Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-003-002
In a simple 2 stage CW transmitter, current to the collector of the transistor in the class C amplifier stage flows through a radio frequency choke (RFC) and a tapped inductor. The RFC, on the tapped inductor side, is also connected to grounded capacitors. The purpose of the RFC and capacitors is to:
- Aprovide negative feedback
- Bform a key-click filter
- Cform a RF-tuned circuit
- Dform a low-pass filter
Correct answer: D — form a low-pass filter. From the official ISED question bank, verified word for word.
Why
An RF choke blocks high-frequency signals while letting direct current pass, and when paired with grounded capacitors, it creates a path that shunts unwanted high-frequency harmonics to ground. The full explanation — and one for every question — is in Pro.
Practise this section
Transmitters, modulation and processing is section A-005 of the Advanced exam: Transmitters, modulation and processing: AM, FM, SSB, keying, speech processing, and the numbers behind occupied bandwidth.
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