Sunday, 31 August 2014

New Anglian transverter PCBs

First sight of the new PCBs for the next batch of 144 and 70MHz transverters!
Beautifully made boards with gold flashing rather than tinned.
Now to order even more parts to populate them..........
Pictures later.
Sam

Saturday, 30 August 2014

Return from EME2014

It has taken me several days to recover from the trip to EME 2014 in Brittany. Not because of the travel but because of illness. Somewhere I managed to ingest some shellfish. I never knowingly ate any, but...... It has taken until today to get my appetite back!

Illness aside, it was a good Conference, with lots of interesting information gained, enthusiasm for EME renewed and, more importantly, lots of old friendships renewed and new ones made.

Pleumeur Bodou is an interesting place. As well as being a world famous satellite site, where the first successful transAtlantic transmission was made from Andover Maine to Europe (when Goonhilly mixed up left and hand and right hand circular polarisation) in July 1962 on Telstar, it is on the Rose Granite Coast with lots of spectacular great granite boulders all along the coast.

I worked their 5.7GHz amateur band EME station, TM8PB, back in 2012, using my 2.3m EME dish, so was pleased to personally see the station at the other end of my contact.

In the photo you can also see a long 2m EME yagi bolted to the side of the dish!


In all there were 110 registered attendees plus a number of partners, making a total in excess of 150. The Pleumeur Bodou radio club hosted the event with the organisation being made by F2CT and his XYL together with a number of other French radio amateurs. They did a great job ( except for the weather!). 
It rained on and off for the two days of the Conference, with a long enough break to take the group photos. These will appear elsewhere in due course. I wasn't able to take any group photos this year.

An enjoyable few days. My thanks to the organisers for a job well done. Maybe a few points off for the caterers................!

The next International EME event is scheduled for Venice in 2016.

Sam







Friday, 22 August 2014

116MHz frequency locking

At last I got round to connecting my ZLPLL 116MHz source to the Anglian 144MHz transverter.
I am pleased to report it works really well. I could detect no difference in the quality of received signals supporting the observed good phase noise 'measured' on the spectrum analyser.

I was initially a bit concerned at the high level of the source harmonic output. However, when connected to the Anglian it injection locks the internal 116MHz crystal oscillator, leading to a really clean injection signal. 

Monitoring the 144MHz output, with the input 28MHz drive signal supplied by my R&S SMG low noise signal generator, the output spectrum was just as clean as with the internal ( unlocked) oscillator.

Driving the ZLPLL with a clean 10MHz GPS locked reference signal from the SMG, the Anglian signal sounded excellent. I am really pleased with these results, which I will be reporting in my talk at the EME Conference in three day's time!

The ZLPLL as used to provide the locked 116MHz LO for the Anglian.

Google ZLPLL for details of the source. Note that Wayne can no longer supply the OCXO version of the Source, although TCXO and external-only versions are available and OCXOs may be back in due course.

Sam


Thursday, 21 August 2014

EME 2014

Early Sunday morning Dave, G4HUP, and I will be off to France via Weymouth and St Malo 
for the EME2014 conference, being held in Pleumeur Bodou, Brittany, on Monday and Tuesday next week.
Pleumeur Bodou is the site of the former French TransAtlantic satellite station and is credited with making the first successful TransAtlantic TV transmission with the USA. Goonhilly had previously failed due to a misunderstanding as to what defined the sense of circular polarisation to be used! I well remember Richard Dimbleby, on the BBC, sat waiting for the first pictures from the USA and seeing a terribly noisy picture, that was decidedly unusable. FranceTelecom got it right the following day. They weren't first, but were first with a good picture.........there, that will get me into trouble with our French hosts!

I am very much looking forward to the Conference. This will be my fifth EME Conference, the first being in Wurzburg, Germany, followed by Florence, Dallas and then Cambridge. It will be interesting to see where the next one will be. We will be voting for the next venue at Pleumeur Bodou. Venice is one of the known proposals for 2016

My presentation slides are now finished (apart from the usual final polishing that always takes place....) and they now contain new data on the performance of the Anglian 144MHz transverter. It has been interesting preparing the talk for a generally technically well-versed audience from across the globe.
I hope to use the same slides in my talk on the Anglian at the RSGB Convention in October.

Unfortunately, I have been inactive on EME for more than two years. I am currently looking at a smaller dish for use at 10GHz. It should be easier to steer onto the moon and will give me an opportunity to develop my 10GHz capability. Much of the 10Ghz gear is ready to go, but I have only just found a source of suitable dishes.

I hope to have more to say about 10GHz EME in due course.

Sam






Tuesday, 12 August 2014

Filters for beacons

Today I built two 432MHz beacon low pass filters. One is destined for GB3UHF in Kent and the other for GB3NGI in Northern Ireland.
The filters were designed using ELSIE and the implementation is silver plated wire coils and paralleled ATC fixed capacitors and 6pF Voltronics ( I think) ceramic trimmer capacitors. The filters are assembled in small Eddystone diecast boxes with 17mm flange N female connectors as shown.

The measured performance of the filters matches the ELSIE predictions quite well. Insertion loss is below 0.2dB with a return loss of well over 20dB ( depending slightly on tuning for minimum insertion loss).

Sunday, 10 August 2014

Frequency locking 116MHz

I spent part of the day playing with frequency locking my Anglian 144MHz transverter.
The transverter has facilities to either inject or extract a 116MHz LO signal.
Although I had conducted this test previously on my DDK2001 source board, I still needed to check that it also worked with the Anglian LO.
I was pleasantly surprised to see just how far off frequency the on-board 116MHz could be and still lock, with extremely clean output.
Not only that but the level of external 116MHz required to achieve lock proved to be extremely small, easing the requirements on the external source.
This has raised the possibilities of sub harmonic locking! I will be exploring this over the next few days.
All this is being done as content for my EME 2014 Conference presentation.
Sam

Monday, 4 August 2014

My grandfather in WW1

I am posting this as a tribute to my paternal grandfather, Edward Jewell.
'Ted' joined up to the Royal Sussex Regiment on the 19th February 1915 at the age of 18.
He was sent to France on 10th December 1915

On the 14 February 1916 (St Valentines day) he was wounded by shell fire and evacuated to Boulogne and thence returned to to England on the St David hospital ship.

After several months in the Norfolk Hunstanton VAD hospital he was turned to France on 29th September 1916. To the Somme, again!

He still had shrapnel in his upper body. It could not be removed without further damage.

On November 28 1916 he was digging a trench in the Somme when it caved in on him. He and others were buried or trapped.

My grandfather was buried up to his waist in mud and water for three days. When found and dug out he was evacuated  to an unidentified field hospital in France. There he was diagnosed as having trench foot and subsequently had both feet amputated on the 12th December.

He was returned to England and then had a double Syme's amputation of his lower legs. Separate to the removal of his feet.

He spent months at Roehampton hospital recuperating and for the fitting of artificial limbs.

He married Grace in November 1920. My father was born in 1921.

Ted lived until he was 72 when he died of a massive heart attack at the Royal Berkshire hospital in Reading. 

He suffered deteriorating health from the time of his amputation, but managed to live a full life.
I am very proud of my grandfather.

Sam