Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-002-002
The purpose of using a centre-tap return connection on the secondary of transmitting tube's filament transformer is to:
- Akeep the output voltage constant with varying load
- Bobtain optimum power output
- Cprevent modulation of the emitted wave by the alternating current filament supply
- Dreduce the possibility of harmonic emissions
Correct answer: C — prevent modulation of the emitted wave by the alternating current filament supply. From the official ISED question bank, verified word for word.
Why
The centre tap on the filament transformer balances the alternating current so it does not create an unwanted audio signal that gets mixed into your radio wave, which would sound like a buzzing hum in the received signal. 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.
Drill A-005 — free, no account