A receiving converter for 2320 MHz

Posted on Feb 5, 2014

The preamplifier is very simple. I used a Low Noise integrated circuit manufactured by Hewlett Packard. The device name is MGA86563. It has a Noise Figure of about 2dB and can be used from 0. 5 GHz to at least 6 GHz. The gain is about 20-22dB at 2. 3 GHz. The input and output ports are internally matched to 50 Ohms. All you have to do is to put a ca

A receiving converter for 2320 MHz
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pacitor in front of the device and behind it and provide the necessary supply voltage of 5-7 Volts at the output port. I used a quarterwave stripline for the supply voltage. The 100 Ohms resistor is used to "de-Q" the circuit in order to avoid oscillations. This resistor causes a voltage drop that must be equalized by a somewhat higher supply voltage of 7. 5 Volts. (Fig. 2) The harmonic mixer is not much more than two Schottky Diodes BA481. They short circuit the signal twice at every periode of the LO signal (at every half-wave). At the input there is a bandpass filter to suppress the image frequency. A monolitic amplifier ERA 3 from Mini Circuits (New York) amplifies the signal for another 20dB. This is not necessary in order to have an optimal sensitivity (the preamp would be sufficient without another amplifier) but it helps to have a strong signal at 144 MHz. This allows you to put the converter at the antenna and use a cheap coax cable for the IF. A 144 MHz amplifier at the output is not advisible because strong 144MHz-signals from the neighborhood could get into the amplifier and then cause interference to your 13cm signal. The LC-transformation-circuit at the output makes sure that the mixer is not overloaded by the 50 Ohms of the IF receiver. (Fig. 3) I will not give the circuit diagram for the 1088 MHz local oscillator. It is really not adviceable the way I did it (now I know!). I built a 1088 MHz VCO and...

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