Motorola T1959A_T1961A_T1962A User guide

@ MOTOROLA INC.

MOTOROLA HF.SSB

Communications

Group

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Automatic Antenna Tuner

Models T1961Aand T1962A

Installation Procedure

1. INTRODUCTION
(RefertoFigure 1.)

1.1 Motorola HF-SSB Automatic Antenna Tuners,

Models T1961A and TI962A, are antenna match-

ing networks rated at 125 watts peak-envelope-power
(PEP). Model T1961A Antenna Tuner matches the im-

pedance of an end-fed antenna (vertical whip or random
length wire) into a nominal 50-ohm impedance source
with a frequency range from 2-to-18 MHz. Model
T1962A Antenna Tuner performs the same impedance
match, but it can be used only with a 23' whip antenna
and at a frequency range from 2-to-9 MHz.

1.2 AutomatiC tuning is accomplished through

microprocessor control of reed relays that switch
inductors and capacitors in and out of the matching net-
work. The balance of this installation procedure
describes preinstallation instructions, installation in-
structions and ground systems for the radio and the

antenna tuner.

.2. PREINSTALLA TION INSTRUCTIONS

2.1 TUNE POWER ADJUSTMENT

....

, "7 CAUTION

The following adjustments to the
TRITON 20 or TRITON 12 and 24 chan-

nel radios must be performed before mak-
ing electrical connections to the antenna
tuner.

2.1.1 TRITON 20 Adjustment

Step 1. In the TRITON 20 instruction manual
(68P81044E20), refer to the TRN4038A Power

Amplifier circuit board overlay and schematic.
Step 2. With the radio in the TUNE MODE, adjust

potentiometer R441 for 3 watts :t 1 watt of power out-
put into a 50-ohm resistive load.'

FAEPS-3000S-0
"5381

Figure 1. AutomaticAntenna Tuner

@ Motorola, Inc. 1979

All Rights Reserved
Printed in U.S.A.

2.1.2 TRITON 12 and 24 Channel Adjustment

Step 1. In the TRITON 12 and 24 channel radio in-
struction manuals (68P81O30E35 and 68P81O34EO5),
refer to the TLN1752A Power Amplifier circuit board
overlay and schematic diagram.

Step 2. With the radio in the TUNE MODE, adjust
potentiometer R41 for 3 watts :t 1watt of power output

into a 50-ohm resistive load.

It@@jfn(fi)fi@@11Wff fiU:Ji(fi)~g@{f\VJfi~

1301 E.Algonquin Road, Schaumburg, II.60196

68P81110E64-0

5/15/SD-PHI

2.2

RADIO MODIFICATIONS

2.2.1 The TRITON 20 and TRITON 12 and 24 chan-

nel radios require circuitry modification if (hey

were built before July 1, 1980. Those radios built after
this date do not require the following modifications. All
the components required for these modifications are in

a small package of parts supplied with the antenna
tuner. Since components for both radios are included,
some components are not used, depending upon which

radio is modified.

2.2.2 TRITON 20 Modifications
(Refer to Table 1, and Figures 2 and 3.)

The TRITON 20 modification consists of the ad-

dition of 2 components to a circuit board.

Step 1. In the TRITON 20 instruction manual, locate
the TRN4032A "A" circuit board overlay and

schematic diagram.
Step 2. Select the components listed in Table 1, and

install the diode and resistor as illustrated in Figure 2.

Table 1. TRITON 20 M odijication Parts List

""8

100

8.0V

CR110

J3-1O

9T

CR21

PADISABLE

CR12

TD ROt

Figure3.

TRITON 20SchematicDiagramModijications

2.2.3

tions consist of changes made on two separate circuit
boards. The first modification is done to the main cir-

cuit board by addition of components listed in Table 2.
Figures 4 anCb.Sillustrate where these components are in-

stalled. The- second modification is done to the
transmit/receive switch circuit board by the addition of
components listed in Table 2. Figures 6 and 7 illustrate

where these components are installed.

TRITON 12 and 24 Channel Radio

Modifications

(Refer to Table 2 and to Figures 4 thru 7.)
The TRITON 12 and 24 channel radio modifica-

CA19

A198

CA110

CA12

CAUTION

Early versions of 12 and 24 channel

TRITON radios must have resistor R44

on TLN17S2A Power Amplifier changed

to a 3.3k ohm, SOJo,1/4 watt resistor for

proper antenna tuner operation.

Step 1. In the TRITON 12 and 24 channel radio in-
struction manuals, locate the TUAlllOA or TUA1120A
Universal Radio Chassis and Main Board "M" overlay

and schematic diagram.

Step 2. Select the components (CRSI9 thru CR523
and RSI8) listed in Table 2, and install the diodes and
resistor as illustrated in Figure 4. Use sleeving on the
component leads.

Table 2. TRITON 12 and 24 Channel Radio

a16

""'-30007-0
IC><OI

Modijication Parts List

Figure2.

TRITON 20CircuitBoardModifications

2

J

09 as

RIS R24 CR9

CR4

P/O
TRN6227A
TRN6429A
TRN6430A

.- ..'0"" .

""'-30011-0
..r.<o,

'.J

I .

v

P/O TRNS229A

TRNS867A
TRNS66SA

RSla

F :JOCOO-O
'.SAOI

Figure4.

TRITON 12and 24 ChannelMain CircuitBoard

Modifications

CATHODE OF CR41' «RANGE 11

CATHODE OF CR41T ,(RAHGE Z)

PIO IIAHOSWITCHIHG

CIRCUITRY SECTION ON

AWN BOORD"" CATIiOOE OF Cll419 «(RANGE 41

CATHOOE OF C114t. ((RANGE 31

1

CATItODE OF C114ZO ,(lUNGE 5)

CATHOD£ OF VR42S .d!'OD':5AOLE)

G£PS-3000.-o

Figure 5.

TRITON 12 and 24 Channel Main Circuit Board

Schematic Diagram Modifications

Step 3. In the instruction manual, locate the
TRN6227A; TRN6429A, or TRN6430A Transmit!
Receive Switch circuit board overlay and schematic

diagram.

Step 4. Remove resistor R24 (220 ohm) from the cir-
cuit board and lay it aside. It will not be used.

Step 5. Select the components (CR9 and R24) listed in
Table 2, and install the diode and resistor as illustrated

in Figure 6.

CRS19

"""20

"""21

CIISn

""SD

1tS1.

-

100

TRITON 12and24 ChannelSmall CircuitBoard

Figure6.

