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Suppressing noise on prototype HF rig.
Ferrite choke suppressing noise.

This video demonstrates the use of a split tube ferrite choke to suppress some noise on the AGC line of a prototype HF rig. This is breadboard layout of a 3 band HF transceiver using a PLL module VFO, with A and B vfo selection, controlled by an Arduino Mega. The particular noise only shows up when the antenna is disconnected and the receiver is at full gain, and only on the 20 metre band. The use of the choke is a quick way of finding noise in various parts of the prototype. Later, when the modules are mounted in the final enclosure, the noise will most probably go away. If not then a closer look is needed .