Kenwood TS-780 manual 5-6VOX OPERATION, 5-7READING THE FREQUENCIES, 5-8BAND SWITCH UP-DOWN

5-6 VOX OPERATION

The VOX is an automatic switching System that swit- ches the transceiver to transmit and receive while speaking into the microphone. This is mainly used in SSB mode.

With the VOX switch set to ON, the transceiver is automatically switched to transmit mode when you speak into the microphone and to receive mode when you stop talking. For VOX Operation, the standby switch should be set to REC.

Control Settings

1.Adjustment of VOX GAIN Control

With

the

standby

switch

set to REC, place the VOX

switch in the VOX (ON) Position.

First turn the VOX GAIN control

clockwise

and adjust it

so

that

the transceiver

is switched to transmit mode

when you speak into the microphone with normal voice.

Turn

the

control

further

clockwise and the gain is

increased allowing the transceiver to be switched to

transmit mode with a lower level

of

voice. However,

excessive VOX gain results in misoperation by ambient

noise.

The condition

of VOX Operation

can be checked through

the speaker. When any

Sound is heard from the speaker,

it means that the transceiver is in receive mode; other-

wise, it is in transmit mode. In

transmit mode, the ON

AIR indicator Comes on and, in receive mode, the light of

indicator

goes

off.

2. Adjustment of ANTI VOX GAIN Control

This control is located on

top of

the

case

(sec page 9)

and is used to prevent the VOX circuit from being

misoperated by the Sound of speaker.

Adjust the VOX GAIN control as directed in item (1)

above. Then, adjust the AF GAIN control for suitable

volume

while receiving Signals

from

a

Station.

Hold the microphone 20~

30 cm from the speaker and

adjust the ANTI VOX GAIN control until speaker Sound

will

not

activate

the

VOX circuit.

Excessive

turning of

the

control in

clockwise

direction

will Cause the ANTI

VOX circuit to operate, resulting in failure of the

transceiver to

be

switched to transmit

mode.

3. Adjustment of VOX DELAY Control

This control is used to hold the transmitter on after VOX

Operation. If the hold time is

too short, the TS-780

returns to receive whenever you pause speaking. If too

long, the TS-780 will not

return to receive after speak-

ing. Adjust the control so that the transceiver holds pro-

per transmitting time when you speak at normal Speed.

This control is also effective

for

CW

semi-break-in

Operation.

During

CW Operation,

do

notturn the control excessive-

ly in clockwise

direction,

as it takes a long time until the

transceiver returns to receive when the key is released;

making

it

impossible

to

perform

smooth

semi-break-in

Operation.

Note:

If the VOX switch is left ON, the TS-780 will momen- tarily transmit when the POWER switch is turned on. After VOX Operation, set the VOX switch to OFF.

5-7 READING THE FREQUENCIES

The TS-780 digital display indicates	carrier positions in
all operating modes. Because of the use	of a special circuit,

the carrier Position remains the same when the MODE switch is manipulated, thus the transmit and receive fre-

quency can be directly read				on the digital display, except
for	CW reception		where the	frequency on the display is
higher by the beat frequency				(800 Hz: see	section on	“CW
Mode”) than the transmit frequency.
Note:
The	digital	display	does not	indicate the	frequency	varied
by	the RIT	knob.

5-8 BAND SWITCH (UP-DOWN)

The BAND switch consists of two pushbutton switches, UP and DOWN. By pressing the UP switch, the frequency is shifted up by 1 band and, by pressing the DOWN switch the frequency is shifted down by 1 band. By holding either switch down, the frequency is shifted continuously at 0.5 seconds intervals. As shown in the illustration below, the BAND switch functions separately for the VFO A and B (sec section 5- 9 on “Operation of 2 VFO’s). The BAND switch uses feather-tauch pushbutton switches. A tone pulse is heard whenever the switch is pressed.

5-9 DIGITAL VFO

The TS - 780 VFO is designed so that the pulses generated by rotating the VFO knob are counted by the microprocessor to vary the frequency through PLL circuit. The frequency is varied step by Step. The step interval is 20 Hz (SLOW) for CW and SSB Operation or 200 Hz (FAST) for fast-forward and FM Operation. Either step can be selected by the S/F switch (sec section 5-12).

The adjustable range of the digital VFO is shown in Table 1.

	F.STEP switch “OFF”	F.STEP switch “ON”
144 MHz BAND	1 4 4 , 0 0 0 . 0 0 -	1 4 4 , 0 0 0 . 0 0 -
	145,999.98	145.999.80 I
430 MHz BAND	4 3 0 , 0 0 0 . 0 0 -	4 3 0 , 0 0 0 . 0 0 -
	439.999.98	439.999.80

Table 1

Turning the VFO dial in either direction will shift the fre- quency in endless mode between 144 . 000 . 00 and 145.999.98 In the 144 MHz band. The dial also functions similarly in the 430 MHz band. Note that the upper limit of the band varies according to the Position (ON/OFF) of the F. STEP switch or mode.

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