Modifications

024

.) (PO.DI:5A8LE1 ""9

11

-;;0

BEPS->OOIO-O

Figure 7.

TRITON 12 and 24 Channel Small Circuit Board

Schematic Diagram Modifications

(PO<'_BlT'(T

Q9

M9642

CRT

3. INSTALLATION INSTRUCTIONS

GENERAL

3.1

The procedure for a good installation is essentially

the same for either the Model Tl961A or Model T1962A

Antenna Tuner. If the Model T1961A Antenna Tuner is
employed, antennas of the end-fed variety of a 23-foot

whip or up to a 6O-foot long wire may be used with a
frequency range from 2 to 18 MHz. If the Model
T1962A Antenna Tuner is employed, its use islimited to
a 23-foot whip antenna with a frequency range from 2

to 9 MHz. The antenna should be installed as close as
possible or within a maximum of 3 feet of the tuner. The
ground system should be as close as possible or within a

maximum of 5 feet of the tuner.

3

3.2 LOCATION
(Refer to Figure8.)

Selection of a location for the antenna tuner

should be such that it is as close to the antenna as possi-
ble. Long "lead-in" wires greatly increase the possibili-
ty of creating radio frequency interference (RFI) with
other electronic equipment on the vessel. There are two
factory installed angle brackets attached to the bottom

of the antenna tuner for mounting purposes. Several
holes and slots are provided on each bracket. It is not
necessary to remove the brackets to mount the tuner.

CAUTION

Regardless of antenna tuner mounting
position, the selected drain hole must face

downward.

NOTE

The dealer or installer must supply the
necessary stainless steel mounting hard-

ware.

GAEPS-30012-D

ANTENNA

TUNER

7

?

GAEPS-30013-0

Figure 9. Mounting Positions

3.4 GROUNDING

A good ground system is required for efficient
antenna tuner operation. Use the ground lug on the
antenna tuner for ground strap attachment. Ground
returns for the electrical circuits may be provided
through the deck or hull of the vessel if these are
metallic; otherwise, a copper strap four inches wide

should be installed from bow to stern. For more detailed
information regarding grounding, refer to. the

GROUND SYSTEMS section of this manual.

DRAIN SCREWS

Figure 8. Antenna Tuner Housing

3.3

DRAIN SCREW REMOVAL
(Refer to Figure 9.)

The antenna tuner has provisions for selection of

one of two drain screws for removal of condensation.
One screw is positioned on the bottom of the housing,

and the other is on the end of the housing. Proper orien-
tation of the drain hole is essential for normal tuner

operation. Remove and discard one screw from the sur-
face that will be at the lowest position when the tuner is

mounted.

4

WARNING

Do not install the antenna tuner without
an adequate ground system.

3.5 CONTROL CABLE ASSEMBLY AND

INSTALLATION

The control cable must be field assembled. Table 3

lists the items required for assembly of the cable. Of
those parts listed, the connector kit and solder lugs are
supplied with the antenna tuner, but the 3-conductor
cable must be supplied by the dealer or the installer. The
following steps outline the control cable assembly and
installation procedure.

--

(;

Table 3. Control Cable Parts List

.For a detailed parts breakdown of the TRN4423A Connector Kit,

see PEPS-30lOS. at the rear of this manual.

MAIN
BRACKET

CABLE
RETAINER

I ',~

Step 1. Assemble the control cable as illustrated in
Figure 10and asdirected inFigure 11.

Step 2. Insert the completed I5-pin plug into the
antenna tuner connector of the TRITON radio.

Step 3. Route the other end (solder lugs) of the control
cable through the vessel to the antenna tuner.

3-GONDUCTOR
CONTROL
CABLE

WIRE

EYELET

IS-PIN CONNECTOR

()

I-~/I

(31

SOLDER LUGS

STEP 1:
STRIP INSULATION
11<SOLDER LUG
TO EACH CONTROL
WIRE.

~

~

STEP B:
PULL CONTROL CABLE

BACK INTO MAIN
BRACKET SOTIE-WRAP
IS FLUSH WITH

BRACKET OPENING.
ATTACH STRAIN RELIEF
OVER TIE-WRAP AND
SNAP CABLE 11<STRAIN

RELIEF INTO BRACKET.

,. -J .LREW

~

STEP 2:
FEED CONTROL
CABLE THROUGH
HOLE IN MAIN
BRACKET.

, '

P

STEP 9:
LOCK SIDE BRACKETS TO
CONNECTOR TABS

AND INSERT SCREWS SECURING SIDE
BRACKETS TO MAIN BRACKET.

'~~

10F'

1 OF 3 CONNECTIONS SHOWN

Figure 10. Control Cable Assembly

STEP 3:
STRJP In" OFF
OUTER JACKET.
STRIP INSULATION
BACK II'" ON EACH WIRE.

STEP 7:
ATTACHTJE-WRAP 1/B'" FROM
OUTER JACKET EDGE.

STEP .:
ATTACH EACH
CONTROL WIRIOTO
CHOKE-PIN ASSEMBLY

THROUGH AN EYELET

AND SOLDER.

STEP S:
SLI DE HEAT
SHRINKABLE TUBING
OVER ASSEMBLY
11<SHRINK.

---

~

Q

CONNECTOR
MATING
SERRATIONS

DOWN

GBEPS-30047-0

~;::~EACH

CONTROL WIRE WITH
CHOKE-PIN ASSEMBLY
INTO ANTENNA TUNE
CONNECTOR. REFER TO
FIGURE. FOR CORRECT
CONNECTIONS.

GBEPS-30070-0

,;

Figure 11. Control Cable Assembly Procedure

5

,.

4. GROUND SYSTEMS

(Refer to Figures 14and 15.)

R.F.

COAX

MOUNTING~
SCREW

Electrical and Mechanical Connections

Step 4. Route and connect the solder lugs of the con-
trol cable as shown in Figure 12. Tie-wrap the control
cable to the coaxial cable, and attach the lug housing
with mounting screw.

3.6 COAXIAL CABLE
(Refer to Figure 13.)

Use type RG-58/U or RG-8/U, 50-ohm, coaxial .

cable with the appropriate UHF connectors (PL-259) on
both ends to interface the RF OUTPUT from the radio
to the RF INPUT to the antenna tuner.

C~J':""

TRITON HF-SS8

RADIO

Figure12.

3 CONOUC1aI CASU:

CONtRO<. CIN€

~/

,13(') ANTT1JNE I

ro!MlNAl.S \

~

,w...

