Harris Fm-10h3 User manual

FM-10IIJ

lOKW

l'M

'l'AANSMl'l"l'I!:R I

"

- '.

HARRIS

GATES

DIVISION

Im'IM

IlIlmlype

Corporation

WARRANTY

Seller

warrants

new

equipment

manufactured

by

Gates

Division

of

Harris

Intertype

Corporation

against

defects

in

material

or

workmanship

at

the

time

for

delivery

thereof,

that

develop

under

normal

use

within

a

period

of

one

year

(6

months

on

moving

parts)

from

the

date

of

shipment,

of

which

Purchaser

gives

Seller

prompt

written

notice.

Other

manufacturers'

equipment,

if

any,

including

electron

tubes

,

and

tower.;

shall

carry

only

such

manufacturers'

stand-

ard

warranty.

Seller's

sole

responsibility

for

any

breach

of

the

foregoing

provIsion

of

this

contract,

with

respect

to

ony

equip-

ment

or

parts

not

conforming

to

the

warranty

or

the

description

herein

contained,

is

at

its

option,

(a)

to

repair

or

replace

such

equipment

or

parts

upon

the

return

thereof

f.o

.b.

Seller's

factory

within

the

period

aforesaid,

or

(b)

to

accept

the

return

thereof

f.o.b.

Purchasers's

point

of

installation,

whereupon

Seller

shall

either

(1)

issue

a

credit

to

Purchaser's

account

hereunder

in

an

amount

equal

to

an

equitable

portion

of

the

total

contract

price,

without

interest,

or

(2) if

the

total

contract

price

hos

been

paid,

refund

to

Purchaser

an

equitable

portion

thereof,

without

interest.

If

the

Equipment

is

described

as

used,

it

is

sold

as

is

and

where

is.

If

the

contract

covers

equipment

not

owned

by

Seller

at

this

date

it

is

sold

subject

to

Seller's

acquisition

of

possession

and

title.

Seller

assumes

no

responsibility

for

design

characteristics

of

spp.cial

equipment

manufactured

to

specifications

supplied

by

or

on

behalf

of

Purchaser.

Seller

shall

not

be

liable

for

any

expense

whether

for

repoirs,

replacements,

material,

service

or

oTherwise,

in-

curred

by

Purchaser

or

modifications

made

by

Purchaser

to

the

Equipment

without

prior

written

consent

of

Seller.

EXCEPT

AS

SET

FORTH

HEREIN,

AND

EXCEPT

AS

TO

TITLE,

THERE

ARE

NO

WARRANTIES,

OR

ANY

AFFIRMATIONS

OF

FACT

OR

PROMISES

BY

SELLER,

WITH

REFERENCE

TO

THE

EQUIPMENT,

OR

TO

MER-

CHANTABILITY,

INFRINGEMENT,

OR

OTHERWISE,

WHICH

EXTEND

BEYOND

THE

DESCRIPTION

OF

THE

EQUIPMENT

ON

THE

FACE

HEREOF.

RETURNS

AND

EXCHANGES

Do

not

r~turn

any

merchandise

without

our

written

approval

and

Return

Authorization.

We

will

provide

special

ship-

ping

instructions

and

a

code

number

that

will

assure

proper

handling

and

prompt

issuance

of

credit.

Please

furn-

ish

complete

details

as

to

circumstances

and

reasons

when

requesting

return

of

merchandise

.

Custom

built

equip

-

ment

or

merchandise

specially

ordered

for

you

is

not

ret

l

Jrnab

l

e.

Where

return

is

at

the

request

of,

or

for

the

con

-

venience

of

the

custOr.ler,

a

restocking

fee

of

15%

will

be

charged.

All

returned

merchandise

must

be

sent

fre

i

ght

prepaid

and

properly

insured

by

the

customer.

When

writingto

Gates

Division

of

Harris

Intertype

Corporation

about

your

order,

it

will

be

helpful

if

you

specify

the

Gates

Factory

Order

Number

or

Invoice

Number.

WARRANTY

ADJUSTMENTS

In

the

event

of

equipment

fai

lure

during

the

warranty

period,

replacement

or

repair

parts

may

be

provided

in

ac-

cordance

with

the

provisions

of

the

Gates

Warranty.

In

most

cases

you

will

be

required

to

return

the

defective

merchandise

or

part

to

Gates

f.o.b.

Quincy,

Illinois

for

replacement

or

repair.

Cost

of

repair

parts

or

replacement

merchandise

will

be

billed

to

your

account

at

the

time

of

shipment

and

compensating

credit

will

be

issued

to

off-

set

the

charge

when

the

defective

items

are

returned.

MODI

FICATIONS

Gates

reserves

the

right

to

modify

the

design

and

specifications

of

the

equipment

shown

in

this

m:Jnual

without

notice

or

to

withdraw

any

item

from

sale

provided,

however,

thai

any

modifications

shall

not

advelsely

affect

the

performance

of

the

equipment

so

modified.

DAMAGES

AND

RISK

OF

LOSS

Purchaser

assumes

all

responsibility

for

and

risk

of

loss

of,

or

damage

to,

the

Equipment

upon

delivery

at

Seller's

shipping

point,

notwithstanding

the

fact

that

Seller

may

have

selected

the

carrier.

In

no

event

shall

Seller

be

liable

under

any

provision

of

this

contract

for

loss

of

business

or

of

anticipated

pro-

fits

by

Purchaser,

outlays

by

Purchaser

in

anticipation

of

business,

other

incidental

or

consequential

damages

on

account

of

neg

I

igence.

Purchaser

agrees

to

indemnify

Seller

against

all

claims,

whether

on

account

of

negligence

or

otherwise,

except

those

asserted

by

Seller's

employees,

arising

out

of

or

resulting

from

the

erection,

operation

or

use

of

the

Equip-

ment.

t;'

ARRIS-INTERTYPE

CORPORA~'"

GATES

DIVISION:

123

HAMPSHIRE

STREET'

QUINCY.

