HP TM 11-6625-2779-14&P - Manual (Page 17)

Model 3555B Section III
Table 3-1. Front, Side and Rear Panel Controls, Indicators and Connectors (Cont’d)
2. 135: Selects the input circuitry for 135
ohm balanced circuits. A high
frequency transformer is selected for
this function.
3. 75: Selects the input circuitry for 75
ohm unbalanced operation. Only the
75 ohm jack can be used for this
function. This function does not utilize
an input transformer, therefore the
maximum bandwidth is available on
this function. This jack accepts a 358
plug.
(10) DIAL/AC MON: A set of multiple jacks accepting
Western Electric type 310 or 347 plugs, 289 dual
plugs and a pair of special clip posts marked T and
R which accept a Western Electric 1011IB
lineman's handset for the dial and talk operation
when the FUNCTION pushbutton marked
DIAL/BAT is depressed. Loop dialing is used and
the circuit must supply talk battery. When any
other FUNCTION pushbutton is depressed, the tip
and ring of these jacks are connected to the AC
MON output of the internal amplifiers for
monitoring purposes.
(11) DC MON: Accepts a Western Electric 310 or 347
plug for tip negative and sleeve connections to an
external dc recorder. Output voltage is
proportional to the input voltage on any one setting
of the RANGE switch.
(12) INPUT: A set of multiple jacks accepting Western
Electric 241 (or 289), 309, 310 and 358 plugs and a
pair of binding posts marked T and R for banana
plugs, spade lugs, phone tips or bare wires
providing connection to the input circuitry of the
measuring set. When the DIAL BAT pushbutton is
depressed, the INPUT jacks are connected in
parallel with the DIAL/AC MON jacks.
(13) Battery Cover: Removeable by four 1/4 turn screw
fasteners to expose the internal battery for
replacement.
(14) 48V 310: A jack accepting a Western Electric 310
plug with tip negative and sleeve ground to supply
external office battery power to the set. Insertion
of a 310 plug into this jack disconnects the internal
battery. The BAT-AC switch (16) must be set to
BAT for office battery operation.
CAUTION
WHEN OPERATING FROM AN EXTERNAL
BATTERY, CORD SHOULD BE CONNECTED
TO MEASURING SET FIRST, THEN PLUG
INTO BATTERY SUPPLY TO AVOID
SHORTING THE OFFICE BATTERY.
(15) 0.15A-SPARE Fuse: A 0.15A slo-blo fuse and a
spare for measuring set protection when operating
from AC power. Fuses are not used when the set
is battery powered.
(16) BAT-AC Switch: A slide switch for selecting the ac
power source or the internal battery and office
battery jack, (14), power source. The switch may
be operated by a small screwdriver or pointed tool
inserted into the slot in the switch.
(17) AC Power Receptacle: A 3 prong power receptacle
for the special power cord stored inside the front
cover. The BAT-AC switch (16), must be
positioned to AC for this power source.
3-11. High storage temperature is damaging to dry
cells and tends to reduce shelf life. Low storage
temperature is beneficial to battery life although the
battery should be warmed to room temperature prior to
use. Turning off the set when not in use and
consideration of the above factors will maximize battery
life. The instant turn characteristics of this set with no
warm-up time required allows turning off between
measurements.
NOTE
If the battery voltage indication drops below
the left end of the arc on the meter face the
set will not operate properly. This will be
noted by a slow oscillation of the meter. If
this symptom is encountered, depress the
DIAL/BAT pushbutton and check the battery
condition. If the indication is to the left of
the arc on the meter face, replace the
battery.
3-12. LEVEL AND NOISE MEASUREMENTS.
3-13. Since the 3555B is both a level measuring set
and a noise measuring set, the procedure for making
these measurements will be treated separately. Level
measurements can be made at voice frequencies and
carrier frequencies. Since the procedure for making
voice and Carrier level measurements are identical
except for the FUNCTION pushbutton utilized, only one
procedure will be described in detail.
3-14. LEVEL MEASUREMENTS.
3-15. The 3555B can be used as a wide range and
wide
3-5