Controls, Connectors And Indicators; Front Panel - HP 4937A Operating And Service Manual

3-15. CONTROLS. CONNECTORS, and INDICATORS
MODEL 4937A
CONTROLS
FRONT PANEL
1
Power Switch--Swiiches power to the instrument when in the ON position. In the STBY position
Dower
IS
stiit applied to some circuits, it the unit has the battery (Option 001) there will stiii be
power available to some interna! circuits even in STBY position and the batteries are charged in
this position. There are separate battery operation and low battery indicators. These indicators
are located in the left hand display.
2, DISPLAY key—Selects either the TRMT (transmit) or the RCV (receive) signal to be displayed,
The corresponding LED will be lighted.
3. RANGE HOLD and SF SKIP key
RANGE HOLD--Prevents the autorange from changing from its present setting during a
measurement.
3
P skip--Prevents the transmitter from transmitting within +
This feature eliminates accidentally being disconnected by
Operates only in LEVEL/FREQUENCY.
-1
50 Hz (300 Hz band) of 2600 Hz.
SF signaling units on dial-up lines.
4 LEVEL ZERO key--Sets a 0 dB reference in RCV LEVEL/FREQUENCY mode. All subsequent
measurements will be made in dB relative to this reference. dB LED in center of the front panel
will light, A - (minus) dB reading indicates levels higher than the reference level per the telephone
industry convention.
wire return loss and RCV mode, the LEVEL ZERO key enters a 0 dB return loss in the left
and calculates the transhybrid loss (THL) which is displayed in the right hand display.
display
5 3
JEP yp_ STEP DOWN, <- and -> keys--in TRMT Mode (right display) and LEVEL FREQUENCY;
<- or -> selects the position of digit to be increased or decreased. Lighted cursor indicates
one-of-four digit positions. Digit value is incremented by pressing STEP UP and decremented by
pressing STEP DOWN. Pressing and holding the STEP UP or STEP DOWN key causes the action
to repeat, Also, with the SHIFT key sets the output frequency to 404 Hz, 1004 Hz, 2804 Hz, and
2713 Hz in LEVEL FREQUENCY mode.
in 4-wire return loss and RCV mode, these keys are used to enter the THL of the circuit,
6
OUTPUT LEVEL Control-"Adjusts the transmitter output level continousty from -40 dBm to +13
dBm,
Output
level is displayed
on
the left display.
7. SHIFT key""Used to activate any of the functions labeled in blue.
8
. MONITOR VOLUME Control and Speaker--Permits adjustable volume for listening to the circuit
under test or to the Test Set Transmitter.
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