STW3 Two Way Monitoring Kit Instructions
The STW3 is a single zone 2-way Audio Surveillance System for use with all ETS STW1 series microphone / speakers. It
can be used independently for monitoring live audio or with tape recorders for recording and playback.
STW1 Mounting
Locate the STW1 Microphone/Speaker near the area of interest. Do not mount the STW1 near air conditioning vents, light
fixtures or electrical equipment. Try to keep the distance between the STW1 and the STW2 under 1,000 feet.
Cable Run
For the Microphone, run a 22 gauge, 2 conductor shielded cable (1,000 feet maximum length) between the STW1 and the
STW2 base station. Keep the cable away from AC power sources, light fixtures and electrical equipment.
For the Speaker, run a 22 gauge, 2 conductor shielded cable (1,000 feet maximum length) between the STW1 and the
STW2. For the optional Call Switch, a 22 gauge, 2 conductor cable can be used. This is a contact closure type of
connection so it doesn’t matter which side goes where,
Adjusting the STW1 Microphone Gain
On the back of the STW1, near the center of the board, is an adjustment pot labeled “Gain”. Use a small flathead
screwdriver and turn t or – for maximum clarity. If the sound at the amplifer is distorted, rotate towards the –
mark (counter clockwise). If the sound is too low, rotate towards the + mark (clockwise). Be careful not to move the pot too
far in either direction.
Setting the STW1 Jumpers
The STW1 Microphone has jumper selectable treble boost and limiter circuits. The treble boost circuit emphasizes the
high frequency sounds that the Microphone picks up. This is useful for improving the sound quality on slow speed tape
recordings (VCR time-lapse recordings). The limiter circuit automatically keeps the STW1’s output at a relatively constant
level. This eliminates the need for the listener to reduce the volume control on the amplifier when sounds get louder.
Note: Do not use the STW1’s limiter circuit if you are using a tape recorder or other devices that use an AGC or
limiter circuit.
Recommended Jumper settings:
Stand-alone Application
Tape Recorder Application
Limiter “IN”
“OUT”
Treble Boost
“OUT”
“IN”
STW2 Base Station Controls
After connections have been made, apply power to the unit and the system is ready to use. You should hear STW1 audio
on the STW2 base station Speaker. Adjust the “Volume” knob to a comfortable level.
Sending a message to the STW1
Press and hold the “Push To Talk” button on the base station, and a green light will come on, indicating that audio is being
sent to the STW1. Speak in the direction of the Microphone, then release the button after you have finished your
message. The green light will go out. If necessary, you can adjust the Speaker volume by turning the “Remote Volume”
know clockwise for louder sound and counter clockwise for softer sound.
Recorder Switch
If the STW3 kit will be used with a recorder of some type, place the recorder switch in the “IN” position. In this position,
both live audio and playback audio can be heard through the STW2’s internal speaker. Connect the “Audio Out” jack to
the recording device’s “Audio In”, using the supplied RCA cables. Connect the “Audio In” jack to the recording device’s
“Audio Out.” In stand alone applications where there is no recorder or no need to playback recordings, place the recorder
switch in the “OUT” position. Note-both sides of conversations will be recorded.
Headphones
Plug headphones into the “Headphone” jack on the front panel of the STW2. Audio will be cut out on the STW2 Speaker.