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“The nutty antennas are the ones that get my interest, and Isotron has been accused of being “nutty”, or at least it has been treated skeptically by some.”
Usually the accusation, or treatment of skepticism towards the Isotron is from those who have not even tried one, or built one. Just a lot of baseless…well accusation and skepticism.
An Isotron is a large LC resonant tank circuit, not all that different from a conventional monopole with a loading coil and ground radial system. In fact, place a cap hat on top of a 3 meter monopole which sits over a ground radial system and you pretty much got the same thing as an Isotron. The cap hat is your top plate, the monopole radiator and loading coil is the center part, and the ground radial system is the lower plate.
The name itself describes the Isotron’s intent. It is an antenna designed for self contained resonance capability without the need of a ground system, which is perfect for situations where access to the dirt is hindered, such as in a hi rise building/apartment or nothing but concrete below.
It requires no coax and is not designed or intended to use a coax..so please all you coax will radiate blah blah’s put that worn out broken record away because the Part 15 MW Isotron is NOT DESIGNED or INTENDED to have a coax!!
The Part 15 MW Isotron is designed to have the transmitter at the base of the antenna, just like a conventional 3 meter monopole system has the transmitter at the base of the antenna system. And again, the Isotron is designed to function with no ground radial system whatsoever.
It works incredibly well versus a plain old loaded up piece of wire, and somewhat more rigid too, meaning it wont swing and ding-a-ling with the air from the circulating fan in the room.
In an outdoor setup, the Isotron works best elevated and side mounted to it’s support structure as well as isolated electrically from that support structure. NO ELECTRICAL CONNECTION!!!
I used a home built Isotron very similar to the one I described above with an SSTran AMT3K purchased off ebay and did the modifications on the SSTran website to configure it for 50 ohm load matching. The signal penetrated through the apartment building and over into the surrounding apartment buildings far better than the simple wire setup using that same transmitter when it was configured for loading up to a wire and using it’s internal matching network, and even when using an external loading/matching network after bypassing the internal network.
The home brew Isotron is only different from the manufactured one in that the top plate in the home brew unit does not have a tunable top plate section, thus the reason for the tuning cap and tap along the lower portion of the coil. My next home brew unit will have a tunable top plate using a piece of fiberglass rod and a lock down clamp so that the top plate and connection can raise and lower, as well as the taps and tuning cap on the lower portion of the coil for further peaking.
I suggest to those who find their skepticism and accusation taking over their minds to build one or buy the manufactured Isotron and try it. Connect it as described and don’t try to cook the books by connecting it improperly or improperly tuning it. It deserves far better treatment from those who have not even taken that baby step of actually using one.
I’ve used it in those impossible to access dirt ground situations and found it to be very effective compared to the simple dangling wire. You will too.