Ameco PT Instructions Manual

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AMECO

PREAMPLIFIER

MODEL

PT

The

AMEC0

Model

PT

Preamplifier

is a unit

that

may

be

added

to

most

existing

trans-

ceivers

in the

frequency

range

ot

l.B

to

54

MHzf

improving

the

gain,

noise

ftgure,

spurious

signal

and

image

rejection

of

the

receiver

section.

This

All-New

pf

ImgCO

Preamplifier

has

been designed

-oecifically

for use

with

a transceiver.

The

sophis-

ticated

control

circuitry

incorpoi '-t

permits

the

PT

to be

added

to

virtually

any

transceiver

without

modiflcation.

Ttre

fundamental

requirement

is

that

the

transceiver

have

control

circuitry

built

in

for

use

with

a

!'1near

ampl

if ier.

This

I

inear

ampl if ier

control

circuitry

is used

to bypass

the

preamplifier

during

transmit

mode

or

to control

the

I

inear

ampl

ifier dlrect!y.

When

the

transceiver

I

inear

ampl

ifier control

ci

rcuitry

actuates

the

relay

in

the PT,

additional

contacts

in ifr.-pf

-"ontiol

the

linear

so that loss

of linear

amplifier

facility

does

not

result.

The

PT

consists

of a

tuned RF

amplifier,

covering

all

the

amateur

bands

from

150

throuqh

5

meterc

sndi in

oiiili,-::,,

lll

..i:.

l;.ig,:

,Ioadcasts,

as

wel i

as

otlrgr

services

within

this

frequency

range.

The

Mo"del

PT

employs

a

low

noise

frame grid

tdbei

pro-

viding

a noise

figure

of 1.5

to'3.5

db,

over

the

frequency

range

of i.B

to

S4'nnz.

The

PT

Preampl

if

ier

wi

ll be

found

especial ly

ef

fective

wiir,

tr,or"

transceivers

em-

ploying

the Pl

output

network

of the

transmitter

section

as

the

receiver

RF

stage

input.

Most

transceivers

of

this

type

begin

to

suffer

a

noticeable

decrease

in

sensi-

tivity

on

l5

meters

and

especiatly

on 10. The

PT

will

be

most

beneficial

on

these

bands

and the inclusion

of 6

meters

makes

it

r.rsable

with

those

second

receivers

having

a 6-meter

range

or with

the

newer 6-meter

single-sideblna

tnansceivers.

ln addition,

the

output

of

the frame grid

RF

amplifier

seition

feeds

an

isolation

net-

work

with

two

outputs.

One

output

is used

to

feed

the

transceiver

input

when

re-

ceiving,

while

a

second

output

is

used

to feed

a

second

receiver,

which

may be

of the

general

coverage

or

amateur-band-only

type. The

built.-in

relay

of

the

pT

also

includes

a

set

of

contacts

with

three

terminals

brought

out

to

tfie

reai

of

the

cabinet

so that

either

normally-open

or

normally-closed

receiver

mutinglmay

ne

employea

in

the

sec-

ond

receiver,

whenever

the

transceiver

transmits.

The

PT

is designed

specifical

ly

for

I

I7-vol

t 60-cycle

operation.

The

input

and

output

impedances

are

nominally

50

ohms

to

match

most

popular

types

of

amateur

installations.

The

input

and

output

impedances

of the

pT

are

not

critical

and'

therefore

no

adjustments

or modifications

are necessary

with

other

impedances.

The

AMECO

PT

is

truly

a

great

step

forward

in

increasing

the flexibility

of a trans-

ggiver

equipped

amateur

station.

The

use

ofra

second

reieiver

with

its

extremely

Ax-rble

operating

characteristics

will be greatly

appreciated

by

the

contest,

DX,

?y-Brffiious.operator,.both

with

cw

and

single

sideband.

once

the

operator

has

A DIVISION

OF

AEFTOTRON,

INC

RALEIGH,

N.C

INSTRUCTIONS

ustomed

to

a typical

setup using

a

transceiver,

together

with

a

pr

and

a

$v"r,

he

will

wonder

how

he

ever

got

along

wiihout

it.

INSTALLAT

ION

To install

the Model

PT,

it is necessary that

observed.

the following

steps

be carefully

DO

NOT PLUG

THE PT

INTO

THE

AC OUTLET UNTIL INSTRUCTED TO DO SO IN STEP

4.

1.

