Drake 300VMF+ Fixed Modulator - Manual (Page 5)

R1 - VIDEO INPUT Connector
This is the baseband video input to the IF circuits. This
input accepts baseband through 4.2 MHz video at levels
from 0.7 Vp-p to 1.5 Vp-p
.
R2 - AUDIO INPUT Connector
This is an unbalanced audio input to the IF circuits. This
input accepts 40 Hz through 15 kHz audio at a nominal
level of 250 mV RMS (approximately -10 dBu).
If a separate BTSC stereo encoder, such as the Drake
MMTS20, is to be used with this modulator, this jack can
input 40 Hz through over 50 kHz with fl at response if
internal jumper J8 is set to fl at - see below)
R3 - RF OUTPUT
This is the modulator output.
INTERNAL JUMPER SETTING - AUDIO RESPONSE
Internal jumper J8 may be used to disable the 75 uSec
pre-emphasis (normal setting). Flat response may be
chosen if an external BTSC stereo signal is to be input to
the modulator through the audio input jack. To access this
jumper, disconnect the unit from AC power. Remove the
three screws holding the top cover of the chassis in place.
Remove top cover. J8 is a three pin header with J8
printed on the PCB. After setting this jumper, reinstall the
cover before returning power to the unit.
NORMAL RESPONSE of 75 uSec = Jumper in the 1-2
position (shorting pins 1 and 2 of the J8 header). Use this
setting for normal mono audio input. This is the factory
default setting.
FLAT RESPONSE = Jumper in the 2-3 position (shorting
pins 2 and 3 of header J8). Change to this setting when
an external BTSC stereo encoder is used with the
300VMF+.
R4 - AC OUTLET Receptacle
This is a power receptacle for other equipment and is
rated at 600 W maximum; 120 V, 5 Amp. This receptacle
is unfused and unswitched.
R5 - LINE CORD
This is a three-wire power cable. When the cable is
connected to a properly wired AC power line outlet, this
cable grounds the instrument cabinet. Connect to a
115 VAC ±10%, 60 Hz source. Do not defeat the safety
purpose of the attached line cord plug.
Rear Panel Description and Internal Jumper 5
R1 R2 R3 R4 R5