Improved quarter wave line connections

On my 2m EME array the dipoles on the DG7YBN design GTV 2-12n XPOL Yagis are fed via quarter wave balancing lines made up from Andrew Heliax LDF4-50A. These lines are constructed using similar methods described on the DG7YBN web site - A serious QRO Quarterwave Line and have been in use since July 2020.

Over the last 3 years I’ve had a couple of instances where pigtails soldered to the coax cores have worked loose, probably due to mechnical vibrations, resulting in an intermittent connection for one Yagi.

Original method using 2.5mm o/d copper wrapped and soldered around coax core.

New method using a 10mm length of 5mm i/d copper tube with a 2.5mm hole for the pigtail. The tube slides over the solid core of the LDF4-50A.

Copper tube and pigtail soldered to core of LDF4-50A. Pigtail attached to dipole via standoff.

The dipoles only needed a small adjustment to get a return loss better than -40dB.