Lectrosonics UCR195D - Manual (Page 6)

GENERAL TECHNICAL DESCRIPTION
UCR195 RECEIVER
The UCR195D is a high performance, dual-conversion,
UHF receiver. The RF performance is extremely stable
over a very wide temperature range, making the
UCR195D perfectly suited to the rough environmental
conditions found in the field. The proprietary audio
processing includes a dual-band compandor for very low
distortion and a superior signal to noise ratio. The
squelch system is operated by a separate pilot tone and
mutes the audio output directly at the output connector.
The audio output is calibrated for exact level matching,
with a ten LED bar graph meter.
DIVERSITY RECEPTION
The antenna phase switching diversity technique was
chosen in order to keep the receiver compact enough for
camera mounted or shoulder bag applications. This
diversity reception technique effectively minimizes
dropouts in short range situations where multi-path
reflections can cause serious problems. The optimum
diversity reception is realized with the diversity antenna
placed away from the receiver, however, dropouts are
significantly reduced with two antennas mounted directly
on the receiver.
SIX-POLE HELICAL RESONATOR FRONT-END
The UCR195D utilizes a six-pole helical resonator for
front-end filtering. The helical resonators are custom
manufactured in-house to provide the high performance
needed, yet still fit into the small UCR195D package.
This outstanding front-end keeps the UCR195D from
being affected by high power, adjacent RF signals and
also provides extremely high image rejection.
GaAs FET FRONT-END FILTER COUPLING
The UCR195D utilizes an ultra low noise GaAs FET
amplifier in the front-end section to compensate for the
required losses between filter stages. The GaAs FET
devices are extremely quiet, especially at the higher
frequencies in the UHF band.
DOUBLE BALANCED DIODE MIXERS
A double balanced diode mixer is used in the UCR195D
to produce the 10.7 MHz IF signal. The mixer produces
output at only the sum and difference signals, with
minimal spurious signals. This mixer offers a very high
overload threshold and a high degree of isolation be­
tween ports. This translates to the ability of the receiver
to accept higher input signals without overloading and
causing distortion and less cross talk between receivers
in multiple system installations.
10 POLE LINEAR PHASE FILTER
The 1st IF amplifier is a 4 stage amp with 2 poles of
filtering after each stage. The filters are high quality,
low distortion, constant group delay ceramic filters. This
special type of filter is needed to accommodate the wide
deviation of the 195 system. The 2nd IF incorporates 2
more poles of filtering.
HELICAL
RESONATOR
GaAS
FET
470 - 608
MHz
XTAL
CONTROLLED
1ST
OSCILLATOR
8 POLE
LINEAR PHASE
FILTER
455KHZ
BP
FILTER
10.7MHz IF
AMP
2ND MIXER
&
IF AMP
COUNTING
DETECTOR
32 kHZ
BLOCKING
FILTER
HI-LEVEL
DIODE MIXER
XTAL
CONTROLLED
2ND
OSCILLATOR
2:1
EXPANDER
TREBLE
2:1
EXPANDER
BASS
AUDIO
AMP
OUTPUT LEVEL ADJUST
AND
RANGE SWITCH
XLR
OUT
PILOT
TONE
MUTE
HELICAL
RESONATOR
AMP
DISABLE
PILOT
TONE
MOD AUDIO
LED BARGRAPH METER
AMP
PILOT
LED ENABLE
REVERSE
POLARITY
PROTECTION
+9V
REGULATOR
PWR
LED
PWR ON
AND
LO BATT LOGIC
TURN ON/OFF
DELAY
CH12 IN
9V
BATTERIES
-8.8V
REGULATOR
V CC
V EE
INT
OFF
EXT
POWER
SWITCH
32kHZ
V+
3
2
1
METER
MODE
LO
HI
FIXED
HI
FIXED
LO
ANTENNA
SWITCHING
Figure 1 - UCR195D Block Diagram
6