Sunday, 27 January 2013

New 144MHz antenna

Last summer I erected a YU7EF dual band 4/6m five element yagi on my mast. A few month's ago I asked Colin, G4ERO, if he would also make me a 5m boom 144MHz YU7EF yagi.

Yesterday I took delivery of the new yagi at the monthly Codger's breakfast meeting, courtesy of G4BAO and his delivery system!

Taking advantage of the mild weather today, I assembled the yagi and put it on my mast, ready for testing.

After normalising the cable I was able to check the match direct at the yagi feedpoint, using my HP 8753C network analyser.

This showed the best match to be slightly low in frequency at 142.8MHz at 25dB, rising to 16dB ( about 1.3dB VSWR) at 144.3MHz.
I didn't have time today to play with the match, but suspect that the coax balun is slightly too long.

Next time I have the mast down I will shorten the balun by a few mm and check the match.

Listening around on 2n there wasn't much activity today, but the usual beacons were all there and about their normal strength, although a longer period of listening is required to see if their level is better or not. My 'old' Cushcraft 145B2 ten element was quite good, but it is not an optimised design, so I would expect marginally better performance on terrestrial and a fighting chance at single yagi 144MHz EME.

73 de Sam

Posted using BlogPress from my iPad

Wednesday, 23 January 2013

Dubus Technik 12

Received my copy of DUBUS Technik 12 today.
Full of really good stuff including a reprint of my PGA Amp.
These were also on sale at Heelweg last Saturday.

Copies should be available from the UK DUBUS representative, GM4PMK.
Google on Roger's callsign for details.

I guess they will also be available elsewhere from the numerous DUBUS country representatives.

Speaking of the PGA Amp, I now have a small number of low loss Arlon PCB versions of the PGA Amp kit. See my web page.
This will be updated in a day or so to reflect the availability of this 'other' PCB.

- Posted using BlogPress from my iPad

Monday, 21 January 2013

Heelweg and Dwingeloo

Safely back from The Netherlands.
We ( G4BAO, G4HUP and myself) had been concerned that the dreadful snowy weather at the weekend might have meant calling off our annual visit to the Heelweg Microwave meeting ( held in Westendorp!) on the 19th January this year

As it happened it was probably a wise move to drive rather than taking a plane as in previous years. The delays experienced on some airlines just did not occur on the Stena ferry Line Harwich to Hook of Holland route and although progress was slow across The Netherlands road network on Sunday ( I was interested to see that the Dutch are no better prepared for snow than here in the UK), at least everything kept moving.

This is the first time we have taken the car, and it may not be the last. It allowed us more freedom in our schedule and the opportunity to visit the Dwingeloo dish in JO32. As this is a long way from our usual host's QTH, there has not been enough time to visit previously.

Jan, PA3FXB, had invited us to visit many times over the last few years. At last, and just after the dish was place back on the rotating plinth following refurbishment, we were able to look over the site and admire the handiwork of the original builders back in 1954/1956

This dish was used by Jan Oort of 'cloud' fame to map the galaxy HI line for the first time and is one of the sites at which the ashes of famous radio astronomer and radio amateur, Grote Reber, are intered.

The site is now well known as the location of the PI9CAM EME operation on 2m and 23,13 and 9cm

EME operation will not resume until later this year, and when it does I would like to go back again.

Next to the dish, on the Astron test range, we saw one ( or more) of the low frequency LOFER array antennas. It is shown right in the very middle of the photo and appears as a small black disc on the top of that short pole.

The Heelweg meeting was its usual excellent self with over 150 attendees, lots of test gear in use and a small number of traders doing a good trade in specialist parts for microwavers.

I would like to thank Jan, PA3FXB, for taking time to show us round the Dwingeloo dish, and to the many organisers ( too many to mention) who organise and run the Heelweg meeting.


- Posted using BlogPress from my iPad

Thursday, 17 January 2013

Heelweg plans

Still packing stuff to take to the Dutch Heelweg Microwave meeting on Saturday. However, the weather looks like it means to try and intervene. Snow expected in East Anglia from lunchtime tomorrow. The forecasts are for low amounts in this area so driving across to Harwich may not be too big a problem. We'll see!
What awaits us on the otherside of the North Sea is possibly a bigger concern.
I am looking forward to seeing the refurbished Dwingeloo dish on Sunday. I hope we can make it.
More anon!

On another matter, I have been asked to produce the March Radcom VHF/UHF column prior to the new, permanent, columnist taking over from the April issue. I'm busy soliciting reports for the end of January deadline.
In particular I am interested in any reports, for any of the VHF bands, from the Quantrids meteor shower. If you have a report you would like to submit, preferably with a picture of your antenna system, I would be pleased to receive it.

- Posted using BlogPress from my iPad

Tuesday, 15 January 2013

PGA Amp updated documentation

I have updated the PGA Amp VHF preamplifier documentation on my web page,
In the PDF several minor schematic errors have been corrected and the type of housing has been changed to show the preamp mounted into a smaller and easier to work with tin plate box.
The documentation also now gives details of G4SWX's 130MHz HPF used, when required, with the PGA Amp to give added protection against strong Band 2 FM transmissions.
- Posted using BlogPress from my iPad

Tuesday, 1 January 2013

A happy new year?

Once again circumstances intervened. My good intentions to get on the new 472kHz band on 1st January were thwarted by a bereavment in the family on New Year's Eve. The next week or so will be taken up by funeral arrangements and further trips to GI.

On a more positive note, the hotel has been reserved near Heelweg, the ferry has been booked and we are now all set for the Heelweg Microwave meeting on the 19th January, followed by a trip to see the restored Dwingaloo dish (PI9CAM) antenna on the 20th January.

John, Dave and I are looking forward to seeing our ( mainly) Dutch, Belgian and German amateur friends once again. Expect to see a full report on the Heelweg and Dwingaloo visits in Scatterpoint and, perhaps, Radcom.

Happy New Year

- Posted using BlogPress from my iPad