This antenna was one I bought in the early 90's for 11m use at a different QTH but took it down when I moved home. It has sat in the garden shed since then, slowly turning into a pile of aluminium oxide...
I dug it out from the shed and cleaned it up then tested it on an MFJ Analyser. It was perfect for its design frequency at 27.5Mhz but I wanted to bring it up by a whole Mhz to centre at 28.5Mhz.. as it was designed to be a throw together antenna there was no adjustment that would bring it that far up in frequency. I ended up taking a hacksaw to the top section and removing 5cm bits until it came to where I wanted it. In all I took 20cm from the top section.
I then had to make some new radials for it as the old ones were damaged beyond repair. I measured 3 radials from aluminium which came from my damaged 6m beam. They clamped in as direct replacements for the originals.
I fitted it on the pole where my vhf and uhf beams were mounted with an air wound RF choke to stop any rf coming down the coax outer. The base of the antenna is around 11m above ground with the tip another 7m higher.
Close up of the 'Ugly Balun' Choke