Ericsson LBI-38505A Specifications download pdf (Page 7)

ALIGNMENT PROCEDURES

COMPLETE RECEIVER ALIGNMENT

EQUIPMENT REQUIRED

Test Set Models 4EX3A11, 4EX8K12, or 20,000 ohms-per Volt multimeter with a 1- Volt scale.

An 11.2 MHz signal source (Test Set Model 4EX9A10). Also a 406-512 MHz signal source with a one-inch piece of insulated wire no larger than .065

inch diameter connected to generator probe.

DVM.

Distortion Analyzer.

PRELIMINARY CHECKS AND ADJUSTMENTS

Connect the black plug from the Test Set to receiver metering jack J601, and the red plug to system board metering jack J905. Set the meter sensitivity

switch to the Test 1 (or 1- Volt position on the 4EX8K12).

For multi-frequency receivers with a frequency spacing up to 0.800 MHz for frequency range of 406-470 MHz, 0.900 MHz for frequency range of

470-494 MHz, or 0.750 MHz for frequency range of 494-512 MHz, align the receiver on the channel nearest center frequency.

For multi-frequency receivers with a frequency spacing exceeding the above but no greater than 1.60 MHz for frequency range of 406-470 MHz, 1.80

MHz for frequency range of 470-494 MHz, or 1.50 MHz for frequency range of 494-512 MHz, align the receiver using a center frequency tune-up ICOM.

These limits can be extended to 2.00 MHz, 2.30 MHz and 2.00 MHz respectively, with 3 dB degradation in standard receiver specifications.

With the Test Set in Position J, check for regulated +10 Volts. With multimeter, measure from J905-3 to J905-9.

If using multimeter, connect the negative lead to J601-9 (A-)

Disable the Channel Guard.

ALIGNMENT PROCEDURE

METERING POSITION

TEST INTERNAL MULTIMETER TUNING METER

STEP SET METERING -TO J601-9 CONTROL READING PROCEDURE

FM DETECTOR

1. A

(FM DET)

Pin 2 L603 0.38 Volt With no signal applied, adjust L603 for a meter reading of

approximately 0.38 Volt.

OSCILLATOR/MULTIPLIER

2. C

(MULT-1)

Pin 3 C406 Maximum Tune C406 for maximum meter reading.

3. C411, C416,

C306, C307

and C308

See

Procedure

Preset C411 and C416 to a position similar to C406. Next,

preset C306, C307 and C308 fully counterclockwise

(minimum capacity).

4. D

(MULT-2)

Pin 4 C411, C416,

C406

See

Procedure

Tune C411 and C416 for maximum meter reading. Next, retune

C406, C411 and C416 for maximum reading. Then carefully

tune C306 for a change in meter reading (peak or dip).

5. F

(MULT-3)

Pin 7 C306, C307

and C308

See

Procedure

Carefully tune C307 and C306 for maximum meter reading.

Repeat the procedure. Next carefully tune C308 for minimum

meter reading. Do

NOT readjust C307 and C308.

Cont’d.

METERING POSITION

TEST INTERNAL MULTIMETER TUNING METER

STEP SET METERING -AT J601-9 CONTROL READING PROCEDURE

RF AMP & SELECTIVITY

NOTE: IF AMP meter range is 0-700 mVDC with a high impedance DC voltmeter.

6. B

(IF AMP)

Pin 1 C305, C304

and A303-C2

Maximum Preset A303-C2 to mid position. Apply an on-frequency signal in

the hole adjacent to C304, keeping the signal below saturation.

Then tune C305, C304 and then A303-C2 for maximum meter

reading.

7. B

(IF AMP)

Pin 1 C304 and C303 Maximum Apply an on-frequency signal in the hole adjacent to C303,

keeping the signal below saturation. Then tune C304 and C303

for maximum meter reading.

8. B

(IF AMP)

Pin 1 C303 and C302 Maximum Apply an on-frequency signal in the hole adjacent to C302,

keeping the signal below saturation. Then tune C303 and then

C302 for maximum meter reading.

9. B

(IF AMP)

Pin 1 C301 thru C305,

A303-C2 (and

L2301 if present)

Maximum Apply an on-frequency signal to the antenna jack, keeping the

signal below saturation. Then tune C301 through C305 and A303-

C2 for maximum meter reading. In receivers with the UHS

preamplifier, also tune L2301 for maximum meter reading.

10. B

(IF AMP)

Pin 1 C301 thru C305,

A302-C2, C306,

C307 & C308

(L2301 if present)

Maximum Apply an on-frequency signal to the antenna jack and slightly tune

C301 through C305, A303-C2 (and L2301 if present) for best

quieting sensitivity. C306, C307 & C308 also may be tuned

slightly not to exceed 1/4 turn).

11. L603, R609 See

Procedure

Remove the Test set metering plug from J601. Apply a 1000

microvolt signal with 1 kHz modulation and 3 kHz deviation to the

antenna jack. Tune L603 for maximum voltage at 1.0 kHz and

adjust R609 for 1 Volt RMS measured with a DVM at P904-11

(VOL/SQ HI) and P904-17 (A-).

MIXER & IF

The mixer and IF circuits have been aligned at the factory and will normally require no further adjustment. If adjustment is necessary, use the procedure out-

lined in STEP 13.

12. L507, L503, L504 and C504,

T601, T602, and T603

Connect scope, signal generator, and probe as shown in Figure 6.

Set signal generator level for 3 to 5 µV and modulate with 20 Hz

at 12 kHz deviation. With probe between P904-4 (or J601-1) and

A-, tune L507, L503, L504, C504, T601, T602, and T603 for

double trace as shown on scope pattern. Preset T601-T603 to top

of coil form before tuning.

13. See

Procedure

Check to see that modulation acceptance bandswidth is greater

than ±7 kHz.

Refer to DATAFILE BULLETIN 1000-6 (IF Alignment of Two-Way Radio FM

Receivers) for helpful suggestions on how to determine when IF Alignment is required.

NOTE

406-512 MHz MASTR II RECEIVER

LBI-38505 LBI-38505

1 2 3 4 5 6 7 8 9 10 11 12

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Ericsson LBI-38505A Specifications Page 7

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