G3XBM webpages have moved

Today I switched my webspace from NTL to Google Sites. I've been having issues with FTP connection to the NTL webspace for weeks and the Virgin Media "help" has been anything but. I do so HATE having to press button 1 for this, 2 for that etc and in the end getting connected to someone who doesn't have a clue. No problem with the help centre being in India, but I would like to get help in the end. No joy.

So, I decided Google Sites would be a better bet. Google Sites is free, allows 100M of webspace and pages can be edited without HTML. There is also good feedback on site visit statistics using Google Analytics. The downside is the page formatting I can use is less complex, less fancy, but this is no big deal.

If you go to http://www.g3xbm.co.uk you will be directed to the right place.

In praise of the Asus EEE Netbook PC

For over a year I've used a little 7 inch screen Asus PC701 Netbook PC running the preloaded Linux operating system "as is" as my main PC. It has never crashed, always boots up in seconds, does 95% of what I ever need from a PC and is inexpensive. It went with me to New Zealand on holiday (allowing me to do a daily blog from hotel rooms and to video Skype our sons) and fits easily in the hand luggage. Today in the UK the version ships with 8GB of solid state memory (mine just has the 4GB) from around £151 brand new.

If you want simple, low cost and effective computing you'd be hard pressed to beat this little beauty. Of course there is now a lot of choice in netbooks with larger screens, XP etc, but for me the original Asus EEE is hard to fault.

SixBox 6m AM (improvements)

Been doing some more work on the SixBox AM transceiver and have come up with a simpler and better TX lineup. I abandoned the osc/multiplier in one stage and went instead for a 3rd overtone xtal followed by a modulated buffer and PA. The third overtone oscillator values shown ensure the crystal reliably oscillates on its 3rd overtone.

The little PA and buffer work well with just T37-6's as (untuned) chokes in the collectors of the buffer and PA followed by a low pass filter. This arrangement is very stable and simpler than before. Modulation is clean and deep. As it stands it produces 50mW of AM on 6m. A further single stage linear PA would take this to around 1W of AM, but I will leave this to others.

Lenticular (lee wave) clouds

The last few days I've been in the Yorkshire Dales area of the UK and was treated to a sight I'd not seen before - lenticular cloud formations over the tops of the higher hills in the Dales. These are sometimes called flying saucer clouds as this is just what they look like. These were all seen yesterday June 24th in the late morning. I only managed to photograph one (a poor example) as I was being driven and was unable to stop when the very best examples (really like flying saucers with nice sharp edges) were visible. A few hours later these had all disappeared. I expect these are quite common in areas like the Dales, but this was the first time I'd seen them.

For more information see http://en.wikipedia.org/wiki/Lee_waves

A very basic 4m AM transceiver

In the coming days I am planning to modify my SixBox 6m AM QRP breadboard to 4m so that I can have a first 4m QSO using my own callsign. As I don't have suitable crystals I was planning to use (very temporarily) a free running oscillator at half frequency, even though I might have to re-net to 35.13MHz (half 70.26MHz) quite often. Today, someone pointed out that the 14.060 crystals sold by GQRP club multiply x5 to 70.3MHz, which would easily pull down to 70.26MHz. Although a x5 multiplier won't be efficient, it is worth a go don't you think?

If things go to plan, I should have a very basic 30-50mW AM transceiver working on 4m by the weekend. It will be a rats nest on a piece of copper clad board, but it should allow me that first 4m QSO. Whether it gets put into a neat box remains to be seen.

[See later blog post on improvements to the TX lineup]

Cambridge Radio Club is 90

Today, the Cambridge and District Amateur Radio Club held a 90th birthday picnic at the village hall in Foxton, Cambridgeshire. The weather was good and there were plenty people there. The club put up antennas for HF plus 2m and 6m with the aid of the Cam Hams group recently back from Harris in the Hebrides. I managed to get along for a couple of hours in the morning and rejoined the club. It was nice to operate on 6m with a big station (QRO and a big, high yagi) for a change. The band was open to Europe and there were plenty of stations to work. In the afternoon, at home, I worked their special call GB0CAM on 2m FM. A nice friendly day.