Remove the

power plug

of the transceiver

power

supply

from

the

wall

socket.

and

plug

it

into

the

AC outlet

(marked

TRANSCEIVER)

on

the

rear

of the PT. FAILURE

TO USE THIS OUTLET

AS

DIRECTED

CAN CAUSE

DAMAGE TO THE

AUXILIARY

RECEIVER. SEE

PARAGRAPH

4.

lf

an electric

clock

is

used in

the station,

it may

be

plugged

into

the

clock outlet.

(rHe

cuocr oUTLET ls tilRED

BEFoRE

THE swlTcH,

s0 THAT lT

1s

ALWAYS

ENERGIZED.)

An additional outlet also is

provided

for the second receiver.

An outlet

marked

SPARE may

be used for

a

rotator; however, under no circumstances

should

a

linear amplifier

be

powered

through

the PT. THE LINEAR AMPLIFIER

SHOULD

BE

PLUGGED

DIRECTLY INTO

THE WALL

OUTLET

BECAUSE

OF

THE HIGH CURRENT

DRAIN.

2.

Remove

the

coaxial

antenna

line from the transceiver and connect it to the

jack

marked

ANTENNA

on

the rear of

the

PT.

The

coaxial cable comlng out

of

the rear

of the

PT, terminating

in a

coaxial connector, should then

be

connected to the

transceiver

antenna

jack.

ln

those

installations

employing a

Iinear amplifier

and

the transceiver,

the PT

is inserted

between the linear amplifier

and the

transceiver

(llOf

AETWEEN THE

AI+TENNA

AND THE

LINEAR

AMPLIFTER)

Another cable coming out of the rear of the PT

is

terminated in an RCA-type

phono

connector.

This

should

be

plugged

into

the

linear

amplifier

control

circuItry of

the

transceiver

and,

in turn, the cable normally

coming

from the

linear

to

the

transceiver

should

then

be

plugged

into the

jack

marked

LINEAR

KEY

on

the rear of

the

PT

(in

those.installations employing

a

linear).

ln

some

transceivers

(such

as

Swan), a set of terminals on the rear

of the

chassis

is connected to relay

con-

tacts.

(Refer

to the transceiver

lnstruction

Manual.)

Remove the RCA-type

phono

connector from

the control

cable

(2-conductor

zip

cord)

coming out of the rear

of the

PT, connect the leads

to the normally-open

(during

standby) contacts, as

referenced in the transceiver lnstruction

Manual.

Some

transceivers may require

modification for external

Iinear amplifier control. The

PT is designed

to work

with the control circuitry employed by most

popular

linear

amplifiers,

that

is,

the linear is controlled

by

contacts normally

open, when

the transceiver is

in

a

standby

position.

Some of the more

popular

amplifiers,

employing

this control

circuitry,

are

the

Henry 2K

series,

Collins

30L1,

Hammarlund

HXL-I,

and

so

forth.

At

this

point,

the

PT unit

may

now be

plugged

into

the AC

outlet.

The

switch on

the front

panel

will control not

only

the

power

to

the PT, but

also all items

plugged

into the rear outlets.

This

provides

for

simplification

of station opera-

tion and

insures that the relay control circultry will be

energized

whenever the

transceiver is

in use. FAILURE

T0

D0

THIS

WILL

CAUSE THE TRANSMITTEB,

P0WER

T0

BE

FED T0

THE

SEC0ND

RECEIVER, WHICH MIGHT

CAUSE EqUIPMENT

DAMAGE. A

resistor/fuse,

located

on the

underside

of the chassis

of the PT,

is

also incorporated to

pro-

tect the second

receiver against

such

failureg however,

the

proper

use

of

the

PT will

minimize

risk

of

damage.

3.

4.

5.

6.

7.

8.

INSTALLATION

OF A

SECOND

RECETVER

To connect

a second

receiver, it

is

necessary to run

a coaxial line

from

the AUX

RCVR auto

radio-type

jack,

on

the rear of

the PT,

to the receiver.

An

auto

audio-

type

plug

is

supplied

with the PT,

and

a coaxial

cable of the

RG58/U

type should

be i nstal

led as

fol

lows:

l.

Remove

outer

vinyl covering for

1-7/8

inches.

2,

Strip

braid and

inner

insulation

off center conductor

7 /8

i nch.

3.

Push

braid back to form a

bead

all around.

4.

lnsert

center

conductor

through

ufitil

braid

is

aga i

nst end of

pl

ug.

