Phone Operating on HF

Which sideband, and why

One rule with one exception, and the pool asks it four times.

The dividing line falls around 10 MHz: below it, LSB; above it, USB.

Why do most amateur stations use lower sideband on the 160-, 75-, and 40-meter bands?

It is commonly accepted amateur practice.

Convention, not rule. There is no technical reason and no regulation — early equipment made it convenient, and it stuck. Using the wrong one is legal and renders your voice unintelligible, which is the practical enforcement.

Why SSB rather than AM or FM

Which mode of voice communication is most commonly used on the HF amateur bands?

Single sideband.

Which of the following statements is true of single sideband (SSB)?

Only one sideband is transmitted; the other sideband and carrier are suppressed

Which of the following is an advantage of using single sideband, as compared to other analog voice modes on the HF amateur bands?

Less bandwidth used and greater power efficiency

Both halves matter. AM transmits a carrier plus two identical sidebands: two thirds of the power goes into the carrier, which carries no information, and the duplicate sideband wastes bandwidth. SSB throws away both and puts everything into the one sideband that matters — about a third of the bandwidth and a large improvement in effective power.

Setting ALC

What control is typically adjusted for proper ALC setting on a single sideband transceiver?

Transmit audio or microphone gain.

Automatic Level Control limits drive to keep the transmitter linear. It is a safety net, not an operating control: the correct setting has ALC just barely indicating on voice peaks.

Turn the microphone gain up until ALC shows heavy action and you are driving the transmitter into distortion — flat-topping, splatter, and a signal that is wider and less readable, not louder. Reduce it until ALC only flickers.

This is the single most common self-inflicted signal problem on HF.

Breaking in

What is the recommended way to break into a phone contact?

Say your call sign once.

Once. Not “break”, not “break break”, not your call sign three times. One call sign, in a gap, and then wait.

VOX

Which of the following statements is true of VOX operation versus PTT operation?

It allows “hands free” operation.

That is the advantage; the disadvantages are worth knowing too. VOX triggers on room noise, clips the first syllable while it decides, and holds the transmitter up during pauses. It is excellent for a quiet room and mobile operating, and poor in a noisy one.

DX etiquette

Generally, who should respond to a station in the contiguous 48 states calling “CQ DX”?

Any stations outside the lower 48 states.

“CQ DX” means the caller wants distance, and answering from three states away wastes everyone’s time — including yours, since they will not work you.

The corresponding band-plan convention:

What is the voluntary band plan restriction for US stations transmitting within the 48 contiguous states in the 50.1 MHz to 50.125 MHz band segment?

Only contacts with stations not within the 48 contiguous states.

That 25 kHz at the bottom of 6 metres is reserved by voluntary agreement for DX work. Domestic contacts there are legal and antisocial — exactly the character of every band plan.

Check yourself

1. You are on 7.200 MHz for a voice contact. Which sideband?
2. Your ALC meter pins on every syllable. What is happening and what do you adjust?
3. A station in Ohio calls “CQ DX”. Should you answer from Michigan?