He

.rl Tl961AOR

_F

INPUT

\ ~ ORRGlIV COAX

BEPS-3OO1'-0

Figure 13. Electrical Block Diagram

-~

GAEPS-30071-O

'-AHTEHNA

TlKZA

ANTENNA

T\JNER

'--GOlD WG

GOlD STRAP

4.1 A common ground for the entire radio system
(radio, dc power supply, antenna tuner, etc.) is re-

quired for proper system performance. This type of
grounding is accomplished through the use of three inch
wide grounding straps terminating at the GROUND
LUG on the antenna tuner, which in turn is connected

to the antenna ground plane. When at all possible,
avoid multiple path ground connections. They result in
ground loops which may have high circulating currents.
On certain operating frequencies, ground loops cause
radio and/ or antenna tuner instability.

4.2 The ground strap to the antenna tuner must be

within a maximum of 5 feet of the tuner. If the

ground strap is long in terms of the operating frequency
wavelen'6th, it can actually present a high impedance to
the ground lug on the antenna tuner. As a result, the
antenna tuner is electrically "floating" above the
reference ground of the system.

4.3 An adequate system ground is usually easily ob-

tained on a metal hulled ship with a metal deck.

All communications equipment can be grounded to the

,metal structure of the ship at convenient places.

4.4 Wood and fiberglass vessels present more difficult

. grounding problems. Large ground straps are re-

quired to electrically bond equipment together, and an
artificial ground plane must be created. Either of two
methods is used to achieve the required ground plane:
ground plates or screening. Ground plates or screening
is installed inside the hull of the craft so that good elec-
trical contact with the' water is made through the
capacitive effect of the hull (dielectric). At least 100
square feet of the area below the water line is recom-
mended. Figure 14 shows an example of a ground
system where a ground plate is placed on the inside of

the hull of the vessel.

4.5 An artificial ground plane can be further improved
with the addition of copper screening connected

through a ground strap to the base of the antenna tuner
and placed in the immediate vicinity of the antenna
tuner. The antenna tuner should also be grounded to
copper pipes, the metal water tank, and the engine to ex-
tend the ground system. The addition of 1/4 wavelength
radials extending from the ground lug of the antenna
tuner creates a further improvement in system per-
formance. Figure 15shows a radial ground system.

.

.

J !

.

6

.

ANTENNA

~

COPl'ER
SCREEN

ANTENNA TUNER

"

METAL
WATER

\)

TANK

~}

GROUND PLATE

7

'7

Figure 14.

Ground System on Fiberglass Vessel

BULKHEAD

FEED- THRU
INSULATOR

GBEPS-30016--D

1/4 WAVE RADIALS AT
FREQUENCIES OF OPERATION

Figure 15. Radial Ground System

~~"'-l

LEAD-IN WIRE

GAEPS-30017 -0

7

. . '!. ~ j ~' "

J~ A=c== : - - a ~m - ft

2

1;00--1---~--' i , 1

<-4 12

~' L 7

I f

5 5 3

GBEPS-:JO103-0

Figure 16. Control Cable Parts Detail

;?

CODE

1
2
3
4
5
6
7
8
9

10
11
12
13
14
15

I

MOTOROLA

PART NO.

29-83883C08
42-82018H02
7-82232L01
7-82233L01
3-115613
4-135651

42.10217A02

5.820SOH04

24-83397L01

37.132049
29-841SOL02
14-82834H02

42.10283A20
14-844951.101

3.139102

LUG, solder; 3 used

STRAIN RELIEF
BRACKET, side; 2 used

BRACKET, main

SCREW,machine; 4-40x 1/4";4 used

LOCKWASHER, /Ij)split; 4 used

TIE.WRAP; 2 used
EYELET; 3 used
CHOKE, RF, 30uH; 3 used
TUBING, clear 1/4"; 3 used
TERMINAL, plug; 3 used
INSULATOR, plug; 15 pin

CLIP, cable
INSULATOR

SCREW, tapping; 8-18 x 1/2"

parts I$t

TRN4423A Connector Kit

......

"--\ ~~J.

15~"QJ

GAEPS-30104-Q

Q

PL.6953-O

DESCRIPTlON

Figure 17. Housing Parts Detail

TRN4423A Connector Kit
Parts List
Motorola No. PEPS-30105-0

51151SG-PHI

@ MOTOROLA INC.

Communications

/'~

$

1.

1.1 Motorola HF-SSB automatic antenna tuners are

peak-envelope-power. Selection of the network com-
ponents for antenna matching is performed by a

microprocessor-based circuit that monitors antenna
conditions each time a channel is changed. The entire
tuning process usually takes less than one second.

Microprocessor control eliminates the need for pro-
gramming, preset adjustments, manual tuning, or
manual adjustments during installation or operation.

1.2 The automatic antenna tuner can accommodate

nels can be added at any time without adjusting the

) tuner.

\ .. : 1.3 The automatic antenna tuner includes stainless

that insure corrosion resistance and durability. Installa-
tion is simplified; the automatic tuning capability
eliminates the need to open the tuner housing during in-

stallation.

1.4 Models TI959A and TI961A match the impedance

23-60 foot random length wire) into a nominal 50-ohm

Group

DESCRIPTION

antenna matching networks rated at 125 watts

any number of channels automatically. .Newchan-

steel hardware and a weather resistant housing

of an end-fed antenna (23-35 foot vertical whip or

AUTOMATIC ANTENNA TUNER

MOTOROLA HF-SSB

MODELS T1959A, T1961A, T1962A

impedance source with a frequency range from
2-18 MHz. Model T1961A includes the TRN4423A con-

nector kit for field assembly of the necessary control
cables. Model T1959A uses factory assembled accessory

cables, TKN8123A, TKN8120A and TKN812IA. Other-
wise, the T1959A and TI961A are identical. T1959A
and TI961A Antenna Tuners are compatible with the

102-inch niobile whip antenna (TAAI OOOA) from
2-18 MHz if a TKN8119A antenna matching harness is

used.

Model T1962A Antenna Tuner is capable of
matching a 23-foot whip antenna from 2-9 MHz. This
model also includes the field assembled TRN4423A con-

nector kit.

NOTE

Older versions of Motorola single side-
band radios must be modified before they

can be used with these tuners. Please refer
to the installation manual for the specific

tuner for more details. Installation
manual 68P81111EI6 applies for tuner

Model T1959A. Installation manual
68P8111OE64 applies for Models T1961A

and T1962A.

2.

MODEL COMPLEMENTS

FAEPS-3000S-0
"5381

)

--~

@ Motorola, Inc. 1981

All Rights Reserved

Printed in U.S.A.

