![]() Therefore when the signal at G1 is 144 MHz, and TR2 is adjusted to oscillate at frequency of 116 MHz, the output is set at 144 MHz - 116 MHz = 28 MHz. ![]() The output frequency from the TR1 drain which forms the mixer stage causes the difference between frequencies of G1 and G2. Oscillator function is implemented via C3 on the gate 2 of FET TR1. TR2 works like the local oscillator, and the functioning frequency in this design is fixed through the inductor L2 and trimmer T2. ![]() L1 is roughly tuned to the desired frequency band through T1, to enable the signal input to reach the gate 1 of FET TR1. Considering the fact that at this frequency the RF amplifier may not add a great deal of gain, and that tunable VHF oscillators are widely-used in numerous household VHF receivers, a much simpler circuit shown below can actually be very handy. ![]() This enables substantial sensitivity and superb frequency stability, although is a somewhat complex and costly product. In most 2 metre band ham receivers, the reception of the RF signals is generally implemented through a converter and short wave receiver, ideally suited to communications type.Ī converter of this type usually comes with its personal RF amplifier, along with a fairly low frequency crystal controlled oscillator, accompanied by frequency multipliers.
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