Bend center conductor to

hold

plug

in

place.

Roll

braid

between

fingers to

roll it over the end

of the

plug

for

about

l/15 inch.

Solder

the braid to the four tabs

of

the

plug.

Solder

the

center

conductor

to the

and

cut

off

excess wi

re.

After installation

of the above, the

PT

will feed

the

second

receiver

as well as the

transceiver.

This will make it

possible

to receive

and

transmit

on separate

frequen-

cies when

using the

PT

or

to

scout

the band without disturbing

the

setting

of the

tuning

dial of the

transceiver. lt

also

will

be possible

to

use

general

coverage

receivers

without

having

to

disconnect

the

antenna

from

the

transceiver

installation

and by

means of the

proper

frequency

selection of the

PT, all

band

reception may

be

had.

The

rear of the PT contains three

terminals

(designated

AUX

CONTACTS) for

muting

the

second

receiver.

This

is highly desirable

when transmitting

so that

noise

and slgnals

do not ride through

on

the transmitter

audio.

Under

certain

conditions, feedback

also might

develop,

particularly

with

certain

relative

frequency

settings

between the

transceiver and

the

second

receiver. Before

connecting

the

muting

terminals, it will

be necessary

to

determine

from

the receiver

lnstruction

Manual

if

normally-open or

normally-closed contacts

are required for muting. ln

those receivers,

muting against

ground,

the

terminal

marked COM

should

be connected

to

ground

or chassis of the re-

ceiver.

ln

those

receivers requiring normally-closed

contacts

for

reception, the

terminal

marked

NC

should

be

connected to the muting

Iead.

Those

receivers requiring

normally-open contacts

for

reception, will require

that

the leads

be

connected to

COM

and

N0

terminals.

Most

receivers, however, use

normally-closed

contacts for

re-

ceiving, which open

during

transmit.

After

wiring in

the muting contacts

to

the

second receiver, each time the

transceiver transmitter

section is actuated, the

second receiver

should

si

lence.

lf

it

is desirable

to use VOX operation with the second

receiver,

it

is

necessary

to

observe certain

precautions

so

that the output of this

second

receiver

will not trip

the VOX circuitry.

Although it is

possible

to

modify

the

transceiver, so as to

feed

audio from the second

receiver in for anti-trip

purposes,

this

is not normally

rec-

ommended

unless the

person

performing

the task has a

very thorough

knowledge

of

the

circuitry and

can

perform

these operations.

For

split frequency operation,

it usually

is best

to

use a

footswitch

or other

such control circuitry with the

transceiver

in

the

V6X,

PTT or

manual modes of

operation.

lf, however,

VOX is desired,

it

is

best to

experiment with

the

placement

of the

microphone with

respect to the speaker

of

the

second

receiver,

so

as to attenuate the audio

path

between

the two as

much as

possi-

ble.

Keeping the

second receiver

volume at a

modest-to-low

level

also will

be

very

helpful

and the

use of a

cardioid-type microphone will further improve the situation.

TRANSCE

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LINEAR

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T0 MODEL Pr

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AC OUTLET

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INSTALLATION

DIAGRAM

TRAilSCEIVER

XODE

,

TRANSMIT

TRANSM IT

RECEIVE

PF:EAIIP

P'TEATP

swrTcH

PT'S

ITION

':UNCTION

DIAGRAM

4

CONTROL

RF

INPUT RELAY

z^r

(e) (a)

Yv

TRANSCEIVER

AUXILIARY

RECEIVER

AIITENNA

RECE t VE

SWITC

H ING

OPE RATION

With

the

P0WER switch

in the

on

(up)

position

and

sition,

the transceiver

should

work

in the

normal

the PREAMP

position,

the

pre-ampl

ifier

section

of

the receiving

system

and,

therefore,

since it

as

fol lows:

the

PREAMP

swi

tch i n

the OUT

po-

fashlon.

With the PREAMP

switch in

the

PT

then

will increase

the

gain

is in

operation,

it

should be

used

l.

Turn

the

MHz switch

to a

position

that includes

the desired

frequency.

For

ex-

ample, the

2O-meter amateur band

is'14

to 14.35 MHz. This

is between

the l0

and

23,

therefore

the

switch

must

be

at the

line

between

l0

and

23.

2.

