Showing posts with label construction. Show all posts
Showing posts with label construction. Show all posts

Sunday, 31 July 2011

Voltage Probe Antenna - Part 2

This weekend saw a family visit (wife, grown-up children, and in-laws) trekking across the Pennines to the Sunderland Air Show, and a Jolly Good Day Out was had by all.
As with the Windermere Air Show we attended a couple of years ago, the only flying Avro Vulcan XH558 once again stole the show.  What a stunning aircraft, and what an impressive noise!

A fly-past with the bomb bay open

Today, in between watching the Hungarian Grand Prix and listening to the Second Test against India at Trent Bridge, I managed to get the prototype Voltage Probe Antenna completed and fired up for a quick test.

It certainly works, and in the brief period of time I had to test it before I packed up for the weekend, I had received amateur signals at good strength on all bands from 160m to 15m ,with the exception of 60m.

First VPA lash-up
I also had broadcast signals on Long Wave and Medium Wave at decent strength.  Next week I hope to carry out a more extensive evaluation, and naturally I will probably report back here.

This first version doesn't have the required circuitry to be powered from the output coax cable, this will follow in due course, no doubt.

Sunday, 24 July 2011

A new project - the Voltage Probe Antenna

About this time last year I paid a visit to an old radio amateur friend whilst away on holiday, and he was enthusing at the time about a little "Active Aerial" he had built very quickly more or less from parts in his junk box.   This little aerial was about the size of a beer mat and was suspended from a piece of shelving, and was connected to his FT-817.   All kinds of stuff was being received, most impressive.

This was to a design by PA0RDT.

Moving forward to more recent times, in fact last weekend, I noticed from EMail traffic that our local radio club, the Eden Valley Radio Society were possibly embarking on another club project, and an "Active Aerial" was one of the contenders.   Ron, G4GXO (proprietor of Cumbria Designs) had come up with a circuit in part inspired by the PA0RDT design and it was mooted that this might be the basis of such a project.

Naturally my previous experience caused my ears to prick up, and after some correspondence with Ron I now have a new project - to build this little circuit and evaluate it.

In terms of complexity it is completely different from the "Eden9" project, in that an experienced constructor should be able to build it more or less as a "weekend project".   Looking at the modest parts requirement I realised that had all that was needed available and resolved to give it a go this weekend.

However, as is the way of the world, outside influences intervened, a major influence being the unexpectedly fine weather we were blessed with - cloudless blue skies and pleasant temperatures, so in the end I only got chance to get this project started, hopefully to be completed next weekend..

The aerial including the amplifier is all contained on the single piece of PCB - the photo below shows the project getting under way before I tidied the garden shed up to placate my XYL who insists on doing "things horticultural which I don't understand" in it whilst I am not around!