Figure 1.Automatic Antenna Tuner

~h1(f1)fi@@IIlY!JJ(fnltJi(fl)~ff@ff\VIfi~

1301 E.Algonquin Road, Schaumburg, II.60196

T1959A 2-18 MHz Base Tuner consists of:

.TLAl1O2A

.THN6410A

.TLA6102A

T1961A 2-18 MHz Tuner consists of;

.TRN4423A Connector

.TLA II 02A Tuner

.THN641OA Housing

. TLA61O2ARFBoard

T1962A2-9MHz Tuner consistsof;

. TRN4423A Connector

. TLA1112ATuner

.THN64lOA Housing

.TLA6112A RF Board

68P81045E90-A

10/1/81. NWP

3.

PRE-OPERATIONAL CHECK

3.1 The antenna tuner is thoroughly checked and in-
spected at the factory. However, if the tuner is to

be installed in a remote location or stocked on a shelf
for several months, a pre-operational check on a service

bench is recommended.

3.2

The recommended set-up for the pre-operational
check consists of all the components that comprise

the radio system (with the antenna being replaced by an
antenna simulator circuit). The recommended set-up is

shown in Figure 2.

NOTE

A TKN8119A Mobile Antenna Matching
Harness must be used when checking a
mobile whip antenna. Figure 3 shows a
recommended set-up.

TUNER

Figure 2. Typical Pre-Operational Check Configuration

TUNER GROUND

TERMINAL

MOUNTING RAIL

MOUNTING SURFACE

7

EYELEl

GAEPS-31085-0 j

,;,

I

I

Figure 3. TKN8119A Mobile Antenna Matching Harness

2

A

3.3 Circuits for construction of the antenna simulator
are shown in Figures 4 through 6.

-"

~

}

Figures 4 and 5 apply only for 23 to 60
foot antennas, whip or long wire.

NOTE

mode) of 3 :t 1 watts into a 50-ohm load. Refer to the
radio instruction manual for the procedure for ad-

justing the radio power level in the tune mode.

3.6 Check the tuner operation by following the pro-
cedure given below.

Step 1. Set up the components of the radio installation
as shown in Figure 2.

-.-7/

l ..

900 UHOHMS

P

= .EPS' 3'000-0

Figure 4. Antenna Simulator Circuit for Models

TI959A, T1961A, T1962A (2-10.8 MHz)

1

ssp,

2 OHMS

OP' 3.'UH ,.

'EPS.31038.0

Figure 5. Antenna Simulator Circuitfor Models

-"\

"1

T1959A and T1961A (10.8-18 MHz)

1

32.'

2 OHMS

0.5U'

100 OHMS

Siep 2. Select Channell and turn the radio on. During

the initial 1 to 2 seconds, the wattmeter should indicate

a power level of approximately 3 watts. The radio
should then return to the receive mode.

CAUTION

Step 3 should only be performed with an
antenna simulator rated for full transmit

power or with a properly installed anten-
na. "':r

Step 3. Whistle into the microphone. Check the watt-
meter for forward and reverse power levels. The for-

ward power level should be more than three times the
reverse power level. .

Step 4. Repeat Steps 2 and 3 for each of the other
radio. channels. Insure that the .proper antenna

simulator is used for each channel frequency. .

MAINTENANCE

4.

4.1

RECOMMENDED TEST EQUIPMENT
The test equipment listed in Table I is recommend-

ed for maintaining and troubleshooting the automatic
antenna tuner.

~

AE.5-3103&-.

Figure 6. Mobile Whip Antenna Simulator Circuit

, 3.4 Select and construct the antenna simulator circuit

that corresponds to the antenna tuner model being

checked and the operating range of the radio.

CAUTION
These antenna simulator circuits are only
recommended for system tests in the tune-

up mode. Tests in other modes should on-
ly be made if the simulator circuits are
constructed with parts that are rated to
handle maximum transmitter power.

'\

-_J 3.5 To insureproper operation of the tuner, the radio
must be adjusted for a power level (in the tune

A

Table 1. Recommended Test Equipment

PREVENTIVE MAINTENANCE

4.2

4.2.1 Check all external surfaces of the equipment to
see that they are clean. Inspect all connecting

cables and wires for damage or loose connections. It is
especially important that the ground and antenna wires
make good connections at the tuner. Carefully check the
antenna and verify that it is properly insulated from any
metal objects. .

3

4.2.2 If the equipment surfaces are dirty, wash the ex-

fixed output capacitance of 50 picofarads.

ternal surfaces with mild soap and water using a

clean cloth. Be careful not to allow the electronic com-
ponents or connectors to get wet.

5.3.1.2 There are five steps of switchable input
capacitance arranged in a binary order, that is,..

the value of a switchable capacitance is half the value of

4.2.3 Preventive maintenance should be scheduled
regularly, i.e. monthly, quarterly, annually. The

interval of maintenance depends on equipment usage
and environment.

the next largest switchable capacitance. The values of
switchable input capacitance are 2000, 1000, 500, 250,
and 120 picofarads. The values of switchable output
capacitance for Models T1961A and T1959A are 400,

200, 100, 50, and 27 picofarads. The values of switch-

4.3 TROUBLESHOOTING

able output capacitance for Model TI962A are 50 and
100picofarads.

Check for proper operation of the tuner by per-

forming the procedure listed under the Pre-Operational
Check paragraph of this manual. If the tuner is not
operating properly, use the notes on the schematic
diagram and the attached troubleshooting chart to
localize the defective component.

5.3.1.3 There are ten steps of switchable inductance
arranged in binary order. The values of switch-

able inductance are: .08, .15, .29, .55, 1.05, 1.99, 3.8,

7.24, 13.78, and 26.25 microhenries.

5.3.2 Phase Detector

5.

THEORY OF OPERATION

-y
The phase detector circuit consists primarily of

5.1 CIRCUIT FUNCTION

TI, Ul, U2, U3, and U6D. This circuit compares the
phase of the rf voltage to the phase of the rf current and

A fixed length antenna presents greatly varying
impedances when operating over a wide frequency
range. The tuner must enable the ant.enna to resonate by
compensating for the capacitive or inductive reactance
present. It must also match the resistive component of
the antenna to present a 50-ohm load to the radio out-
put. This antenna tuner is designed to perform both of
these functions automatically in less than 2.5 seconds
without making any preliminary adjustments or set-

generates either a logic high or logic low at U6-14. When
the antenna and the tuner represent an inductive load to
the rf output of the radio, the rf current lags the rf
voltage, resulting in a logic high (5 V) at U6-14. When
the antenna and tuner represent a capacitive load to the
rf output of the radio, the rf current leads the rf voltage,
resulting in a logic low (0 V) at U6-14.