ILLINOIS

62301.217-222-8200

INSTRUCTION BOOK ADDENDUM

EQUIPMENT:

_--,

F

:;,,:

M=1

:....:.

0=H

=-

3

________

---'-

__

_

SERIAL

NO. 89293

I.

B.

NO.8

=-8

~

8~-

__

=

10

~

7

~

0

_

-0

=

0

=

1

~

___

_

DATE:

__

~

1

~

-1

=

8

~

-

~

7

=

4

____

__

_

It has

always

been the

policy

of

the

Gates

Radio Com

pany

to

give

our

customers the

advantage

of

the latest

product

improvements. This

addendum

insures

you

that

the

latest improvements have been

incorporated

in

your

equipment. This

way

we

can

provide

up

to

date

information

without

a

delay

due

to

printing

new

instruction

manuals.

Please

make

the

necessary corrections as listed

below.

Please

use

ink

for

a

permanent

record.

This

addendum

may

be removed

after

corrections have been made.

Thank

you

for

your

cooperation.

Page/Drawing No.

110-0253-233

Changes

R53

changed

from 100 ohm, 1

watt

to

51 ohm, 1

watt

for

proper

operation

of

the

P.A.Overload.

The

screen

bypassing

has

been

increased

to

5500

pf.

A 8

mfd,

4KV

capacitor

was

added

from

the

PA

screen

to

grid.

Full

winding

used

on

T3

secondary

of

Bias

supply.

R40

was

changed

to

(2)

1000 ohm, 10

watt

resistors

in

parallel.

A 8

mfd,

4KV

capacitor

was

added

in

parallel

with

C44.

R47

was

changed

to

10K

ohm, 225

watt

for

TPO

of

8000

watts.

6K

ohm,

tap

used

on

R45

for

TPO

of

8000

watts.

A

2K

ohm, 20

watt

resistor

was

added

from

R26

to

ground.

R39

in

the

AFC

Unit

changed

to

750 ohm, 1

watt

resistor.

I .

o

r-

o

888·

'070001

Price: $15.00

INSTRUCTIONS FOR

INSTALLING

AND

OPERATION

OF

GATES

FM-l0H3

-10

kW

FM

TRANSMITTER

Gates Radio Company

Quincy,

Illinois

SAFETY

NOTICE

WARNING:

THE

CURRENTS

AND

VOLTAGES

IN

THIS

EQUIPMENT

ARE

DANGEROUS

AND

UNDER

CERTAIN

CONDITIONS,

COULD

BE

FATAL.

This

Manual

is

intended

as

general

guidance

for

trained

and

qualified

installation,

operating,

maintenance

and

service

personnel

who

are

familiar

with

and

aware

of

the

dangers

inherent

to

handling

potentially

hazardous

electrical

and/or

electronic

circuits.

It

is

not

intended

to

contain

a

complete

statement

of

all

safety

precautions

which

should

be

observed

by

personnel

in

using

this

or

other

electronic

equipment.

THE

INSTALLATION,

OPERATION,

MAINTENANCE

AND

SERVICING

OF

THIS

EQUIP-

MENT

INVOLVES

RISKS

TO

BOTH

PERSONNEL

AND

EQUIPMENT,

AND

MUST

BE

PERFORMED

ONLY

BY

PROPERLY

TRAINED

AND

EXPERIENCED

PERSONNEL

EXERCISING

DUE

CARE.

PERSONNEL

MUST

FAMILIARIZE

THEMSELVES

WITH

SAFETY

REQUIREMENTS,

SAFE

HANDLING

AND

OPERATING

PRACTICE,

AND

PROCEDURES

(E.G.,

FOR

ELECTRICAL

BURNS

AND

ELECTRICAL

SHOCK).

Gates

shall

not

be

responsible

for

injury

or

damage

resulting

from

improper

installation,

operation,

maintenance

or

servicing,

or

from

the

use

of

improperly

trained

or

inexperienced

personnel

in

the

perform-

ance

of

such

tasks,

or

from

the

failure

of

persons

engaged

in

such

tasks

to

exercise

due

care.

As

with

all

electronic

equipment,

care

should

be

taken

to

avoid

electrical

shock

in

all

circuits

where

substantial

currents

or

voltages

may be

present,

either

thru

design

or

short

circuit.

Caution

should

also

be

observed

in

lifting

and

hoisting

equipment,

especially

regarding

large

structures,

during

installation.

LIABILITY

LIMITATION

The

procedures

outlined

in

this

Manual

are

based

on

the

information

available

at

the

time

of

publication

and

should

permit

the

specified

use

with

minimum

risk.

However,

the

manufacturer

cannot

assume

liability

with

respect

to

technical

application

of

the

contents

and

shall,

under

no

circumstances,

be

responsible

for

damage

or

injury

(whether

to

person

or

property)

resulting

from

its

use.

The

manufacturer

is

specifically

not

liable

for

any

damage

or

~nJury

arising

out

of

failure

to

follow

the

instructions

in

this

Manual

or

failure

to

exercise

due

care

and

caution

during

installation,

opera-

tion,

maintenance

and

service

of

this

equipment.

CAUTIONARY

NOTICE

Always

disconnect

power

before

opening

covers,

doors,

enclosures,

gates,

panels

or

shields.

Always

use

grounding

sticks

and

short

out

high

volt-

age

points

before

servicing.

Never

make

internal

adjustments,

perform

maintenance

or

service

when

alone

or

when

tired.

Never

remove,

short-circuit

or

tamper

with

interlock

switches

on

access

covers,

doors,

enclosures

,

gates,

panels

or

shields.

Keep away

from

live

circuits,

kno~y

your

equipment

and

don

I t

take

chances.

Proper

training

of

experienced

perso

nnel

and

observing

the

above

guidelines

will

help

assure

safe

and

continued

operation

of

this

equipment.

TABLE

OF

CONTENTS

SECTION PAGE

1.0

GENERAL

DESCRIPTION

..

..................

..

...........................

..

...........

1-1

1.1

Warranty

and

Safety Notice

..

................................................

