = Ferrite, 50 is the size, 2 is the material. So, substituting an FT43-2 worked fine.

Toroids.info is a good place for specifications and winding calculators.

Update

With the help of Mike, VK2MJW, I've determined that my on-air audio is very distorted. I put this down to the RF power stages being unstable.

Interestingly the transmitter behaves quite well on a dummy load, but when connected to a real antenna tends to go into oscillation.

On it's own the exciter board sounds good. I've mounted the exciter in a nice shielded box and am currently re-building the driver and PA stages with more compact construction.

Ham radio on Mac with Parallels

While there is some excellent ham radio software for the Mac such as CocoaModem, Aether, EchoMac, and DSP Radio, there's a lot of good programs which are unfortunately only available for Windows. One of my favourites is CwGet which seems to be the best Morse decoder around.



In the past I have tried Parallels but have always had problems getting sound in and out of the Windows virtual machine.

I've just upgraded to Parallels 4 and, apart from being generally smoother, simpler and faster; connecting a USB device such as the SignaLink USB I use for radio interface seems to work really well. Here's the preferences I use:



It's no surprise that the two operating systems compete for the USB audio device. I had CocoaModem running and then started XP under Parallels and CocoaModem's waterfall froze. The program was able to quit cleanly.

Anyhow, this is all much more convenient than a separate machine just to run Windows ham radio software.

Parallels 4: recommended.

Update - transmit audio trouble?

Haven't quite diagnosed this yet but I ran WSPR under Parallels and while I could spot other stations, no one spotted me. I listened to the off air audio and it didn't sound as pure as normal.

I take that back, it turned out that a station that should have received me had a problem. The run over night shows that wspr runs fine under parallels.



But the best news was that I spotted old friend Ross, T61AA, in Afghanistan multiple times over night. (He's the person that got me started with WSPR).

Bad taste banner ads - lose weight with Jobs?

Was up early tracking the MacWorld keynote and noticed that the Sydney Morning Herald had a story about Steve Jobs mystery loss of weight that has led to him not presenting this year. Note the tasteful banner ad at the top:



As for the MacWorld announcements, a little disappointment. We were all dreaming of a tablet, iPhone nano, iPhone maxi, new Mac Mini.. I am pleased that DRM is dying in the iTunes store - that whole thing was a bad dream.

I'll be chatting about all this on ABC Radio National after eight AM this morning.

Completed Bitx20 finally

I've been working on a bitx20 for too many months and have had a bit of a frustrating time getting it going. At last it's in use.



As you can see, I built the excellent Hendricks QRP Kit.

All of the problems along the way are my own fault, and everything is clear in retrospect.

It got a lot of help from the following places:

• The Yahoo group


• The official assembly manual


• Great videos from kc0wox

The main problem I had was that one of the wires from trifilar torriod T6, the balanced mixer wasn't connected. I couldn't null out the BFO and I didn't really know what to expect there. With the help of the Yahoo group I checked and re-checked T6 until it started acting correctly.

The second problem I had was that somewhere along the line, misusing a GDO I took turns off L4 and L6 such that they were way off resonance, this made the receiver work but was very deaf. In the end I visited the very kind VK2ZAY who quickly identified the problem using "math" (as he puts it).

The only remaining issue is that I have a couple of birdies in the tuning range, not quite sure why.

The receiver is sensitive enough to hear band noise, so that's enough. Switching back and forth between the bitx20 and a modern commercial rig the only real difference is the lack of ACG, all the same stations are audible.

I get about 10W out at peak and it sounds reasonable.

The Hendricks kit is excellent and certainly lots of people have built it without issue. The only comments I'd make are that it's pretty dense and if you are having trouble, like me, it's heavy going to trace. The wire supplied for the torroids has the kind of insulation that doesn't come off with heat and I did find it hard to scrape off without nicking the wire.

First contact!

I called in, inappropriately, on a very active DX net on 14.183Mhz today and John VK7XX graciously took my call and gave me a 5 and S7 report.



After earlier failing to be heard by VK3EPW I hooked up the cro and a dummy load and saw that with the headset mic plugged in I was prone to RF oscillation. A bit of ferrite around the place has reduced it.

John says my audio is a bit distorted and there's some crackling so I have a bit of work but that's a great result.

Just had a contact with Laurie, VK3AW (in Melbourne) and he also commented on the audio but was able to copy me well and said the signal was very strong.