5.3.3 VSWR Detector

tings.

The VSWR detector consists primarily of T2 and

5.2 CIRCUIT CONFIGURATIONS

U6C. A voltage proportional to the forward power of
the transmitter output is developed at U6-1O. A voltage

Two different circuit configurations are used to
tune the antenna. To match antennas with capacitve
reactance, a pi configuration is used. The pi configura-
tion consists of parallel capacitance, followed by series
inductance, followed by parallel capacitance. To match
antennas with inductive reactance, an L configuration is

"

used. The L configuration consists of series inductance
followed by parallel capacitance.

proportional to the reverse power of the transmitter out-
put is developed at U6-11. If both U5B and U5C are not
activated by the microcomputer, U6-13 drops from
5 volts to 0 volts when a VSWR of 4:1 is achieved. If

U5B is activated, the 5 to 0 volt transition takes place

when a VSWR of 2:1 is acheived. If U5C is activated,

the 5 to 0 volt transition takes place when a VSWR of

1.5:1 is acheived.

5.3

CIRCUIT DESCRIPTIONS

5.3.1

Tuning Elements

5.3.4 Channel Change Circuit

The channel change circuit consists primarily of

transistors Q28-Q33 and inverter U7C. When a radio

5.3.1.1 The tuning elements of the antenna tuner con-
sist of inductive and capacitive components

that are switched into the rf circuit by a series of reed
relays. The tuning elements are selected by the tuner
microcomputer, which enables the transistor driver cir-
cuits that activate the relays. The tuning element net-
work consists of parallel capacitance, followed by series
inductance, followed by parallel capacitance. In addi-
tion, there is an output inductance of 26.25 micro-
henries that can be selected by the microcomputer and a

4

.J

channel change takes place, the channel change circuit
applies a negative going, 0.5 second pulse to the
POWER ACK and TUNED INPUT ports of the micro-
computer. This pulse prohibits the microcomputer from
beginning a tuning sequence until radio channel selec-

tion is complete. One-half second after the channel

change is complete, there is a transition from 5 volts to
0 volts at U7-6. The transition enables the microcom-~.

puter to begin its tuning' sequence. The channel change'
circuit responds only to channel selections made with

A

the channel selection knob. If channel change is in-
itiated by the A/B button, the tune line circuit is used to

<'1 initiate the tuning sequence. Refer to the paragraph that

.' } describesthe tune linecircuit.

5.3.5

Tune Power Detector

The tune power detector consists of U5A, U6A,
and U6B. A voltage proportional to the forward power
from the transmitter output is applied to U6-5. When
the forward power level is between 1and 6 watts, U5A is
activated and a logic low is applied to the POWER ACK
port of the microcomputer to verify that the proper

...

power level for tuning is present.

5.3.6 Tune Line Circuit

5.3.6.1 The tune line circuit consists of U5F, U5G,
U7E, U7F, and a portion of U9. During a tun-

ing sequence, U8-33 applies a low to U7-14. The high at
U7-15 activates U5G which applies a low to the antenna
tune (ANT TUNE) line. A low on the ANT TUNE line
enables the radio to key the transmitter on the selected

channel at a low power level (approximately 3 watts).

5.3.6.2 When the radio is in the receive mode, 3.3 V is
applied to the ANT TUNE line by the radio if

a B channel is being received. If an A channel is being
received, 12 V is applied to the ANT TUNE line. U5F is
activated by the 12 volts applied during A channel
reception; U5F is deactivated when 3.3 volts is applied

~.,-,)

during B channel reception. The logic high at U8-33
produces a low at U7-12 that enables the transmission

gate in U9 to apply the output voltage ofU5F to U8-31.

The output of U5F is 0 V when an A channel is selected,
5 V when a B channel is selected.

5.3.6.3 When the tuner is not in a tuning sequence, a
transition in the voltage level at U8-31 is an in-

dication of a channel change from an A to a B channel
or vice versa. This initiates a tuning sequence for the

newly selected channel.

5.3.7 Voltage Control and Regulation

The voltage control and regulation circuit con-

sists of Q23, Q24, and U4. Final voltage regulation is
provided by U4.

5.4.2

Initialization and 4:1VSWR Detection

The microcomputer applies a low to U8-33 to

produce an 0.4 volt signal at the ANT TUNE line. The
radio is enabled in the tune mode and generates an on-

channel signal at approximately 3 watts. If the VSWR is
greater than 4: 1, U6C applies a high to U8-39 and the
microcomputer begins the 4: 1 VSWR tuning sequence.
If the VSWR is less than or equal to 4: 1, U6C applies a
low to U8-39 and the tuner retains the tuning elements
in the current configuration until a channel change oc-

curs.

5.4.3

4:1VSWR Tuning Sequence

The microcomputer begins a sequence of switch-
ing tuning elements in and out of the rf line. During the
tuning sequence, the microcomputer monitors the
voltage level at U8-1 and U8-39. When a 4:1 match is
achieved, a low is applied to U8-39. A list of tuning
elements '3lsed to achieve the 4:1 VSWR is stored in the
microcomputer memory, and the microcomputer begins
the 2: 1 VSWR sequence. If a 4: 1 VSWR cannot be
achieved, the tuner reverts to the tuning configuration
previously stored in the microcomputer memory and

begins the termination of tuning sequence.

5.4.4 2:1 VSWR Tuning Sequence

U8-31 goes high to turn U5B on. If the VSWR is
greater than 2: 1, U6C applies a high to U8-39 and the
microcomputer begins a sequence of switching tuning
elements in and out of the rf line. (If the VSWR is less
than 2:1, the 1.5: VSWR tuning sequence is initiated.)
During the tuning sequence, the microcomputer
monitors the voltage level at U8-1 and U8-39. When a
2:1match is achieved, U6 applies a low to U8-39. A list
of tuning elements used to achieve the 2:1 VSWR is
stored in the microcomputer memory, and the
microcomputer begins the 1.5:1 VSWR sequence. If a
2:1 VSWR cannot be achieved, the tuner reverts to the
tuning configuration previously stored in the microcom-
puter memory and begins the termination of tuning se-
quence.

