Lectrosonics M185 - Manual (Page 8)

M185 INPUT JACK WIRING
The wiring diagrams shown on the attached sheet represent the basic wiring necessary for the most common types
of microphones and other audio inputs. Some microphones may require extra jumpers or a slight variation on the
diagrams shown.
Caution - When wiring the connector, do not use the connector body for any electrical
connections. A common mistake is to use the connector body as an audio ground. The
connector body is already used as an RF ground and no other use is permitted.
It’s virtually impossible to keep completely up to date on changes that other manufacturers make to their products.
It is possible that you may encounter a microphone that differs from these instructions. If this occurs please call
our toll-free number listed in the back of this instruction manual. Our service department can answer your
questions regarding microphone compatibility.
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 wireless
transmitters, it will be necessary to install a chip capacitor in the mic capsule or connector to block the RF from
entering the electret capsule. These types of modifications are not shown on the attached instructions.
The M185 uses the shield of the microphone cord as the antenna. Other brands use a "dangling wire" to emit the
RF from the transmitter. There is really no difference between these two approaches, with respect to the effect of
the RF on the microphone capsule. Even in transmitters that utilize a "dangling wire," the microphone is still part
of the "ground plane" and is therefore still in the antenna circuit.
For answers to questions regarding microphone/transmitter compatibility, call our service manager or engineering
department at the factory.
5.1VDC 1K 1K
330
MPF480'S
7
22
K
.22M
+
1uH
3.3M
+
10K
1K
5
33M
510
+
4
6
2
3
4
3
2
1
60NH 5321
1N
-
+
330PF
330PF
Bias
22K
4
3
2
1
5
TO
LIMITER
CONTROL
TO
AUDIO
CIRCUITS
LECTROSONICS
M185
M185 Transmitter
Equivalent Input Circuit
1 - NEG GND (OR BIAS)
2 - POS BIAS (OR GND)
3 - MIC
4 - SOURCE LOAD
5 - LINE IN
Vcc
Figure 4 - M185 Input Connector and Schematic
PIN 1 Shield (ground) for positive biased electret lavalier microphones. Bias voltage source for negative biased
electret lavalier microphones. Shield (ground) for dynamic microphones and line inputs.
PIN 2 Shield (ground) for negative biased electret lavalier microphones. Bias voltage source for positive biased
electret lavalier microphones.
PIN 3 Low impedance microphone level input for dynamic microphones. Also accepts hand-held electret
microphones provided the microphone has its own built-in battery.
PIN 4 1K ohm source load for non-Lectrosonics electret microphones. Use in conjunction with other pins to
provide attenuation of high level input signals.
PIN 5 High impedance, line level input for tape decks, mixer outputs, musical instruments, etc.
7