This article continues on from Workup of G5RV inverted V using high strength aluminium MIG wire and describes the implementation.
Above is a view of the steel mast with the Inverted V G5RV rigged from the top of the 11m mast using a halyard though a purchase on a small gibbet to offset the antenna and feed line from the mast. There are lateral guys at 7m height, and the left hand one is non-conductive synthetic fibre rope. Atop the mast is a 2m/70cm vertical.
Above is close up view of the dipole feed point.
The open wire feed attaches to the dipole legs using stainless steel clamps shown above in mockup. the actual construction was liberally coated with marine grease to exclude oxygen and water from the electrical contact.
Above is a view from one support post to the feed point. A winch type agricultural fence strainer is used to adjust wire tension for the desired sag / tension (4.4N) to withstand 144km/h windspeed with safety factor 3.5.
The feedline option used was the Sotabeams 110mm ABS/PC spacers.
Above is the Sotabeams 110mm spacer threaded with the 1.6mm aluminium wire.
Above is a view looking up the feed line which is twisted and supported away from conductors (the lateral guy to the right is non-conductive).
Above is a view of the feed line approach to the cable entry panel. Again, liberal use of marine grease to exclude oxygen and water from the balun terminals.
Above is the balun and cable entry panel. The balun is described in a series of articles starting at Design / build project: Guanella 1:1 ‘tuner balun’ for HF – #1.
Above is detail of the insulator termination.
The technique for the right hand connection is shown in a video. The tail is 7×19 galvanised FSWR swaged at the insulator, but almost anything could be used.
On the inside of the feed entrance panel is a 300mm RG-400 jumper to an ATR-30 ATU. This is the so-called tuned feeder implementation described by Varney in his papers detailing the G5RV.
This antenna system is as described by (Varney 1958), the famous G5RV. Above is Fig 2 from (Varney 1958) where he details the purely open wire feed (or “tuned feeders”) configuration. (The scan is poor, the right hand side of L2 connects to the right hand side of the variable capacitor at the bottom of the schematic.) The ATU used though is a T match with an effective 1:1 current balun and 50Ω coax to the transceiver
On test, it works just fine… but the true test is its survival and performance over time.
References / Links
- Varney, Louis. July 1958. An effective multi-band aerial of simple construction In RSGB Bulletin July 1958.