A simple experimental radio transmitter operating at 3.57 MHz. Output power is approximately 1.2 W with a 12 V supply. It's called experimental because I decided to test whether it was possible to drive a cheap IRF630 transistor with a single 4093 chip. Succeeded, and the 4093 chip is quite capable of driving the IRF630 gate at 3.57 MHz.
The antenna and counterpoise are 6 meters long and made from regular wire. L3 is wound on a 16 mm diameter former and contains 55 turns of 0.4 mm wire. A ferrite rod is inserted into the coil to tune the antenna to resonance at the desired frequency. NANOvna showed an SWR of 1.2.
To minimize the high-frequency signal coming from the transmitter to the power supply, a power supply choke is required. This is a common-mode choke from a household appliance, wound on a green ferrite ring.
L1 and L2 are wound on 16 mm diameter formers and contain 20 turns of 0.4 mm diameter wire each.
I walked 500 meters away from the house and received the transmitter's signal on the radio receiver, while the receiver's antenna was retracted. The second harmonic at a frequency of 7156 kHz was received at a distance of 150 meters from the house.
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