1-1

1.2 Purpose

of

Book ...................................................................

1-1

1.3 Purpose

of

Equipment ...............

..

.......................................

..

1-1

1.4 Description ..........................................................................

1-'

1.5 Technical Data ...................................................................... 1-2

1.6 Vacuum Tube Table ...............................,............................. 1-3

2.0

INSTALLATION

..............................................................................

2-1

2.1

In

spec

tion .

....

.......

..

.........

...

..

............

....

........

..

..............

..

......

2-1

2.2 Tube Handling

and

Operation Precautions ............................

2-1

2.3 Packing Check List ..........................................

....

.........

..

...

..

.

2-1

2.4 Installation .................

..

.............................................

..

......

...

2-2

2.5 Wiring Connection ............

..

.................................................. 2-3

2.6 Cooling ................................................................................. 2-4

3.0 OPERATION ...........................:.......................................................

3-1

3.~

Pre-Operation ......

..

....

................

..

....................

..

........

...

..

3-1

3.2

TestData

..............................................................................

3-1

3.3 Adjustment .............

...

..

........

..

......

...............

......

.................

3-1

3.4 Maintenance

..

....................................................................... 3-3

4.0

CIRCUIT

DESCRIPTION ................................................................

4-1

4.1

Power

Amplifier

..

.............

...

..

......

..

......................

..

.......

...

.....

4-1

4.2 IPA

..

.....

..

..............................

..

........

..

......

..

......

..

....

..

.

..

.....

..

.

..

4-1

4.3 Exciter .....

..

...

..........

...

.......

...

........

..

....

...

.......

..

................. 4-2

4.4 Power

Supply..............

...

..........

...

............

....

......................... 4-2

4.5 Control Circuits .................................................................... 4-2

4.6 Metering ................................................................................ 4-3

5.0

ADDITIONAL

INFORMATION

......................................................

5-1

5.1

Remote Control ................

..

...

..

....

......

.....

...

....

..

...

.

..

............

5-1

5.2 Stereophonic Operation ............

....

..

.....

..

...

..

....

.

..

...............

5-1

5.3 Second Harmonic

Filter

........:..................

..

............................

5-1

6.0 PARTS LIST ....................................................................................

6-1

0

r--

0

-------------~---------

SECTION

PAGE

7.0

ILLUSTRATIONS

Block Diagram 814 6639

001

PA

Efficiency Curve 814 1920001

PA

Coarse

Tuning 814 1733001

Installation Details 838 1602001 0

--.J

0

Low

Pass

Filter

814 8556

001

2nd Harmonic

Filter

814

8554001

Overall Schematic 852

6711

001

8.0 FM

EXCITER

ii

SECTION 1 -

GENERAL

DESCRIPTION

1.1

WARRANTY

AND

SAFETY

NOTICE

This

equipment

is

guaranteed

under

the

liberal Gates

Warranty,

terms

and

conditions

of

which

are

explained

in

the

standard Gates

Warranty

which

is

printed

inside

the

front

cover

of

this

manual.

Most

Gates

manufactured

items are guaranteed

for

one year,

with

the

exception

of

tubes and

moving

parts,

which

are subject

to

specific

warranties

based

upon

hours

of

usage.

The

Warranty

does

not

extend

to

"no

charge"

service in

the

field.

Switch

to

Safety

-

This

equipment

employs

voltages

which

are dangerous and

may

prove fatal

if

contacted

by

operating

personnel.

Extreme

caution

should

be

exercised

when

working

wlth

the

equipment.

Observe safety regulations.

Do

not

change

tube

s

or

make

adjustments

inside

equipment

with

any

voltages

ON.

While

your

Gates

transmitter

is

fully

interlocked

you

should

not

rely

on

the

interlock

switches

for

removing high

operating

voltages.

It

is

always best

to

disconnect

the

primary

power

at

the

building

wall

switch

and discharge all

capacitors

with

the

grounding

stick

provided.

1.2 PURPOSE

OF

BOOK

This

instruction

book

has

been prepared

to

assist in

the

installation,

operation,

and maintenance

of

the Gates

FM-10H3

10

kW FM

transmitter.

1.3

PURPOSE

OF

EQU.IPMENT

The

Gates

FM-10H3

is

an

FM

broadcast

transmitter

with

10 kW

watt

s

output

delivered

to

the

transmission line.

The

operating

frequency

is

88-108

MHz.

with

characteristics exceeding those required

by

the

Federal

Communications

Commission

for

standard

FM

broadcast service.

The

transmitter

is

designed

for

continuous

broadcast

operation

and consists

of

the

exciter,

intermediate

power

amplifier,

and

the

power

amplifier,

plus

their

associated

power

supplies.

1.4

DESCRIPTION

Only

one

cabinet

is

required

to

house

the

entire

transmitter.

This

cabinet

is

42"

wide

x

78"

high x

32-%"

dee

p.

All

necessary

met

eri

ng

is

provided

by

four

meters located on a

meter

panel

at

the

top

of

the

cabinet. Ready access

to

the

complete

transmitter

is

accomplished

by

a removable rear

door,

a hinged

access

panel, and a

drop

cover

of

the

exciter

unit.

Front

doors

are

provided

to

offer

a pleasing and

symmetrical

front

view

appearance.

