There are many posts and ideas on the internet on how to construct a dipole for HF use on the amateur bands.
My original plan was to make a half wave 40m dipole, 10m each leg supplied from 300 ohm ladder line.
But I came across the design for the G5RV which every one seems to rave about.
So I ended up converting my 15m long wire to the dimensions of a half wave G5RV for 40m. The results are very disappointing.
It works better with one half of the dipole disconnected from the balun, and I am a little mystified as to why. My long wire antenna worked better as an all round antenna, tuning up on nearly all bands except for 160m band.
The layout is similar to that seen in my original drawing below, except the dimensions of the half wave dipole are cut to those given for the G5RV 40m dipole, which is 15.55m. The 300 ohm feed line goes direct into the balun in my MFJ 949E ATU.
The antenna does just about tune up on 40m but is hopeless on any other band.
I have been wondering if the balun fitted to the MFJ atu is suitable both in size and the way it is connected in to the circuit.
The balun is barely 1 inch diameter. There is a wire connecting from the upper binding post (just visible in the upper left corner of photo) to the centre binding post (black wire), to connect the "wire antenna" to the balun black wire.
The 300 ohm balanced feeder connects to the binding posts with the black and white wires. Please see diagrams below.
I have no idea how the dimensions of the G5RV have been arrived at, as it does not correspond to anywhere near a half wave of 40m, I am surprised it works on 40m at all.
I am wondering if it would be better to revert to my original plan of making each half of the dipole 10m long with a slight overlap at the far end.
Advice and comments would be very welcome. I have also posted this on Golborne.
Thanks
Mike
My original plan was to make a half wave 40m dipole, 10m each leg supplied from 300 ohm ladder line.
But I came across the design for the G5RV which every one seems to rave about.
So I ended up converting my 15m long wire to the dimensions of a half wave G5RV for 40m. The results are very disappointing.
It works better with one half of the dipole disconnected from the balun, and I am a little mystified as to why. My long wire antenna worked better as an all round antenna, tuning up on nearly all bands except for 160m band.
The layout is similar to that seen in my original drawing below, except the dimensions of the half wave dipole are cut to those given for the G5RV 40m dipole, which is 15.55m. The 300 ohm feed line goes direct into the balun in my MFJ 949E ATU.
The antenna does just about tune up on 40m but is hopeless on any other band.
I have been wondering if the balun fitted to the MFJ atu is suitable both in size and the way it is connected in to the circuit.
The balun is barely 1 inch diameter. There is a wire connecting from the upper binding post (just visible in the upper left corner of photo) to the centre binding post (black wire), to connect the "wire antenna" to the balun black wire.
The 300 ohm balanced feeder connects to the binding posts with the black and white wires. Please see diagrams below.
I have no idea how the dimensions of the G5RV have been arrived at, as it does not correspond to anywhere near a half wave of 40m, I am surprised it works on 40m at all.
I am wondering if it would be better to revert to my original plan of making each half of the dipole 10m long with a slight overlap at the far end.
Advice and comments would be very welcome. I have also posted this on Golborne.
Thanks
Mike
