Total posts : 45366
Radio Joe’s use of the word “coax” is confusing to me because Part 15 AM transmitter designs usually do not use coax, since any transmission line counts toward the 3 meter length budget in Section 15.219(b). I took Joe’s word “coax” to simply mean the transmitter output. Optional outdoor antennas using coax (for real-estate transmitters) have been discussed in this Forum, and their legality under 15.219(b) has been questioned.
In my previous post, I said that a high-voltage transmitter output is needed to drive the loading coil and antenna capacitance in parallel. To clarify, I will add that the transmitter output has to have high impedance, also. The transmitter output has to approximate a current source.
Using the loading coil in a step-up transformer configuration also increases the voltage across the loading coil, as Neil noted. A step-up transformer is used in the Rangemaster, for example. I was responding to whether the transmitter can be connected to the hot side of a grounded loading coil, so I did not mention transformers.