The

following

controls

are located on

the

front

panel:

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

(j)

(k)

Filament

ON

Filament

OFF

Plate

ON

Plate

OFF

Multimeter

Selector

VSWR Cal

PWR

Cal

FOR

PWR/vSWR

CALlVSWR

Selector

IPA Screen

Control

PA Scroen

Raise/Lower

Control

PA

Fil

a

ment

Control

1-1

1.5

1-2

(I)

Remote/Local Switch

(m)

PA

Plate Tuning Control

(n)

PA

Output

Loading Control

(p) I

PA

Plate Tuning Control

(r)

Plus

Five (5) Potentiometers for adjustment

of

PA

Plate

Current Remote Reading, Recycle Adjustment, I

PA

Overload,

PA

Plate Voltage Remote

ReacJing,

PA

Overload

TECHNICAL

DATA

Power

Output:

5

tp

10

kW

Frequency

Range:

88 to 108 MHz

RF

Output

Impedance: 50 ohms

Output

Termination: Standard E

IA

3-1/8"

Flange

Frequency Stability: ±.001%

Harmonic Attenuation:

-80

dB

Modulation Capability:

±100

kHz

Audio

Input Impedance: 600 ohms

Audio

Input

Level: +10 dBm,

±2

dB

Audio

Frequency

R'esponse:

±1 dB,

30-15,000

Hz

Audio

Distortion:

%%

or

less,

30-15,000

Hz

FM

Noise Level: 65 dB below 100% FM modulation

AM

Noise Level: 50

dB

below equivalent 100%

AM

modulation

Power'Source: 208/250 V., 3

Phase,

60 Hz;

115 V., 1

Phase,

60 Hz

Input

AC Power Requirement:

17

kW.

240 V. 300

W.

115 V.

Power Line Variation (Slow):

±5%

Power Factor: 90%

Altitude:

7500 feet

Ambient

Temperature

Range:

~20o

C

to

45

0 C

Maximum

VSWR

1.7

to

1

Overall Cabinet Size:

42"

W x

78"

H x 32%" 0 *

Weight: 825 pounds (Approx.)

Front

Door

Swing:

21"

* 32%"

is

overall depth dimension. With rear door,

front

door handles, and

meter~trim

strip removed minimum depth

is

29%".

---~I

0

-.J

0

o

r---

o

1.6 VACUUM TUBE TABLE

The

following

tubes

ar

e employed in the

transmitter:

SYMBOL

V-2

V-1

TUBE

TYPE

4CX300A

4CXlO,OOOD

FUNCTION

Intermediate Power

Amplifier

Power

Amplifier

1-3

o

r--

o

2.1

SECTION 2 -

INSTALLATION

INSPECTION

The

FM-lOH3

is

carefully packed at the Gates plant

to

ensure safe arrival at

its destination. The equipment

is

packed in a number

of

heavy cartons and

wooden crates. Open the crates and cartons carefully

to

avoid damaging any

of

the contents. Remove the packing material and search

for

possible small

items, such

as

pilot

lights,

fuses,

loose screws, and bolts.

If

damage should occur during shipment, all claims should

be

filed

promptly

with

the

transportation

company.

If

a claim

is

to

be

filed, the original pack-

ing

case

and material must

be

preserved. A damage report must

be

filed

to

collect

for

shipping damages. Gates Radio Company

is

not

responsible

for

damage occuring during shipment. Parts

or

components shipped

to

replace

those damaged in transportation

will

be

billed

to

the customer plus trans-

portation

expenses, the cost

of

which

should

form

a

portion

of

your

claim

to

the

transportation

company.

A complete visual inspection should

be

made

of

the equipment. Determine

that

there are no loose connections, loose components, broken insulators, etc.,

that

may have

been

damaged in shipment. Make sure all relay contacts are

free and in good mechanical

condition.

Make sure all mechanical connections

are

tight.

Check

with

a screw driver

or

·a wrench, all mechanical and electrical

connections

that

are mechanically bolted together.

All

tie downs

or

blocking

used

for

shipping purposes should

be

removed. A good overall visual inspec-

tion

may

save

time

and

trouble

in placing the

transmitter

into

operating

condition.

2.2

TUBE

HANDLING

AND

OPERATING PRECAUTIONS, 4CX10,OOOD

2.3

Avoid

bumping this tube. Due

to

its large

mass,

bumping this tube

will

introduce resultant

stresses

which may cause internal damage.

Before operating this tube, please refer

to

the tune-up and operating procedure

given in Section 3.

It

is

recommended procedure

to

adjust the

equipment

for

operation under heavy plate loading conditions, and

with

only

sufficient

RF

drive

to

provide the required power

output

and efficiency.

Extreme care should

be

taken during tune-up

as

well

as

in regular service

to

avoid,

even

momentarily,

operation

of

this tube under

conditions

of

insufficient

plate loading

or

excessive RF drive. These operating conditions, especially at

the upper end

of

the

VHF

range,

will

produce excessively high

seal

and/or

bulb

temperature and

will

result in damage

to

this

tube.

PACKING CHECK LIST

Certain components

of

the

transmitter

have

been

removed

for

shipment and are

packed separately

to

ensure safe handling. These parts on the

FM-l0H3

have

been

kept

to

a bare

minimum

and

are

plug-in units and heavy components.

Tubes

that

are

not

clamped

down

for

normal operation

are

also removed. The

following

components have

been

removed

from

the transmitter

for

shipping

purposes:

Quantity

Part Number

813

9383

001

374

0014

000

Description

Exhaust

Tubing

and 0 Rings (IPA)

Tube,

4CX300A

2-1

Quantity

1

1 Assy.

1

Part Number

3740077

000

5240029000

9423928002

992

1600001

472

0410000

Description

Tube,

4CX

10,0000

Capacitor, plug-in, C42

r\lotch

Filter

& RF Balun Assembly

Low

Pass

FiIter

Power Transformer,

T4

As various components are removed, the wires connecting

each

component

are

numbered

or

tagged

for

placement

of

these parts.

After

determining

that

all

these components are on hand, you are ready

to

proceed

with

the installation

in

an

orderly

manner.

2.4 INSTALLATION

2-2

In advance

of

actual placement

of

the equipment, certain planning should

be

accomplished. The

use

of

the installation drawing

will

assist

in locating the

power and audio

input

terminals

of

the transmitter.

Either side

of

the

transmitter

may

be

placed against a wall

or

other

equipment.

Complete accessibility

for

maintenance and installation

is

provided in the

/M-l0H3

by

a~cess

fro.m

t~e

front

or

t~e

rea~

of

the

transmitter

cabinet.

~stall

the plug-Ill capacitor

In

the

transmitter

bias supply.

Refer

to

the FM

Exciter

Installation Instructions

for

proper

module placement

in the exciter cabinet.

