Owner's manual

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GENERAL TECHNICAL DESCRIPTION

UCR195 RECEIVER

The UCR195 is a high performance, dual-conversion,

UHF receiver. The RF performance is extremely stable

over a very wide temperature range, making the UCR195

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.

SIX-POLE HELICAL RESONATOR FRONT-END

The UCR195 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 UCR195 package.

This outstanding front-end keeps the UCR195 from

being affected by high power, adjacent RF signals and

also provides extremely high image rejection.

GaAs FET FRONT-END FILTER COUPLING

The UCR195 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 UCR195 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.

DIGITAL PULSE COUNTING DETECTOR

The UCR195 receiver uses an advanced digital pulse

counting detector to demodulate the FM signal, rather

than a conventional quadrature detector. The most

common problem with quadrature detectors is thermal

drift, particularly those that operate at higher frequencies

like 10.7 MHz. The UCR195 design presents an el-

egantly simple, yet highly effective solution to this age

old problem.

HELICAL

RESONATOR

GaAS

FET

470 - 608

MHz

XTAL

CONTROLLED

1ST

OSCILLATOR

8 POLE

LINEAR PHASE

FILTER

455KHZ

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

MONITOR

OUT

OUTPUT LEVEL ADJUST

AND

RANGE SWITCH

PILOT

TONE

MUTE

HELICAL

RESONATOR

AMP

DISABLE

PILOT

TONE

MOD

AUDIO

LED BARGRAPH METER

AMP

PILOT

LED

AMP

ENABLE

REVERSE

POLARITY

PROTECTION

+9V

REGULATOR

PWR

LED

PWR ON

AND

LO BATT LOGIC

TURN ON/OFF

DELAY

CH12 IN

BATTERIES

-8.8V

REGULATOR

INT

OFF

EXT

POWER

SWITCH

32kHZ

V+

MONITOR

LEVEL

METER

MODE

FIXED

Figure 1 - UCR195 Block Diagram