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VLF The stealth antenna
the passion for radio listening on HF and lower band, down to VLF
post 31 Jan 2024
Antenna 136KHz Links →
137 Khz CW transmitter
This is the TX freq logic, using a 27Mhz CB xtal and dividers to generate the 136 Khz The 27.407 Mhz is divides by 2 and then later by 10 in two 7493 counters then the 1.37035Mhz is feed into a 4017 decade counter, this one divide the freq by 10 again,Now the output freq is 137.035 Khz, the smart thing about the 4017 is that I can use the 10 outputs to generate the two outputs to my push-pull stage epending on how meny outputs used the pulse width can also be controlled
137kHz qrss rtx
Building a low-IF receiver using a LO at 135.42kHz and an high dynamics mixer
137 kHz experimental station
HiPerFET Power MOSFET IXFN55N50 500 volts at 55 amps, Currently running 28Volts at 14 amps input, Output 265 Watts
200W 136 kHz transmitter
My first transmission experiments on 136 kHz band where based on a little TX build around surplus component
600 Meter (VLF) Experiments as WD2XSH/22 ANTENNAS
The grey metal box at the bottom of the loop houses the tuning capacitor bank and the ferrite core matching transformer
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This is the TX freq logic, using a 27Mhz CB xtal and dividers to generate the 136 Khz The 27.407 Mhz is divides by 2 and then later by 10 in two 7493 counters then the 1.37035Mhz is feed into a 4017 decade counter, this one divide the freq by 10 again,Now the output freq is 137.035 Khz, the smart thing about the 4017 is that I can use the 10 outputs to generate the two outputs to my push-pull stage epending on how meny outputs used the pulse width can also be controlled
Building a low-IF receiver using a LO at 135.42kHz and an high dynamics mixer
HiPerFET Power MOSFET IXFN55N50 500 volts at 55 amps, Currently running 28Volts at 14 amps input, Output 265 Watts
My first transmission experiments on 136 kHz band where based on a little TX build around surplus component
The grey metal box at the bottom of the loop houses the tuning capacitor bank and the ferrite core matching transformer
Take off angle of horizontal antenna For horizontal polarization, the electric field will move sideways on a horizontal plane, while for vertical polarization it will oscillate up and down on a vertical plane
Rx antennas 4Square Rx Vertical Array My frequency design of 1.825 MHz a 90 degrees line would be 33,70 metersinstead of the previously calculated 33,27 m
Calculo da Antena Bazooka A double bazooka antenna is a combination that has a complete coaxial wave multiplied by its velocity factor and a total end-to-end length of 1/4 wave for each side affected by another driver shortening facto