Portable antenna tuning devices/approaches
Nearly any antenna in use today requires or benefits from a tuner. Single or multiband dipoles are of course an exception as are some other dedicated antennas specifically designed for one or several bands. But most ham shacks today have one or more tuners. My primary tuner in the shack these days is an LDG Z11Pro II which will handle just about anything I throw at it. I also have several manual tuners, most on the shelf and only get used occasionally. The first portable tuner I had and still have is the MFJ -971. It is a wonderful little tuner and more than suitable for a drive up portable setup. But its size and weight make it a less suitable tuner for a long backpacking trip, though its versatility is enviable.
The two that I'll be playing mostly with in preparing for our summer 2015 six day backpacking trip to Glacier National Park are a home built parallel tuned transformer for end fed half waves for 40 and 20 meters and the Tuna Tunah ii by QRPme.
The two that I'll be playing mostly with in preparing for our summer 2015 six day backpacking trip to Glacier National Park are a home built parallel tuned transformer for end fed half waves for 40 and 20 meters and the Tuna Tunah ii by QRPme.
Tuna Tunah iiFrom what I am learning while using this tuner it is quite versatile and can handle a surprising range of antenna impedance. It takes a little patience and persistence to find the right combination of switches but I have yet to find anything it won't tune!
If you compare the photo at right with the official photo QRPme's website you'll notice the additional switch mounted just to the right of the mounting nut in the middle. It allows me to switch in additional capacitance across the built in variable capacitor. I added it a year or so ago when playing with end fed half wave antennas. So far this year I have not found it useful! The switched conductors have allowed met o tune anything I've connected so far. Another alteration was replacement of the provided RCA connectors for transmitter and antenna with BNC connectors. I don't have any coaxial cables with RCA connectors on them so they were a major inconvenience. Not sure why the manufacture used them as they are rare in ham radio for antenna connections especially. |
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Parallel Tuned Transformer for End Fed Half Wave Wire Antenna
For details of this approach I suggest the the website by M0UKD. My version of this is described on my end fed half wave antenna page.
