
®
Telex
Description and Wiring Diagrams
Model PH-3500 Headset (300623 Series)
General Description
The Telex PH-3500 is a passive noise attenuating headset for use in a noisy environment. Dual controls allow 
the user to individually adjust the volume level for each 
ear. Using the latest design and modeling techniques, Telex 
has been able to maximize the amount of hearing protection provided by the PH-3500, while at the same 
time minimizing weight. The PH-3500 has a noise reduction rating of 24 dB, and is suitable for use in noisy 
environments. The PH-3500 features a unique headband 
design that provides comfort for long periods of time. 
Two versions of the PH-3500 are available: with a male 
or female XLR4 connector.
Design Features
Comfortable foam-filled headband pad and ear cushions. The headband pad evenly distributes the headset weight, with no pressure 
points, for maximum comfort. The ear cushions combine comfort and light weight with an excellent acoustic seal. An outer urethane 
layer ensures long life. Gel-filled ear cushions are also available for this headset for users who prefer this type. All cushions are fieldreplaceable.
Boom Microphone: The boom arm features a sealed ball-and-socket joint and flexible boom for precise microphone placement 
on any head size. The boom and cord rotate for microphone placement on either side of the head. The microphone cartridge is an 
electret condensor element. The microphone housing and cartridge are easily removed for replacement.
Cordage: The microphone cordage is protected inside the boom arm. Shielded wire throughout the headset protects against RFI 
and EMI. Strain-reliefs on all cords provide maximum durability.
Operation
Headband Pressure Adjustments
There are three pressure settings. Increasing the pressure will improve the seal between the earcup and the head for greater noise 
reduction. To change the pressure setting, remove the headset and fold the earcup inward as shown, then rotate the adjustment 
knob to the desired setting. Repeat for both earcups. Both sides of the headband should be set to the same pressure setting to keep
the headband properly centered on the head.
HIGH MEDIUM LOW

PH-3500 Headset
Connectors
RED
SPEAKERS
WHT
+ 
R
BLK
5000 OHM
WHT/OVERHEAD
SHIELD/OVERHEAD
MICROPHONE
CW ROTATION 
INCREASES GAIN
WHT
+
L 
BLK
5000 OHM
SHIELD
+
–
NC
CCW ROTATION 
INCREASES GAIN
RED
BLK
SHIELD
RED
BLK
SHIELD
WHT
BLU
SHIELD
BLK
SHIELD (Microphone)
BLU
WHT
SHIELD (Speakers)
12K
1/8W
300623-001
Audiocom Compatible
1
2
/ 300623-002
4
XLR4
3
SPECIFICATIONS
Receivers:
Type: Dynamic 
Frequency Response: 350 Hz - 3.0 kHz ±6 dB (150 S at max. volume) 
Sensitivity: 90 ±5 dB SPL (1 kHz, 1 mW input)
Microphone and Amplifier:
Element Type: Noise-canceling electret condenser 
Frequency Response: 100 Hz - 3.5 kHz 
Sensitivity: -53 +2/-1 dB (ref:1 V/µbar) 
Output Impedance: 50 ohms (designed for intercom input impedances 
from 50 - 600 ohms) 
Operating Voltage: 8 - 30 Vdc
Cordage:
Straight cord, 5 ft. (1.5 m)
Connectors:
4 pin XLR male or female XLR4 connector
Weight:
Gross Weight: Approx 13.6 oz. (385 g)
Color: Satin black
ORDERING INFORMATION
Description Catalog No.
PH-3500 Double sided w/boom, 4 pin female XLR connector .............................................................................................................. 300623-001
PH-3500 Double sided w/boom, 1/4” stereo phone plug....................................................................................................................... 300623-002
Foam Ear Cushions (set of 2) ................................................................................................................................................................. 800147-001
Gel-filled Ear Cushions (set of 2) ............................................................................................................................................................ 800027-002
Replacement Head Pad .......................................................................................................................................................................... 800146-000
Replacement Microphone Housing Assembly ........................................................................................................................................ 800136-002
Windscreen ............................................................................................................................................................................................... 57012-001
®
38109-721 Rev B 5/05