"Portable" in the back garden

I never got my act together for the 4m Trophy contest and I haven't got an antenna at home.  So ....... time to erect a temporary antenna.

This is the G0KSC 6m/4m 4+4 element design carefully modelled and tweaked to work with 9.5mm tube elements rather than the original 12.5mm elements.  Seen here on a 20 foot scaffold pole surrounded by houses and trees.  GB3ANG was audible throughout the weekend.

The contest started with a band with Sporadic-E into eastern Europe.  In the first hour 8 QSOs were made into HA, OK, S5 and 9A.  Tropo conditions were average and certainly favoured those in the North.  Forty one contacts were made in the first 4 hours and then the antenna was removed to make way for the BBQ !!

VHFNFD - WOW !!

To celebtrate the RSGB Centenary the Weather and Radio Gods got together to produce a spectacular VHFNFD.  Clear blue skies and the best conditions I've heard on 70cms for many a year.  I provided the 432MHz station for the Pembrokeshire Contest Group in IO71OP.  Again this was a single operator experience involving all setup, operating and tear down.  The two new HA8ET preamps worked flawlessly and, given the strengths of some of the DX, definitely improved the performance of the system.

Conditions were excellent into SW France and Spain throughout the event and into PA/ON/DL/OZ/LA during the Saturday evening.  In all 199 QSOs were made into 54 squares with an average distance of 501kms.  The best contact was into JO62 at 1207kms and there were 31 contacts >900kms.

It could have been much better but interference from the 144MHz station lost the majority of the first four hours of the event.  Then to cap it all, I got 200 yards out of the field and suffered a front tyre blow out.  Where is the jack - that would be under all the kit you have just packed into the Land Rover!

Homebrew PCB - do theory and practise agree?

Two years ago I was arm twisted to provide the 432MHz ststion on VHFNFD for the new Pembrokeshire Contest Group. I could write a book on the trials and tribulations of resurrecting a system that hadn't been powered up for probably ten years plus. One challenge was to turn it into a twin system transmitting into two antenna arrays. This required an unequal power split as the two PAs needed different power levels. After some frantic last mninute experimentation, a coupled line power splitter was made by hacksawing some copper board to make the two lines and supergluing them to an earth plane - it worked remarkably well. The split was about -11dB. The design was created using the coupled lines model in QUCS. Roll the clock on two years - can we do better in terms of a power splitter?  A lower split of around -8dB would be nice, but would that be physically possible with very closely spaced lines? The design was done in QUCS, implemented in DesignSpark and then the board produced using my homebrew UV exposure unit. The design called for lines 12.5 thousands of an inch apart.

 

The interesting part was just how long it took to etch the narrow gap between the lines.  I normally reckon about 90 seconds to etch a board.  It took a further eight minutes to etch that fine gap.  Looks good but does it work?

The impedances look good on the network analyser but sadly the coupling is about -11.5dB.  I nor actually believe that coupled lines reach a limit at around this degree of coupling.

I will try the old hacksaw produced version and this rather better looking version on the VHFNFD site to compare performance.  But an interesting exercise to use two software packages and the home PCB facility to produce a nice looking product.