What is the preamp, What is the break-in function, Panel description – Icom IC-756 User Manual

Page 6

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BAL

COMP

KEY SPEED BK-IN DELAY

APF

LOCK

AUTO NOTCH

TWIN PBT

CW PITCH

F-1

SSB

F-2

F-3

F-4

F-5

SPEECH

LOCK

RIT/

RIT

CLEAR

RTTY

SPLIT

MP-W

MP-R

DUAL

WATCH

VFO/

MEMO

MAIN/

SUB

CHANGE

1.8

3.5

24.5 8

GENE

F-INP

ENT

M-CL

XFC

i756

1ß

VFO

14.195.000

VFO

USB

14.100.00

14.205.000

USB

14.100.00

T X

FILTER

SCAN

MEMORY

SET

VOX

VOX
OFF

OFF

COMP

COMP
OFF

OFF

SCOPE

ANT

METER

P.AMP

OFF

ATT

ATT
OFF

OFF

AGC

AGC
MID

MID

2.4k

2.8k

455

12:34

MULTI-FUNCTION SWITCHES
• Push to select the functions indicated in the LCD

display to the right of these switches.

- Functions vary depending on the operating condition.

• Push to input a character for memory keyer pro-

gramming or memory name. (pgs. 36, 45)

• Toggles the antenna connector selection

between ANT1/R and ANT2/R when
pushed. (p. 37)

• Toggles the receive antenna ON and OFF

when pushed for 2 sec.

• Selects RF power (Po), SWR or ALC me-

tering during transmit. (p. 34)

• Selects one of 2 receive RF preamps or

bypasses them.

- “P. AMP1” activates 10 dB preamp for HF all

bands.

- “P. AMP2” activates 16 dB high-gain preamp

for 21 MHz band and above.

✔

What is the preamp?

The preamp amplifies received signals in the front end cir-
cuit to improve the S/N ratio and sensitivity. Select
“P. AMP1” or “P. AMP2” when receiving weak signals.

• Selects 6 dB, 12 dB or 18 dB attenuator,

or bypasses them.

✔

What is the attenuator?

The attenuator prevents a desired signal from distorting
when very strong signals are near the desired frequency
or when very strong electric fields, such as from a broad-
casting station, are near your location.

• Activates or selects fast, middle or slow

AGC time constant when pushed.

- The setting becomes “fast” in FM mode re-

gardless of this setting.

• Deactivates the AGC circuit when pushed

for 2 sec.

NOTE: While “AGC OFF” is selected, the
S-meter does not function.

✔

What is the AGC?

The AGC controls receiver gain to produce a constant
audio output level even when the received signal strength
is varied by fading, etc. Select “FAST” for tuning and se-
lect “MID” or “SLOW” depending on the receiving condi-
tion.

• Turns the VOX function ON and OFF when

pushed in non-CW modes. (p. 33)

• Enters the VOX set mode when pushed for

2 sec. in non-CW modes. (p. 33)

• Selects semi break-in, full break-in opera-

tion, or turns the break-in operation OFF
when pushed in CW mode.

✔

What is the VOX function?

The VOX function (voice operated transmission) starts
transmission without pushing the transmit switch or PTT
switch when you speak into the microphone; then, auto-
matically returns to receive when you stop speaking.

✔

What is the break-in function?

The break-in function toggles transmit and receive with
CW keying. Full break-in (QSK) can monitor the receive
signal during keying.

VOX