5.4.5

1.5:1 VSWR Tuning Sequence

5.3.8

. MicrocomputerU8 controls the operation of the

Microcomputer

automatic antenna tuner. All of the programs that con-
trol tuner operation are stored in the microcomputer on-
board memory.

5.4 SEQUENCE OF TUNER OPERATION

- 5.4.1 Power Applied

)

-,.:7 When dc power is applied to the SWITCHED
A + line (GRN), the microcomputer is reset.

U8-31 goes low to turn U5B off, and U8-32 goes
high to turn U5C on. If the VSWR is greater than 1.5:1,
U6C applies a high to U8-39 and the microcomputer
begins a sequence of switching tuning elements in and
out of the rf line. During the tuning sequence, the

microcomputer monitors the voltage level at U8-1 and
U8-39. When a 1.5:1 match is achieved, U6 applies a

low to U8-39. A list of tuning elements used to achieve
the 1.5:1 VSWR is stored in the microcomputer
memory, and the microcomputer begins the termination
of tuning sequence. U8-32 goes low to turn U5C off. If
a 1.5:1 VSWR cannot be achieved, the tuner reverts to
the tuning configuration previously stored in the

5

microcomputer memory and begins the termination of
tuning sequence.

5.4.6 Termination of Tuning Sequence

U8-33 goes high to allow the radio to revert to
the receive mode. The microcomputer memory retains a
list of the circuit elements that were switched in when

the sequence ended. Circuits elements remain selected
until there is a voltage transition at ANT TUNE (VIa),
SWITCHED A + (GRN), or CHANNEL CHANGE
(BLU). Tuner operation following these transitions is
described in the following paragraphs.

5.4.7 Transition At ANT Tune (VIa)

A voltage transition on the ANT TUNE line in-
dicates a change in radio channel from an A channel to
a B channel, or vice versa. The voltage transition is ap-
plied via U5F and U9 to U8-1I. All tuning elements are
switched out and the microcomputer begins initializa-

tion and 4: 1VSWR detection.

5.4.8 Transition At SWITCHED A + (GRN)

If voltage is removed from the SWITCHED A +
line, the list of selected circuit elements stored in the

microcomputer memory is lost. When power is reap-

plied to the SWITCHED A + line, the microcomputer is

reset and the initialization and 4:1VSWR detection pro-
cess begins.

5.4.9 Transition At Channel Change

When a channel is changed using the channel"-~

selection knob on the radio, a positive going pulse is ap- .
plied to the CHANNEL CHANGE line (BLU). A low is
applied to U8-34 and U8-39 to inhibit tuning until chan-
nel selection is complete. One-half second after channel
selection is complete, there is a low to high transition at
U8-34 and U8-39 and a high to low transition at U8-28.
The microcomputer then goes through initialization and

4:1VSWR detection.

5.4.10' Tune Power Variations

5.4.10.1 If, during a tuning sequence, the tune power
level falls below 1 watt or rises above 6 watts

for more than two seconds, the tuning sequence is stop-
ped. The tuner reverts to the circuit configuration pre-
viously stored in the microcomputer memory. This con-

figuration:y> used for antenna matching until there is a
channel change and the tune power is between I and

6 watts. When these two conditions are met the
microcomputer goes to initialization and 4:1 VSWR

detection.

5.4.10.2 If tune power falls outside the 1to 6watt range

for less than 2 seconds, the microcomputer

resumesthe tuningsequencethat was underway prior to 0""""

the level change. (,.)'

)

'I
j

1

.~

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i

TUNER DOES NOT

INITIATE TUNING SEOUENCE
WHEN RADIO IS SWITCHED
ON AND VSWR > ~:1

TUNER DOES NOT
INITIATE TUNING
SEOUENCE WHEN
RADIO CHANNEL

IS CHANGED AND

VSWR > ~:I

TROUBLESHOOT VSWR
DETECTOR CI RCUIT

CHECK SWITCHED
A+ CIRCUIT IN
RADIO

REPLACE FUSE

TROUBLESHOOT
VOLTAGE REGULATOR

CIRCUITS

YES

YES

NO

NO

TROU8LESHOOT
TUNE POWER DETECTOR
AND VSWR DETECTOR

NO

TROUBLESHOOT
ANT TUNE LINE
CIRCUIT IN

RADIO

f

DISCDNNECT PA
DlSA8LE/CHANNEL
CHANGE CONNECTIO
FROM RADIO

GROUND THE PA
DISA8LE/CHANNEL
CHANGE LINE (Bll
CHECK VOLTAGE
AT U8-28, 34, 38

TUNER CHANNEL CHA

CIRCUIT IS OPERATIN(
PROPERLY. CHECK
RADIO CHANNEL
CHANGE CIRCUIT.

CHECK CHANNEL
CHANGE CI RCUIT

IN RADIO

CHECK RESET
CIRCUIT (Q23, Q2~)

CHECK TIMING
ELEMENTS: C30,
C3I, C32, AND YI

NO

NO

NO

REPLACE U8

RELAY AND RELAY DRIVER.
TEST PROCEDUR E

I. GROUND TPI2 (RUNfTESn.

VERIFY THAT RELAYS K1-K5
ARE CLOSED.

2. GROUND TPII (ELEMENTS IN/
OUT) AND TP12 (RUNfTEST).
VERIFY THAT RELAYS K6-K21
ARE CLOSED, AND KI-K5 ARE
OPEN.

3. INDIVIDUALLY CHECK EACH
RELAY 8Y:

- DISCONNECTING EITHER

END OF L9.

- APf'L YING 13.8 V TO THE

SWITCHED A+ INPUT (GRN).

- GROUNDING THE APPROPRI-
ATE TEST POINT TO ACTIVATE

RELAY (TPI-TPS, TP17-TP28).

4. RECONNECT AND SOLDER La. RE-
MOVE GROUNO FROM TPII AND
TPI2.

VSWR DETECTOR TEST P

I. CONNECT RF OUT TI

ANTENNA OR DUMM

2. APPLY +5 V TO TP13
SLOW TUNING MODE
AT 2 Hz RATE).

3. TURN ON RADIO TO
SWITCHED A+ TO TU

~. MONITOR VOLTAGE

ANDJ8-39. VOLTAG
SHOULD GRADUAlL
TUNING SEOUENCE

CONDITION IS APPR'

SHOULD 8E lOW fO

1 SECOND DURING 1

OESNOT

TUNING

:EWHEN

-jANNEL
iED AND

4:1

TUNER DOES
INITIATE TUNING
SE~UENCE WHEN
RADIO IS TURNED
ON, BUT FULL POWER

VSWR > 4:1

CTPA

'HANNEL

JNNECTION

10

THEPA

'CHANNEL

LINE (BLUI
OLTAGE
3,34,38

'NELCHANGE
)PERA TING

:HECK
/NEL

'CUlT.

