You are able to hear signals in the SITOR...

🔍 Key Concepts

• Difference between RF (radio frequency) stages and audio stages in a receiver • How SITOR/NBDP demodulation uses narrow filters and a terminal, versus voice/SSB, which requires the audio chain and BFO for intelligible sound • What a failure in the RF amplifier would affect compared to failures in audio-related components

💭 Think About

• If you can copy SITOR/NBDP data but cannot hear voice, which parts of the receiver chain must still be working? • Which component failure would affect both data and voice, and which would only affect what you hear as audio? • How does a defective audio amplifier or audio‑related filter show up in terms of what you can or cannot monitor with your ears?

✅ Before You Answer

• Identify which stages are common to both SITOR and voice reception (antenna, RF amp, mixer, IF stages, etc.) • Identify which stages are used differently or bypassed when decoding SITOR/NBDP versus listening to voice/SSB (audio amplifier, speaker, certain filters) • Check which single failed component listed would still allow SITOR/NBDP decoding but prevent you from copying voice by ear

You are able to hear signals in the SITOR (NBDP) mode but not in the voice/SSB mode. What is the most likely cause?

The B.F.O. circuit has failed.

The audio amplifier is defective.

The 2.8 kHz filter has become defective.

The R.F. amplifier has failed.

🔍 Key Concepts

💭 Think About

✅ Before You Answer