Unblock

the blower assembly.

Mount

the power transformer (T4) through the back

door

of

the transmitter.

It

would

be

wise

to

remove the ceramic fuse

block

temporarily

when doing this

to

prevent accidental damage

to

this part.

Orient

the transformer

so

that

the

secondary taps on the coils face inward. Connect the

primary

power leads

from

contactor, K2

to

marked terminals at the

top

of

T4. Select the proper taps on

the power transformer

T4

for

the

primary

line voltage. Secondary leads are

tag~ed

for

connection

to

their

proper taps

o~

the coils.

The RF

output

balun assembly installs

from

inside

the

transmitter

enclosure.

Before mounting,

temporarily

remove both

monitor

coupling loops

from

the

top

portion

of

the balun.

With

the inner

conductor

removed and the balun

sleeve

up,

bolt

the

unit

beneath the

top

of

the enclosure. Insert the inner

conductor

from

the

top.

Take the notch

filter

and thread the stud

from

the balun infler

conductor

into

the inner

conductor

of

the notch

filter.

Tighten

with

a crescent wrench

from

the loading capacitor connection in the

PA

enclosure. Slip the

filter

sleeve

down

over the

outer

conductor

and fasten securely

with

the stainless

steel clamp provided.

Remount the

two

monitor

coupling loops on the

exterior

vertical balun.

The lower end

of

the inner

conductor

of

the balun connects

to

output

loading capacitor C-6.

Loosen the

Allen

set screws on the adjustable

portion

of

the balun.

The

distance

that

this

component

is

positioned vertically

from

the tube deck

varies

with

operating frequency. Refer

to

your

test data sheets

for

the

proper measurement on

your

assigned channel. This adjustment must

be

accurate

within

1/8"

for

proper operation.

o

-...j

o

r---

o

The

4CX300/-,,\

IPA tube

has"

bl-eechblock

base.

The tube must

be

c()refully

installed

Lo

prevent dcllllrlgC to the contacts

of

the tube

or

its socket. The

tube must be seated

ovel-

the

CGnter

rod

of

the tube socket and posi tioned

in such a

way

that

the tube electrode rings are in

lille

with

the socket fingers.

After

the tube

is

pushed downward

to

the proper posi

lion,

rotate the tube

until

all the electrode rings have completely slipped between their associated

socket fingers.

Install the anode connector around the anode and tighten securely.

Drop

the

exhaust tube

through

the opening

of

the upper deck

to

the

top

of

the I

PA

anode connector.

Hold

the exhaust tube in place

with

0 rings above and

below the cleck surface.

Install the

4CXlO,000D

carefully in its socket and push

firmly

until

the tube

is

properly

seated_

The

anode connector assembly secures

with

a clamp

to

the

tube and

with

a

bolt

to

the plate line. Coarse frequency tuning

of

the plate

circuit

is

determined

by

the distance

of

the

rotary

section

of

the plate

circuit

from

the 4CX1

0,0000

tube deck. This measurement

is

recorded in the test

data

for

your

transmitter

and should

be

checked before operating the trans-

mitter.

Tolerance here

is

approximately

1/16".

Bolt

the

low

pass

filter

in the transmission line between the directional

coupler and antenna coax, and

your

basic installation

is

complete. Provisions

should

be

made at the transmitter site

to

have at least

two

supports

for

the

filter.

2.5 WIRING CONNECTION

After

the

transmitter

is

physically in place and the components removed

for

shipment have been re-installed, AC power should

be

brought

to the trans-

mitter.

The power

leads

from

the transm

i11el

shouid corne

from

a

low

reactance

power

source

of

either

208;

230,

or

240

volts, 60 Hz, 3 phase,

with

approximately

a

21

kVA

capacity. A power source

of

.115 volts,

60 Hz,

with

500

watts

capacity

is

also required.

Referring

to

the

installation drawing, the 240

Volt,

3

phase

input

enters the

transmitter in the

lower

right

hand corner and connects

to

the 3 phase fuse

block immediately

to

the

left.

A 115

Volt,

single

phase

fuse block

is

located at the center and

to

the rear

of

the

transmitter

with

the

input

termillals

for

the 115 Volts, single phase

towards the rear

of

the transmitter.

The audio

input

line enters the

base

of

the

transmitter

at

the center

approximately

T'h."

from

the

front.

The audio line connects

directly

to

terminal board TB-1

of

the FM Exciter. Terminals 1 and 3 are the audio

input

and terminal 2

is

ground

or

shield connection.

If

stereo

is

used

the

lines are connected in accordance

with

the

M6533

Stereo Generator instructions.

The

conduit

or

wiring

of

the power leads should

be

in agreement

with

local

electric codes and

be

able

to

carry the power requirements

of

the transmitter.

Power leads and program leads should

not

be

run in the

same

conduit

or

in the

same

wiring

duct.

If, due

to

necessity, the program

leads

are

in close

proximity

to

the power leads, the program leads should

be

separately shielded.

2-3

2.6

2-4

A good

wound

at these FM frequencies

is

nwndJtory

in keeping RF currents

in nearby <ludio equipment

to

a

minimum.

RF

lJsu811y

shows up ill one

of

two

ways

--

feedback

or

high noise, aile! in some

cases

both.

It

shollid

be

pointed

out

that even a

sm811

amount

of

unshielded

wire

makes a very

efficient

antellna

for

FM frequencies.

If

RF from the cabinet field

is

trans-

ferred to the audio equipment,

it

is

rectified and shows up

as

noise

or

feed-

back.

We

strongly recommend a single

common

ground

point

from

the

transmitter

base

to

a good grounding system, sllch

as,

a water pipe

or

actual

earthing ground.

COOLING

The

transmitter

is

air

cooled and

severClI

kilowatts

of

heat are developed and

dissipated through the air

outlet

in the

top

of

the transmitter. It may

be

necessary

to

provide a means

of

exhausting this air

from

the

transmitter

room

or

enclosure. Heat

is

a major

factor

to

electronic

component

deteriora-

tion. A good system

of

removing the heated

air

from

the

transmitter

and the

transmitter

room and providing cool air

for

the air

inlet

of

the

transmitter

will

greatly prolong the life

of

the transmitter and its components.

