Lectrosonics R1a - Manual (Page 5)

IFB Receiver
Rio Rancho, NM 5
Figure 4 - R1a Block Diagram
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
Figure 3 - Frequency Adjustment
Figure 2 - Headphone cord strain relief
Headphone Jack (fig. 1 & fig. 2)
On the front panel is a 3.5mm mini phone jack to ac-
commodate a standard mono or stereo type 3.5 mm
plug. The unit will drive low or high impedance ear-
phones. The jack is also the receiver antenna input
with the earphone cord acting as the antenna. The
cord length is not critical but must be at least 6 inches
minimum.
Strain relief to avoid accidental disconnection can be
provided with the included small hook and loop strip.
Attach the adhesive strip side to the side of the receiver
with the opening end of the strip up - place the cord in
the strip and secure.
Mono Plug/Stereo Plug Usage
A Mono plug or a Stereo plug can be used with the
IFBR1a headphone jack directly. When a Mono plug is in-
serted, a special circuit senses the “ring” to “sleeve” short
and automatically switches off the ring to prevent excess
battery drain. To reset, switch power OFF then back ON.
Audio Level
Headphones and ear pieces vary widely in sensitiv-
ity and impedance making it impossible to design a
receiver with a fixed output power level that is correct
for all situations. High impedance phones (600 to 2000)
Ohms will have an inherently lower power level due
to their high impedance and likewise low impedance
phones may be extremely loud. CAUTION! Always set
the Audio Level knob to minimum (counter-clockwise)
when plugging phones into the jack, then adjust the
knob for a comfortable audio level.
Frequency Adjust (fig.3)
Two rotary switches adjust the center frequency of
the carrier. The 1.6M is a coarse adjustment and the
100K is the fine adjustment. Each transmitter is factory
aligned at the center of its operating range. The default
position of the frequency select switches is in the center
of the transmitter’s range. The receiver and transmitter
switches must be set to the same number/letter combi-
nation for proper operation.
To gain access to these switches, slide the access door
sideways with a fingernail.