First birthday

 

Today the blog is one year old - Happy Birthday, Radioworm !
During the last 12 months there were 50 postings made, the hit-counter shows 1759 pageviews and visitors came from Europe, Middle East, Asia and USA. "Circuits", 27th March, leads the popular posts table. This was a post that I was undecided about publishing at all !
In that time the frequency synthesiser has dominated my construction projects.
My activity 'on the air' on longwave has been the most newsworthy; country "firsts" were reported on January 8th, and an award received in recognition of my achievements, 6th February. My personal favourite post is that of the extreme loading coil, 19th February. Of all the pics of my longwave radio station which I sent a magazine columnist, I wish he hadn't chosen to publish the one of the coil.
On the 20th April I saw the volcano eruption in Iceland from space, thanks to the weather satellites.
In the next twelve months I plan to develop a family of synthesisers including basic models and more advanced variants, build a new antenna for longwave, complete the 700 watt transmitter amplifier for 144MHz, and make my first amateur radio contacts via the moon; all of which will be posted here if they come to fruition. So it seems I shall be in this corner of the workshop quite often !

DDS #2 on test

Today I continued with the development of the second prototype frequency synthesiser. I have added the facility of changing the tuning step size in real time.
It is shown being tested on the work bench alongside "MyDev2", ( PIC18F4550 microcontroller ), and "ICD2", ( debugger and programmer ).
The output voltage at 137.7KHz is a 1.32v peak to peak pure sine wave across 300 Ohm. There is no output low-pass filter and I think this is the reason the output level is about twice that of prototype #1, which incorporates such a filter, probably introducing significant residual capacitive reactance.

More "firsts" on longwave

Yesterday evening, Szigy, callsign YO2IS, in Timisoara, Romania, 710 kms away, and I had a contact on the 2190m longwave band, which we will claim as the first ever Romania - Poland contact on that band, thereby adding Romania to my two prior "firsts" with the Czech Republic and Belarus.
I copy part of Szigy's email which he sent to me soon after our meeting 'on the air', particularly because it emphasises how challenging amateur radio communication is on longwave; as I know only too well myself, even over distances of just a few hundred kilometres. Szigy wrote:

"Dear Steve pleased to run a fine QSO with you, the very first SP-YO on 2.2Km. Signal was nice but with a deep QSB on the midle of the QSO. At the beginning had some problem with a flashover in the teflon feedtrough my window, it take one hour to change the isolator.Will send you a direct QSL in the next days. Once more thanks for the new one ! Have fun on VLF it's always a big chalenge, gl."

One of the challenges is typically the use of short inefficient antennas, ( because of the nearly 2.2km wavelength ), causing high voltages of several KV to appear at various places in the antenna system. Unluckily for Szigy during our contact, he had to take time out to tackle a problem of insulator flashover !
Earlier this week, I cleared ice and snow from my antenna in order to make it useable once more; but even then I had a flashover problem which I was able to prevent happening again, and fortunately nothing went wrong at my end during the contact with Szigy.

Stop press: In the last few minutes I have achieved another "first", Estonia. Incredible conditions on longwave this weekend, and some stations active making the most of them. What a start to 2011 on 2190 !

Meteor scatter using the Quadrantids

The Quadrantids meteor shower, which appears to come from the direction of  the old star constellation of Quadrans Muralis near the Pole Star, has just intersected with the earth, as it does every year on the 4th January. I used the ionised trails produced as individual meteors burnt up in the earth's atmosphere to reflect my 50MHz radio transmissions to make contact with other radio amateurs in Denmark, Slovenia, England and the Netherlands by exchanging short, ( for obvious reasons ), text messages with them. The data transmission mode is called WSJT/JT6M, and I used the 500 watt amplifier featured on 25th January and 12th May 2010.
The screen shot shows one of Dick's, ( callsign G1CWP ), signals which I received during my contact with him in West Sussex, in the UK at a distance of 1451kms from me. The burst of signal has the characteristic profile of having been reflected by a meteor trail with its steeply rising leading edge as the trail quickly forms and peaks in intensity, followed by a more gradually falling trailing edge as the intensity subsides until the event is over.
I try to participate in all the major meteor showers during the course of a year; Quadrantids ( January), Lyrids ( April ), Perseids ( August ), Orionids ( October ), Leonids ( November ) and Geminids ( December ).