Duct

work,

if

installed, should

not

provide any back pressure

to

the power

amplifier

enclosure.

At

no

point

should the

duct

work

have

less

of

a cross sectional

area

than the opening at the

top

of

the transmitter. Sharp, right angle bends

are

not

permissible. Where

it

is

necessary

to

turn

a

right

angle, a radius

type

bend shou

Id

be

used.

There are many installation possibilities. Each and every installation

is

somewhat

different.

Therefore,

it

is

not

possible

to

give complete detailed

information

on the

transmitter

ducting.

Only

general

information

can

be

supplied! As a suggestion, contact a local heating and cooling

contractor

for

a detailed

Clnalysis

of

the problem.

After

the

transmitter

has

operated at

full

output

a number

of

hours a

temperature rise inside the transmitter

must

not

exceed a rise

of

206 C

above the ambient measured at the air intake

of

the blower and must

not

rise above 600 C under any circumstances (excluding PA

output

air).

20

0 C ::

6S

o

F,

60

0 C

::.

1400 F

I

o

'.J

o

r---

o

3.1

SECTION 3 - OPERATION

PRE-OPERATION

Before placing the

FM-10H3

into

operation, check once again the

points

covered in Section

2.

Have

you

mounted

all components physically and

made these electrical connections?

1.

Primary power

to

the

3 phase fuse block.

2.

115

Volts

to

the

1

phase

fuse block.

3. Program line connected

to

the

exciter.

4.

115

Volts

to

the exciter.

5.

Transmitter

connected

to

antenna

or

a suitable load.

If

everything appears

to

be

in order, then

you

may proceed.

3.2 TEST

DATA

Your

equipment

has

gone

through

many

different

kinds

of

tests at the

Gates

factory,

and

has

been

operated

for

several hours on

your

assigned

operating frequency. This

is

to

ensure

correct

adjustment and

proper

setting

of

all controls. Refer

to

the test data supplied

with

your

transmitter.

This data

is

attached

10

the

front

of

the

transmitter

when

shi'ppe~.

3.3 ADJUSTMENT

,

I

Set the dial settings

to

those given on the test data sheet.

Turn

the IPA

screen voltage

control

fully

counter-clockwise. Primary power may

now

be

applied

to"

the

transmitter

by

pushing the

filament

ON

button.

The

light

behind the

filament

ON

button

should light.

Next,

the

blower

should begin

to

run and come up

to

speed.

After

the

blower

reaches

maximum

operating

speed, air pressure in the PA enclosure

will

operate the air switch.

Run the PA screen voltage

control

to

the lowest

position

(counterclockwise)

on the screen rheostat.

Check the P.A. bias voltage and adjust

as

necessary

to

obtain

the test data

sheet measurements. During the tune-up procedure

it

may

be

necessary

to

increase the bias voltage

to

prevent the P.A.

from

drawing excessive plate

current. The grid bias voltage on the P.A.

is

a

combination

of

the developed

bias

frqm

the RF and the constant voltage

from

the bias supply.

The

bias

supply

is

set at a compromise

position

to

obtain

the iJesired power

output

and

to

keep

the

P.A.

within

its dissipation ratings in

case

of

RF failure.

Closing

of

the air switch

will

turn

ON the PA

filament

voltage

which

may

be

read

with

the

multimeter

switch on the meter panel in the

filament

voltage

position.

Set the

filament

voltage

for

7.5 voltst'

('

4n"'

r

-,{'-->:c

-'

.'l"-'--<l'"

Next,

place

the

multimeter

switch on the meter panel

to

thti[PA

cathode

current

position

(this

is

the

UP

positi·on).

If

the

exciter

is

delivering

power

to

the IPA stage, a reading

of

approximately

10%

will

be

read on

the

multi-

meter. As this meter

is

reading cathode

current

it

will

also read the grid

current.

3-1

fl,

3-2

The high voltage may

now

be

llpplicd

by

pushing the high voltage

Oi\J

button.

This supplies plate and screen voltage

to

the IPA stage simultaneously

with

the

applicJtion

of

plate ond screen voltage

to

the power amplifiel" staye. Bring the

screen

control

for

the IPA up un til the IPA cathode draws

approximately

50%

scale

readinrJ

on the

multirneter.

Resonate the IPA plate

circuit

by

tuning

for

a

dip

in the IPA cathode meter reading.

If

the plate

circuit

and loading are

near

th8ir

operating positions, power

output

of

the

amplifier

will

be

noticed.

During

the tune-up procedure

it

may

be

necessary

to

increase the IPA screen

voltage

to

prevent the P.A.

from

drawing excessive plate current.

Increase the screen voltage

of

the power

amplifier

by

bringing the screen

control

lever switch

to

the

UP

position

until

approximately

1.5 amperes power

amplifier

plate

current

is

indicated. Resonate the plate

circuit

of

the

pO\J\/er

amplifier

by

adjusting the plate

tuning

(L2)

for

a

dip

in plate current.

Next,

check the

position

of

the

output

loading

by

rotating

the

output

loading

control

to

give

a

maximum

output

indication.

The

power

output

meter

is

the farthest righ t hand meter on the meter panel.

Its

function

is

determined

by

the FOR PWR/VSWR

CAL!VSWR

Selector switch

(S

1)

located on the

upper

portion

of

the

access

door.

You

may read:

1.

Forward power.

2.

Meter

calibration

for

maximum

scale reading

during

VSWR measurements.

3.

VSWR on

the

transmittion

line.

Check the VSWR on

the

transmission line. Position the Power/VSWR

Selector

to

the VSWR Calibrate

position

and set the power

output

meter

for

full

scale

deflection

with

the VSWR

CAL

control.

Turn

the selector

switch

to'

VSWR and read

the

reflected wave.

