Lectrosonics Inc SMWBC1 Manual De Usuario

21

Microphone RF Bypassing

When used on a wireless transmitter, the microphone 

element is in the proximity of the RF coming from the 

transmitter. The nature of electret microphones makes 

them sensitive to RF, which can cause problems with 

microphone/transmitter compatibility. If the electret 

microphone is not designed properly for use with wire-

less transmitters, it may be necessary to install a chip 

capacitor in the mic capsule or connector to block the 

RF from entering the electret capsule.
Some mics require RF protection to keep the radio sig-

nal from affecting the capsule, even though the trans-

mitter input circuitry is already RF bypassed.
If the mic is wired as directed, and you are having dif-

ficulty with squealing, high noise, or poor frequency 

response, RF is likely to be the cause.
The best RF protection is accomplished by installing RF 

bypass capacitors at the mic capsule. If this is not pos-

sible, or if you are still having problems, capacitors can 

be installed on the mic pins inside the TA5F connec-

tor housing. Refer to the diagram below for the correct 

locations of capacitors.
Use 330 pF capacitors. Capacitors are available from 

Lectrosonics. Please specify the part number for the 

desired lead style.

 

Leaded capacitors:  P/N 15117 

 

 

Leadless capacitors: P/N SCC330P

All Lectrosonics lavaliere mics are already bypassed 

and do not need any additional capacitors installed for 

proper operation.

CAPSULE 
 

CAPSULE 
 

SHIELD 
 

AUDIO 
 

SHIELD 
 

AUDIO 
 

BIAS 
 

TA5F 
 

CONNECTOR 
 

TA5F 
 

CONNECTOR 
 

Line Level Signals

The wiring for line level and instrument signals is:

•  Signal Hot to pin 5
•  Signal Gnd to pin 1
•  Pin 4 jumped to pin 1

This allows signal levels up to 3V RMS to be applied 

without limiting.

NOTE for line level inputs only (not instrument): 

If more headroom is needed, insert a 20 k resistor 

in series with pin 5. Put this resistor inside the 

TA5F connector to minimize noise pickup. The 

resistor will have little or no effect on the signal if 

the input is set for instrument.

Line Level 

Normal Wiring

Line Level

More Headroom

(20 dB)