Ericsson LBI-38505A manual Alignment Procedures, Complete Receiver Alignment

LBI-38505 ALIGNMENT PROCEDURES LBI-38505

COMPLETE RECEIVER ALIGNMENT

EQUIPMENT REQUIRED

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

2.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.

3.DVM.

4.Distortion Analyzer.

PRELIMINARY CHECKS AND ADJUSTMENTS

1.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.

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

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

5.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	1	Pin 2	L603	0.38 Volt	With no signal applied, adjust L603 for a meter reading of
	(FM DET)	(FM DET)				approximately 0.38 Volt.
				OSCILLATOR/MULTIPLIER
2.	C	3	Pin 3	C406	Maximum	Tune C406 for maximum meter reading.
	(MULT-1)	(MULT-1)
3.				C411, C416,	See	Preset C411 and C416 to a position similar to C406. Next,
				C306, C307	Procedure	preset C306, C307 and C308 fully counterclockwise
				and C308		(minimum capacity).
4.	D	4	Pin 4	C411, C416,	See	Tune C411 and C416 for maximum meter reading. Next, retune
	(MULT-2)	(MULT-2)		C406	Procedure	C406, C411 and C416 for maximum reading. Then carefully
						tune C306 for a change in meter reading (peak or dip).
5.	F	5	Pin 7	C306, C307	See	Carefully tune C307 and C306 for maximum meter reading.
	(MULT-3)	(MULT-3)		and C308	Procedure	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	2	Pin 1	C305, C304	Maximum	Preset A303-C2 to mid position. Apply an on-frequency signal in
	(IF AMP)	(IF AMP)		and A303-C2		the hole adjacent to C304, keeping the signal below saturation.
						Then tune C305, C304 and then A303-C2 for maximum meter
						reading.
7.	B	2	Pin 1	C304 and C303	Maximum	Apply an on-frequency signal in the hole adjacent to C303,
	(IF AMP)	(IF AMP)				keeping the signal below saturation. Then tune C304 and C303
						for maximum meter reading.
8.	B	2	Pin 1	C303 and C302	Maximum	Apply an on-frequency signal in the hole adjacent to C302,
	(IF AMP)	(IF AMP)				keeping the signal below saturation. Then tune C303 and then
						C302 for maximum meter reading.
9.	B	2	Pin 1	C301 thru C305,	Maximum	Apply an on-frequency signal to the antenna jack, keeping the
	(IF AMP)	(IF AMP)		A303-C2 (and		signal below saturation. Then tune C301 through C305 and A303-
				L2301 if present)		C2 for maximum meter reading. In receivers with the UHS
						preamplifier, also tune L2301 for maximum meter reading.
10.	B	2	Pin 1	C301 thru C305,	Maximum	Apply an on-frequency signal to the antenna jack and slightly tune
	(IF AMP)	(IF AMP)		A302-C2, C306,		C301 through C305, A303-C2 (and L2301 if present) for best
				C307 & C308		quieting sensitivity. C306, C307 & C308 also may be tuned
				(L2301 if present)		slightly not to exceed 1/4 turn).
11.				L603, R609	See	Remove the Test set metering plug from J601. Apply a 1000
					Procedure	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.

NOTE

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.

12.	L507, L503, L504 and C504,		Connect scope, signal generator, and probe as shown in Figure 6.
	T601, T602, and T603		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	Check to see that modulation acceptance bandswidth is greater
		Procedure	than ±7 kHz.

406-512 MHz MASTR II RECEIVER

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