I've made some slight changes to my magnetic loop aerial. Nothing major, but useful none-the-less.
The original design, as copied from G4ILO, featured a T shaped mast with hooks on the left and right of the top bar to support a loop of RG-213 coax. The biggest problem I found with this was establishing the correct loop shape to create a good match. It was easy to squash or expand the loop which could destroy a previously good match.
To overcome this, I've redesigned the mast to a + shape. The same coax is used for the loop but it is now much more rigid than before meaning if I collapse the aerial and re-assemble it later, I am more likely to maintain a good SWR reading.
Other than that, I've now got a large run of RG58 coax to connect the rig to the aerial meaning positioning is much easier. I've also obtained a better fitting knob for the tuning capacitor. The one I was using was too big for the shaft making it off-centre, wobbly and more difficult to tune.
So what do I have still to do? Well G4ILO's design features an inbuilt SWR indicator which I might incorporate although it's not essential for me at the moment.
I'm still thinking about remote motorised control as well although gears seem to be more complicated than I thought. It is only the gears which are the problem though. The capacitor housing is large enough for a motor which will be connected to a long cable run (as long as the RG58) terminating in a small control box which can set next to the radio. All it needs to incorporate is a momentary push button control to activate the motor and perhaps a variable resistor to control the motor speed.
The original design, as copied from G4ILO, featured a T shaped mast with hooks on the left and right of the top bar to support a loop of RG-213 coax. The biggest problem I found with this was establishing the correct loop shape to create a good match. It was easy to squash or expand the loop which could destroy a previously good match.
To overcome this, I've redesigned the mast to a + shape. The same coax is used for the loop but it is now much more rigid than before meaning if I collapse the aerial and re-assemble it later, I am more likely to maintain a good SWR reading.
Other than that, I've now got a large run of RG58 coax to connect the rig to the aerial meaning positioning is much easier. I've also obtained a better fitting knob for the tuning capacitor. The one I was using was too big for the shaft making it off-centre, wobbly and more difficult to tune.
So what do I have still to do? Well G4ILO's design features an inbuilt SWR indicator which I might incorporate although it's not essential for me at the moment.
I'm still thinking about remote motorised control as well although gears seem to be more complicated than I thought. It is only the gears which are the problem though. The capacitor housing is large enough for a motor which will be connected to a long cable run (as long as the RG58) terminating in a small control box which can set next to the radio. All it needs to incorporate is a momentary push button control to activate the motor and perhaps a variable resistor to control the motor speed.