The CDARC website is http://www.cdarc.org.uk/
Cam Hams website is http://www.camb-hams.com/

Transatlantic 6m summer super DX - what mode?

The usual assumption for the super-DX across the Atlantic from Europe to the Caribbean and S.America is multi-hop sporadic-E. Certainly the contact to K1TOL that I made a few years ago was by this mode.

But, with the recent questioning of the mode for the Europe to JA path on 6m in summertime, I am wondering if mesospheric cloud reflection is a possiblity for other extremely long paths too? YV and other places on the north of South America is some 8000kms away from here, yet people seem to work such distances every summer on 6m.

I'd welcome your comments and views.

QRP 6m multi-hop Es SSB QSO

Just switched on the FT817 at 0820z and worked EA8CQS (Canary Is) on 6m SSB with 5W to the vertical. DX was 3010kms. He was quite weak so surprised he got me so well.

Noctilucent cloud DX - microwave mega DX mode?

There was a MOST interesting note on the ARRL propagation report tonight:

"Noctilucent Clouds Return - As reported at spaceweather.com on June 1, the first noctilucent clouds (NLC) of the 2009 season were sighted over Russia on May 27. NLCs typically appear about 20 days prior to the summer solstice, increase quickly to a high summer level, and then disappear about 50 days after the summer solstice. These clouds are mostly a high latitude phenomenon, and are believed to be composed of ice crystals. VHF radars see very strong echoes from these clouds, and since they are at mesospheric heights (80 to 90 km), they are also known as polar mesosphere summer echoes (PMSE). These clouds are hypothesized by JE1BMJ and others to be responsible for 6m propagation across high latitudes (for example,
from the East Coast of North America to Japan) during the northern hemisphere summer. This mode of propagation has been dubbed Summer Solstice Short-path Propagation (SSSP). Check out page 34 of the February 2009 issue of WorldRadio Online (available free at
www.cq-amateur-radio.com/wr_back_issues.html) for a general discussion of PMSE and SSSP and for references in the technical literature. To reiterate, SSSP is still just a theory,
but the occurrences of QSOs appear to match the occurrence pattern of PMSE."

Now, there is also evidence (from radar returns) that microwave DX might be possible using the same noctilucent clouds, possibly allowing superb DX possibilities on 10GHz possibly even with low power.

This is a whole area of future ham research just waiting to be exploited. It may be one upside of global warming as these high altitude clouds are now more common than hitherto.

For more on these mesospheric clouds see http://www.chiandh.me.uk/p/Noctilucent_cloud#Results

The SixBox - A Simple 6m AM transceiver

NB There is an updated schematic uploaded June 28th 2009.

Well, I've completed a breadboarded version of the SixBox, an ultra-simple 6m QRP AM transceiver which I've had in my mind for some time. As it stands, without a linear, it produces around 50mW AM (200mW peak) from the 2N3904 series modulated PA. It is not in a box, just a rats nest on a piece of copper clad board, but it works. The receiver is a super-regen using MPF102s with an isolating RF amplifier loosely coupled to the super-regen detector. A varicap diode (to be added) is used to tune across the band. The TX consists of a 25MHz xtal, a x2 multiplier and PA both of which are series modulated. Ubiquitous 2N3904 transistors are used throughout apart from the super-regen stages.

Click on the schematic to see what it consists of. It would readily scale for 4m although the T37-6 toroids would be a bit marginal this high. I was surprised how well they worked at 50MHz.

I should be DELIGHTED if someone wanted to develop this circuit further and maybe produce a small PCB and case.

On reflection, I think the DSB version of this would be a better bet. Much of the TX line-up can be re-used for this but I would use a DC receiver. 200mW pep of DSB (equivalent to 100mW SSB) would be quite a useful power. My next project will be to complete the DSB version, either for 6m or 10m.