Although

the transmitter

will

operate

into

a 1.7:1 mismatch

it

is

recommended

to

keep the VSWR

to

a

minimum.

If

a high VSWR

is

noticed

it

is

generally traced

to

the

transmission line

and/or

antenna problems.

Since the

transmitter

was checked

into

a 50

ohm

resistive load any system

with

a mismatch

will

probably

change the tuning. Therefore, the recorded

test'data

knob

readings

may

not

agree

with'

the actual

operation.'

If

it

is

1.5:1

or

better, the screen voltage

of

the P.A. and the IPA stage may

be

increased

until

both

are at

maximum

or

near

maximum.

The plate tuning,

output

loading, and IPA plate tuning should

be

adjusted

for

the

maximum

output

and the

most

overall

efficient

condition.

To

reduce the RF

output,

the

amount

of

drive

to

the

PA

can

be

decreased

by

lowering the screen

voltage

of

the IPA.

Also,

the

output

can

be

reduced

by

decreasing the PA

screen Voltage.

The

multimeter

switch

(S1O)

located on the meter panel

will

give

an

indication

of

the

amount

of

drive

to

the grid

of

the PA tube.

This

is

a relative indication

and

is

read

with

the

meter

switch in the DOWN position.

It

will

be

'noticed

that

maximum

drive

condition

will

be

very close

to

the same

point

of

the

IPA

plate

current

dip.

The

IPA plate tuning may, at some frequencies and power

levels,

be

different

for

maximum

output

and

for

minimum

IPA plate current.

A compromise should

be

made on the plate

tuning

of

the IPA

for

a

IPA

cathode

current

of

approximately

70% scale reading

with

a

minimum

or

dip

in tuning.

The

tuning

on

either

side

of

the

dip

may

affect

PA

efficiency

as

well

as

power

output.

o

-.....I

o

r--

o

The operation

of

the

transmitter

is

very simple and straight-forward, and

once adjusted should require

only

a nominal

amount

of

touching up the

tuning at regular maintenance periods.

The overloads are

set

for

correct operating level at the

factory.

The I

PA

plate overload

is

set

for

nearly

full

scale

reading on the

multimeter.

The

PA

plate overload

is

set

for

approximately

2.7 amperes plate current. The

adjustments

for

the overloads are 10catedunCfer a small cover plate located

on the

front

access

door.

They

may

be

referred

to

by

symbol numbers on

the schematic.

Power

output

of

the transmitter may

be

increased

or

decreased

by

three .

controls on the transmitter. The

first

is

the

output

loading.

It

is

best

to

"\

leave

this con.trol set

for

maximum

loading on the

amplifier

as

this

will

)

give more stable operation

as

recommended

for

any tetrode. The second

control

is

the power

amplifier

screen voltage.

After

the loading

has

been

adjusted

for

maximum

power·

output

the screen voltage may

be

raised

or

lowered

for

the desired operating power. The

third

control

is

the IPA

screen voltage

control.

Reducing this

to

its

minimum

value

will

reduce

the drive and

part

of

the bias

to

the final

amplifier

causing

it

to

overload

and

trip

the plate voltage.

It

may

be

operated in its

maximum

position

without

any detrimental

effect

s. However,

to

give partial

control

to

power

output

and some tolerance on the power

output

of

the IPA

stage,

it

is

recommended

that

it

be

run

at

approximately

80%

of

its full scale setting.

The

output

of

the exciter

is

adjusted

with

a

output

control

of

the 10

watt

amplifier

on the

exciter

and

is

covered in the FM

Exciter

section

of

this

manual.

The

transmitter

can

easily

be

remotely

controlied.

Description

of

the

connections

is

covered in Section

5.

Two

controls

for

setting the remote plate voltage and plate current

for

external metering are located under the cover on the hinged

access

door

and are shown by symbol numbers on the schematic

..

The screen voltage

of

the power

amplifier

is

motor

controlled

and

is

also

connected

to

the remote

control

Raise/Lower

function

for

power

output.

3.4

MAINTENANCE

Maintenance

of

the FM-10H3 should consist

of

the

following:

1.

Keeping the trans

mitter

clean.

2.

Changing tubes when

emissior.1

falls

off.

3. Checking mechanical connections and fasteners.

4. Lubricating the blower

motor.

Keeping the

transmitter

clean

from

the accumulation

of

dust

will

redl.J~e

failure resulting

from

arcing,

dirty

relay contacts, and overheating

of

chokes,

resistors, and transforme

rs.

Electrostatic fields

are

"dust

catchers".

Support

insulators in

the

PA enclosure and other locations

ar

e the worse offenders.

They must

be

kept clean and free

of

all foreign material at all times.

If

not,

arcing may result

ancJ

the insulator shattered.

3-3

3-4

The air

filter

should

be

clean at all times. The w(1silable air

filter

used

in the

back door may

be

purchased

from

the Gates Radio Company under Part

Number 827 5285 011. However, the filter may

be

clealled by using

wal

m

water and a mild detergent.

Once a

month

the entire transmitter should

be

cleaned

of

dust. The inside

of

the power

amplifier

should

be

thoroughly wiped

cleem

of

dust. A small

brush, soft

rag,

and vacuum cleaner

can

be

used

very effectively in keeping

the equipment clean.

All

contactors and relays should

be

-inspected regularly

for

pitting

and

dirt.

The contacts should

be

burnished

and

cleaned

if

required. The overload

relays are telephone type

with

sealed

contacts

and

should require

little

attention.

The bearings

for

the

motor

of

the PA blower are

sealed

and

normally give

long

trouble

free operation.

They

are lubricated

for

approximately 20,000

hours

of

operation.

Aft

er

this period

of

operation the

grease

in these bearings

should

be

changed.

Th

is

done by taking

Lhe

drain plug

out

of

the

bottom

of

the bearing and attaching a

grease

fiLting to the upper plug on the bearing.

New gr

ease

should be applied

until

clean

grease

runs

out

of

the drain pl

ug

at

the

bottom

. It

is

suggested

the blower

be

removed for this

ma

intenance.

