Lectrosonics SMa User Manual download pdf (Page 14)

SMa Series

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

the 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

signal from affecting the capsule, even though the

transmitter input circuitry is already RF bypassed (see

schematic diagram).

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 connector

housing.

2 WIRE MIC 3 WIRE MIC

CAPSULE

SHIELD

AUDIO

SHIELD

AUDIO

BIAS

Alternate locations for bypass capacitors

TA5F

CONNECTOR

TA 5F

CONNECTOR

Preferred locations for bypass capacitors

Install the capacitors as follows: Use 330 pF capaci-

tors. 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.

Line Level Signals

The normal hookup for line level signals is: Signal Hot

to pin 5, Signal Gnd to pin 1 and pin 4 jumped to pin 1.

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

without limiting.

If more headroom is needed, insert a 20 k resistor in

series with pin 5. Put this resistor inside the TA5F con-

nector to minimize noise pickup.

LECTROSONICS, INC.

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 23 24

Comments to this Manuals

No comments

Lectrosonics SMa User Manual Page 14

Comments to this Manuals

Related products and manuals for Accessories communication Lectrosonics SMa