NO

NO

TROUBLESHOOT
CHANNEL CHANGE
CIRCUIT IN TUNER

PERFORM VSWR
DETECTO R TEST
PROCEDURE

NOTOK

YES

NOTOK

REPLACE ANY BAD
RELAY OR DRIVER

TROUBLESHOOT
PHASE DETECTOR
CIRCUIT

7

oEEPS-30866-0

TROUBLESHOOT
TUNE POWER DETECTOR
AND VSWR DETECTOR

NO

CH ECK TUN [
CIRCUIT IN ,

JR TEST PROCEDURE

RF OUT TERMINAL TO

OR DUMMY LOAD.
v TO TP13 TO ENABLE

ING MODE (SWITCHING

;TEl.

RADIO TO APPLY

A+ TO TUNER.

vOLTAGE AT UB-11
!, VOLTAGE AT UB-11

RADUALL Y DROP OURING

'QUENCE AS MATCHED

, IS APPROACHED. U8-39

, LOW FOR APPROXIMATELY

JURING TUNING SEQUENCE.

PHASE DETECTOR TEST PROCEDURE

1. DISCONNECT ANTENNA FROM RF
OUT TERMINAL

2. (T196OA ANO T1962A MODELS ONLY)
CONNECT A 560 PF CAPACITOR FROM

RF OUT TERMINAL TO GROUND.

3. GROUND TP1 1 AND TP12. UNSOlDER
AND REMOVE EITHER END OF R112.

4. APPLY 3 WATT RF SIGNAL TO RF IN-

PUT TERMINAL

5. VARY FREOUENCY OF RF INPUT,
MEASURE VOLTAGE AT UB-I. VOL-
TAGE SOULD BE LOW WHEN INPUT
FREOUENCY IS BELOW 6.5 MHZ, AND
HIGH WHEN INPUT FREQUENCY IS
ABOVE 7.5 MHz.

6. RECONNECT AND SOLDER R112. RE-
MOVE GROUND FROM TP11 AND TP12.

.----- -------

---

--

\

\

\

\

\

. K"

~OTE"

L29

<

UO

"

"

" /

\ KI2
(NOTEII

/

/ j

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KI3

INOTEIII

.,

: \

I \

\

\

-

I

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I

l

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RF OUTPUT

NOTES.

I. MOUNTE 0 ON

SOLDER SIDE
OF BOARD.

-----

:OMPONENT SIDE

~ BOARD DETAIL

- --- --- -- - - - - J

j

I

)

/

COMPONENTSIDE- BO-EEPS-302'4-0

/

SOLDER SIDE- BO-EEPS-3025'-0

OL-EEPS-302"-'

/

/

RF 'N

;- --- - - -- - --- -.. -. -- -

I

i

-

/

L-

r

- ".-- --- -.- --

(

~

'1.

,

SWITCHED A+

PA D'SABLE/

CHANNEL CHANGE

lard Detail and

Ust and

'-3lJOO-A

A NT TUNE

CONNECTED

NOT

j

I

\

\

\

\

\ ..

\

.~ - - -- - --- - -- -- --- -- ---

U4

SHOWN FROM COMPONENT

RF BOARD CIRCUIT BOARD

Rr

INPUT

. -"'-.

PHASE DETECTOR

.J.U.

{

ov

WAVEFORM AT U2.13 HAS SAME PHASE AS RF
INpUT CURRENT. OUTPUT OF U20 IS A SOUARE

WAVE.

0.9V-,-

-+....

O.ZV TO 1.0VP'p T

-*-

j\!\!\,

NOTE5

0.2VTOt.6VP'P:'/\/\/ ~

CHA~~E~ I~~:~~ >BLU

PULSE APPLIED BV RADIO WHEN CHANNEL IS"
CHANGED BYCHANNEL SELECTOR SWITCH.

s.OV-~

'.3V-

ANT TUNE} vIa

IGNITION A', "'HT

<NOTUSED>

SWITCHEDA+ ,.GRN

C169 -

.I

.os I

R97

II<

R98

II<

R99

II<

RIOO

tl<

.05

WAVEFORM AT UI.SHAS SAME PHASE AS RF .LCISS .LC168
INPUTVOLTAGEOUTPUTOFUIDISASOUARE

NOTE 5

DURING CHANNEL CHANGE PULSE O32/S OFF.

033 IS ON. CI82 IS CHARGING; 028-030 ARE

TURNED ON APpL YING A LOGIC LOW TO U8-34

AND U/!-39TO 'NHIBIT THE START OF THE TUN.

ING SEOUENCE DURING CHANNEL CHANGE

APpROX,MA TEL Y 0.5 SEC AFTER THE FALLING

EDGE OF THE CHANNEL CHANGE PULSE CI82

IS SUFFICIENTL Y DISCHARGED TO TURN OFF

028.030.

0.4 V DURING TUNiNG SEQUENCE

""- 3.3 V DURING RECEpTION OF B CHANNEL

\...l. 12 V DURING RECEPTION OF A CHANNEL

~

30

_C16'

1.01

WAVETHATISAPPUEDTOU3CLOCKINPUT.- -

S'"
A'

_C81

10.2'

L9

~

30
VR'
,OV

RAS

--

ISO1CA'

CR. 1.05

R12S

'7

R~

IK

7.

' ""

0.75 At1F'"

Rl10
~

.TI<

.05

1

CHANNELCHANGE CIRCUIT ~IT s

.SV

..

- - -+- - - --

'SV

.05 0.9V-,

1

029
M9642

RI20

~

10K

RI"

----..

IOK

Rl"

10K

031
M9642

030

M9642

,sv

JRJ8

_C'7

1.05

VOLTAGE CONTROL AND REGULATION

VRI9

S.IV

VRIT

S.6V

mm

'sv

tR27

'.7K

t:-

1.001

10K

TPI'

.S\A TO

~o~~~::s

L2 = TO
~UI-I
100 .LCT UI-IS

L3 1:.05 TO

loa

LA2 = TD
~U8-'0

'5Y =

RI.

2.2K

- - -

1.05

CIJ u,-.s

1.05

1..7

D

U3 FUP-FLOP OUTPUTS
USD OUTPUT IS LOW I
CAPACITIVE. USD OUTP,
PHASE IS INDUCTIVE.

