Technical Details

A lot of cell phones use a GSM800 mobile standard in order to operate, so my VCO (sweeping oscillator) is tuned to the 800MHz frequency range. Keep in mind that it could be difficult to make this  work properly without some good testing tools, but the end result will have the efficient VCO.

Use a clock oscillator for 45MHz as the noise generator for this jammer. It drives the local oscillator port which is located at the mixer. The signal is going out from the local oscillator and passes through the impedance matching network along its way. This helps equalize the impedance of 45MHz clock oscillator with the impedance of the mixer’s port.

This port acts like RF input of the signal jammer. The RF output signal passes through the amplifier on the mini-circuit. The output power is increased by additional 15-16dbm in this way. Then the output signal goes to the RF output antenna. RF input has the antenna too.

Jammer Operating

Use a 45MHz clock oscillator because the GSM800 band transmitted and received signals are always separated by the exact number of frequency and it is that 45MHz. Take this into account, cell phone user dials someone and signal goes off. RF input antenna catches it and jammer modifies this signal and lets it go. This signal has a frequency of cell phone’s received signal, so cell phone user would hear their own voice in a phone!

This particular cell phone jammer might be used to block the signal of the cell-based car tracking device which records your GPS data and sends it to some other person. And it probably can even jam some IED signals if they are controlled by cell phone GSM800 band.

The used mixer was originally made for 600MHz but with a little modification it works perfectly for 800MHz.

The amplifier is great for output power. Although it draws additional power supply, it is worth it.

Jammer case was made from old aluminum box and UHF connectors you can take from an old Motorola phone.

Those connectors must be soldered to the mini-circuit to work properly.

To supply this little signal jammer the nine volts battery with voltage regulator is enough. Separate it from other electronic components with foam plastic.

Don’t forget to make a power switch for your new creation. Also remember to attach antennas to the UHF connectors.