The

PA

tube and the IPA tube should

be

removed once a month and the fins

cleaned

of

dust.

Air

may

be

blown through the fins in the

reverse

djrection

or

the anode cleaned

with

soap

and

water or denatured alcohol.

This transmitter

is

a precision electrical device,

and

as

such, should

be

kept

clean at all times

and

free

of

dust

and

foreign material. Dust

and

moisture

condensation

will

lead

to possible arc overs

and

short conductive paths.

A good preventive maintenance schedule

is

always the best assurance

for

trouble

free transmitter operation.

.\

o

r--

o

4.1

SECTION 4 -

CIRCUIT

DESCRIPTION

The

FM-10H3

circuits

will

be

described in the

following

sections:

Power

Amplifier

Intermediate Power

Amplifier

(IPA)

Exciter

Power Supply

Control

Circuits

Metering

POWER

AMPLIFIER

The power

amplifier

of

the

FM-10H3

employs a single

4CX.1

0,0000

tetrode

in a

common

cathode

amplifier

circuit.

The

plate

circuit

is

inductively

tuned

by

varying a length

of

inner

conductor

of

a transmission line

within

the rectangular

outer

conductor. The plate line

is

approximately

one-half

wavelength long, being fore-shortened by the

output

capacity

of

the tube.

The large variable

portion

of

the line

is

used

for

rough

or

approximate

frequency setting and the end

of

the half-wave line

is

made variable

for

plate

circuit

tuning. The end

is

controlled

from

the

front

panel.

The

fine

frequency

control

covers

approximately

3

MHz

at the

low

end

of

the FM

band and

approximately

6 MHz at the higher end

of

the band. .

Output

coupliny

is

accomplished by capacity tuning a balun. The balun

inductively

couples RF power

from

the

amplifier

enclosure.

The PA grid

circuit

is

common

with

the IPA plate

circuit.

Output

capacitance

of

tne I

PA

tube

with

the IPA variable plate inductance, L6,

and the

input

capacitance

of

the PA tube

form

a pi cirGuit. The position

and size

of

inductor

L10,

is

used

to

vary the IPA loading.

(A

small move-

ment

of

L10

will

change the IPA loading appreciably.)

Bypassing

of

the

PA

screen and filaments

is

accomplished

by

using a number

of

high voltage ceramic capacitors

with

lead lengths kept

as

short

as

possible.

In some transmitters, especially at the higher operating frequencies, there may

be

a capacitor connected between grid and cathode

of

the P.A. This capacitor

is

usually

25

pF

or

50 pF. The purpose

of

adding this

component

is

to

improve the overall performance

of

the

power

amplifier.

4.2 IPA

The intermediate power

amplifier

employs

4CX300A

tetrode in a

common

cathode

circuit.

The plate

circuit

is

common

with

the

PA

grid

as

previously

explained.

Screen bypassing

is

effected

with

the

built-in

capacitance

of

the

4CX300A

air system socket. The IPA cathode

is

bypassed

with

four

ceramic

button

capacitors.

The grid

circuit

is

inductively

tuned and sealed at the Gates

factory.

Since

the

circuit

is

several megahertz

wide

and

will

not

require field adjustment the

variable inductors are accessible

only

with

the

bottom

IPA cover

off.

4-1

Neutralizi1tion

has

been added to the IPA

stage.

A small stud

protruding

from

a ceramic insulator adjacent to the anode

of

the

tube provides the degenerative

feedback pickup. The RF

pickup

is

then returned

to

the grid

input

circuit

to

. stabilize the tube's operation.

After

factory

setling,

it

will

not

require

further

adjustment changes.

4.3

EXCITER

4.4

The FM

exciter

is

described in detail in the

Exciter

section

of

this

instruction

book.

POWER SUPPLY

Only

one high voltage power supply

is

used

in the FM-1OH3. The basic

configuration

of

the supply

is

a three phase

full

wave bridge.

It

supplies 6.6

kV

for

the PA plate, 2.5

kV

for

the IPA plate, 1000

Volt

for

the

PA

screen grid and

280

Volt

for

the IPA screen grid.

The reduced voltages are obtained

from

resistor dividers

which

are connected

to

the center tap

of

the transformer.

The

PA

screen grid voltage

is

variable between

600

Volt

and 1000

Volt

and 'is

controlled

by

the Raise/Lower switch. Series

limiting

resistor, R47 prevents

the PA screen grid

from

over-dissipating in

case

the PA

has

a

loss

of

plate

voltage.

The 0

to

280

Volt

variable supply

for

the I

PA

screen voltage

is

controlled

by

R-26.

Silicon rectitiers

for

this

supply consists

of

three doublers,

each

containing a

number

of

diodes in series

with

proper resistors and capacitors across the

diodes. The diodes are

mounted

in copper heat sinks.

The

PA

bias supply

is

a single

phase

full

wave bridge

circuit

using silicon

rectifiers. Grid bias between 125 and

225

Volts

is

supplied to the PA

control

grid. The bleeder resistor across the

supply;

R-41,

will

also provide'additional

bias voltage

if

the PA grid

current

due

to

RF drive

causes

grid

current

to

flow

above

40

mA

with

160

Volts

fixed bias. R-39

is

the bias adjust

control.

4.5

CONTROL

CIRCUITS

4-2

The

control

circuits

of

the

FM-10H3

consist

of

the

following:

K1 - Primary

Contactor

-Applies voltage

to

the blower,

PA bias supply, and the IPA filaments.

K2 -Plate

Contactor

-Applies

primary

voltage

to

the plate

transformer.

(K2

is

energized after

K3

closes.)

K3 -Step/Start Contactor -It closes and then K2

is

energized,

shorting

out

the contacts

of

K3 and the 1 ohm resistors.

Step/Starting

of

the high voltage supply

is

accomplished

by

K3

closing

first

and applying voltage

to

the transformer

~rimary

through

1 ohm resistors, R22, R23, and R24.

o

-....J

o

Harris FM-10H3 User manual

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