Lectrosonics MM400 - Manual - Manual (Page 9)

Frequency Agile UHF Miniature Belt-Pack Transmitter
ADJUSTING THE TRANSMITTER FREQUENCY
If you are experiencing interference from another signal on your frequency,
you may want to change the operating frequency of your system. The left
switch changes the operating frequency by 1.6 MHz per step and the right
switch changes it 100 kHz per step. If you are experiencing interference,
change the operating frequency in 100 kHz steps to find a clear channel. If it
is not possible to find a clear channel using the 100 kHz switch, return it to
its original position and change the 1.6 MHz switch by one click then try the
1.6M 100K
100 kHz switch again. Some Lectrosonics receivers have a built-in frequency
scanner which makes finding a clear channel very easy. See the separate receiver manual for instructions.
0 1
2
3
4
5
6
7 8
9
A
B
C
D
E
F 0 1
2
3
4
5
6
7 8
9
A
B
C
D
E
F
To gain access to these switches, unscrew the retaining bolt that holds the access door to the case. It is not neces­
sary to remove the bolt from the case since it is retained by the case with enough room to still remove the access
door. Pull the access door away from the case and swing the door to the side to gain access to the frequency
switches.
MICROPHONE RF BYPASSING
Some mics require RF protection to keep the radio signal
All Lectrosonics lavalier mics are already bypassed and
from affecting the capsule, even though the transmitter
do not need any additional capacitors installed for proper
input circuitry is already RF bypassed.
operation.
If the mic is wired as directed, and you are having diffi­
culty with squealing, high noise, or poor frequency
2 WIRE MIC 3 WIRE MIC
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
possible, or if you are still having problems, capacitors
can be installed on the mic wires inside the TA5F connec­
tor housing.
Install the capacitors as follows: 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
INPUT JACK WIRING
2k
6V Mic Bias
30uF
2k
FB 100 2k
To Mic Amp
2.2nF
330pF 330pF
Mic
Jack FB
CAPSULE
CAPSULE
SHIELD
AUDIO
SHIELD
AUDIO
BIAS
MIC
CONNECTOR
MIC
CONNECTOR
Preferred locations for bypass capacitors
Alternate locations for bypass capacitors
Rio Rancho, NM – USA 9