VOLTAGE ACROSS CI2
THE FORWARD POWER
PUT. VOLTAGEISAPPu/

U'-I

R32

1.51<

VOLTAGE ACROSS
THE REVERSE pOw
VOL TAGE ISAPPLIE

B

nna Tuner

-am

EPS-30253-A

DURING CAP PHASE

U6-9, 3.2 V
U6-&4.' V

DURmG IND PHASE

U6-9,4.' V
U6-8' 3.2 V

...

".

:.51<

I

"Z 1

.51<IC"'

; .001

PUTS ARE APPLIED TO U6D.
ow IF RF INPUT PHASE IS

JUTPUT IS HIGH IF RF mpuT

.'"

OSS CI1 IS PROPORTIONAL TO

POWER A7THE RF TUNER INPUT.

'PLIED VIA L7 TO U6C.

B

C12 IS PROPORTIONAL TO
WER AT THE TUNER RF IN.
'PLIED VIA R34 TO U6C.

"ANNEL CHANGE, 0 V

VSWR DETECTOR

c.

'5V

1m

'.71<

8P,

REVERSE
POWER
LEVEL

L7
100

I

J.001

R6
101<

--r

Q ..LC49J.001

R.5
.31<

<::).'"

use ON TO DETECT '.5" VSWR

4.3 V TO DETECT2,' VSWR. 0 VOTHERWISE

4.3 V TO DETECT 1.5" VSWR, 0 VOTHERWISE.

CRZ

C8

-if-

.7P,

CII

DURING TUNING SEOUENCE.' IF RF INPUT
DROPS BELOW' WATT, UB-Z GOES LOW TO

SASE VOLTAGE
'.4 V TO CLOSE RELA Y

0 no OPEN RELA Y

3.2VIFOI.'SOFF

D

R.

.......

18.

=TZ

r

,.05

R.

T

LI

IOO

'.71<

C.

CRI

c.

, CR3

CI

1.05

HP,

'SV

RZ7

'.71<

-c..

IFORWARDPOWER

J.001

C5
8PF'

AND azz

(VIA R8"

R7

101< OUTPUT OF U6C IS 5 V, UNTIL THE INPUT VSWR

IS THE SAME AS THE VSWR THA T THE TUNER
MICROPROCESSOR IS TUNING FOR, 4". 2". OR

'.5..1 AS DETERMINED SY U8-31. U8-32. WHEN
THE APPROPRIA TE VSWR IS ACHIEVED. ua..3IS

0 V.

\J. TUNE POWER DCTECTOR

LEVEL

RH

..

G

CAP. PHASE.. 0 V
IND. PHASE.. 5 V

SWA' c.o..L.L c. I

IOOOPF'

-:~~ : : ~

JD

~ -1-~..J _TP5

1

~

TO

R74

U8-'5

-w.
101<

RI27

R58

Z71<

'.3K

0 VWHEN RF' INPUT POWER IS SETWEEN , AND
. WA TTS. 5 VOTHERWISE.

..

F

G

TURN OFF USA, WHICH IN rURN srops THE
TUNING SEOUENCE. IF RF INPUT RISESASOVE
7 WA TTS. UB-' GOES LOW TO rURN OFF USA.
WHICH IN TURN STOPS THE TUNING SE.

OUENCE.

c

IOOOPF'

- -- Ki' E

~ ~

(VI< R85'

TO 018 AND all '" CI20/CZ5 ZI P20 VCc'O TO L4Z
TO 019 AND alz CZ50/C50 Z2 PZI P2536

'5V

RI28
'.71<

TO azo AND 013 C500/C'00 2. PZZ 'J/O C SHUNT
TO OZ I ANO alA CIOOO/CZOO Z. PZ'
TO aZ2 AND 0'5 CZOOO/CAOO .5 P24

RZ6
'.71<

USA

"',

0.2V

GROUNDING TPI1 AND TP,2 ENERGIZES ..

KB-K21 FOR SERVICING. .,

SW A' '510P'

_

c"' , : '8L H

1

.05' '0 \'\..J TP, U6-36VOLTAGE,

;D ;; O.BVTOENABLEO'B-OZ.

TO

U8-24

AND 021

TO aI 0--1l.!!.

TOa.----bJ.
TO al---'d
TOaz----1d
TOa.----b1.
TOa.----hi
TO05-----'=2.
TOO'----6.§.
TOa7--6L
TOa8-_L8

~ U8-;~-

R73 ANDazo

101< (VIA R8.

VOO Z6 VDD

. DET INF'D I TO

PDHER ACI< .. P 11

TUNED INPUT 39 T1

CHANNEL INF'D 28 PI I

TUNE 33 P 16

O.BVRELA Y CLOSED

13.B VRELA Y OPEN

E

C.2.L ..Lc..

r - -- 1<2' ...!:.

L -1--f 0 VTOENABLE011-075

7.Z0 EA.VSS.PI0.PI2.PI3

510P'

~ ~

5.8...10.I1.Z5 NOT L;

.8 PZ7
37 PZ'
I Z DBO
13 OBI

" DBZ

15 DB'

16 DB.
11 OB5
18 OB.
!.!

. RESET

XTALI Co

XTAUI3

U8

INT~T F'AST/SLO.

VCC27.2..30 TD '5V

'5V

P15[3Z

p"l31

C3

5:"5A5I<HZ'=

1~Pf' 1

~

~~I I

R25
..71<

ELEMENTS

INIOUT

1.511 VSWR

'5V ...

I.05

AIB

2"

VSHR

R23 p

'.7K L

10

C4Z

"I

H

TUNE LINE CIRCUIT

VRI

3..31<

M

IF AN A CHANNEL IS SELECTED, THE RADIO Ap.

PLIES A + TO THE ANT TUNE LINE. U5F APPLIES
A LOGIC LOW TO U8.3,. IF A B CHANNEL IS
SELECTED ANT TUNE LINE VOLTAGE IS LOW,
U5F A PPLIES A LOGIC HIGH TOUB.3,.

WHEN U8-33 GOES LOW. U7.15 GOES HIGH.
HIGH IS APPLIED TO usa. usa APPLIES A LOW

TO ANT TUNELINE TliJACTIVA TE RADIO TUNE

MODE.

-6

GROUNDING TP12 ENERGIZES K,,"5. AND DE.

K

ENERGIZES KB-K15 AND K21 FOR SERVICING.

1.3.5.9

~

U7E

D.' V "ELA Y CLOSED

13.' V "ELA Y OPEN

E

>,

~

tP6

I

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