When a signal

is

received,

peak

it by

"alrrting

the TUNING

control for

maximum

swing

on the

receiver S meter or maximum

volume if

no meter

is used. ln

tuning

over a

band, the

tuning

knob

of the PT

should be adjusted

fairly

frequently.

For

example,

at

AMHz, it may

have

to be

adjusted every

50

kHz. At

50

MHz,

it may

have

to

be adjusted

every

200

kHz.

l.

When

the

PREAMP switch

is left in the

OUT

position,

the unit is in

standby con-

dition with

power

applied

and its

frame

grid

tube warmed

up. lnstantaneous

pre-amplification

is available when

the

switch is

placed

in the PREAMP

position.

4. Because the PT adds considerable

amplification

(approximately

20

db)

to the re-

ceiver section

of the transceiver,

which may

often

have

sufficient

gain, partic-

ularly on the

lower frequency

bands,

overloading

resulting

in

cross

modulation

or

desensitization, or both, may

occur. For

this reason,

a manual

GAIN control

is

in-

cluded on the

front

panel.

Normally,

this control

should

be

turned fully

clock-

wise; however,

under

strong Iocal

signal conditions;

it

may often be

found de-

sirable to reduce this control

to a

point

where

the

local

signals

tune considera-

bly

sharper and,

therefore,

occupy less

space

on the

band. Although

this

will

re-

duce

the

sensitivity,

it will be

very often found, particularly

when desired

signals

are strong, that reduction

will

provide

an

over-all

and more

usable

sig-

nal

than when

the

pre-amplifier

was not

in the circuit.

This

is

particularly

true

in

those transceivers having

considerable

front-end gain

without

provisions

for

separate RF

gain

and lF

gain

controls.

When

switching

the

tuning control

,

or

under

certa i n cond

i

ticularly with the

PT in

and out

of the

circuit

both,

at i ncorrect

sett

i

ngs

,

t ions, an appreciable

s

i

gnal

GA

I

N

control at max imum. Th

i s

with

the band

switch or the

i

t wi I

I be not

iced

that,

will

still come

through,

par-

is normal

.

Some'transceivers, having

especially

good

AVC

action,

will

tend to make

tuning

the

PT

difficult,

particularly

on strong signals. This

can be

overcome by watching the

S meter

very carefully

while

peaking

the

PT,

peaking

up

on

a

weak signal,

or

peaking

up

on the

background noise in

the absence

of a

signal.

The

true

worth

of the

PT will

be more

fully realized

under

extremely

poor

band

conditions

whenever

signals

are

very weak.

NOTE.

lf the receiver

sensitivity

appears to be

very

Iow,

regardless

of

the

setting of

the

band

switch and

the tuning

control,

the fuse/resistor

in

the

antenna

circuitry

should

be

checked.

(ffre

fuse/resistor

in

the

antenna circuitry is

located

on the

underside

of the

chassis,

at the

right

front.)

t.

ALIGNMENT

PROCEDURE

The

preamplifjer

in the

PT

has no adjustments.

All

tuning is done by

the variable

con-

denser.

Cl

'is

a

reactance cancelling

capacitor

which'is

used

to reduce

the SWR

to less

than

l.l:l

The

adjustment

procedure

is

as follows:

l.

Connect

a transmitter

to

a

standing

wave bridge.

2.

Connect the

PT Pl to

the bridge.

3.

Connect

a

good

50 ohm dummy load

(such

as. Bird,

Sierra,

etc.)

to the PT

Jl.

4. Short PT PZ during this whole test,

the

power

MUST

be

on the

PT.

5. Tune up

the transmitter

on 52 MHz

if

ava'ilable,

otherwise

on the

h'ighest frequency on

the

transmitter.

Use

35

watts

minimum.

6. Switch

to

read reflected

power.

7. Adjust

C1

for

a

mjnimum

reading.

Do not disturb Cl except

in the complete

procedure

above.

REPLACEMENT

OF

THE FUSE/RES|STOR

To replace fuse/resistor

R10,

use only Allen Bradley

or

0hmite carbon

composit'ion,

l/1O-watt

size.

Do not use l/4-watt

or

deposited

carbon resistors

as they will not

break

quickly

enough.

Unsolder

the

remains of the

broken

res'istor

from

the

lug and

the spring

wire.

Solder one

end of

the

rep'lacement

resistor

to the

terminal

lug. Hook

the other end

oVei

ttre spring

wire and

pu11

the

lead until

the

spring is

-dEiieeted

about 1/16 inch.

hlh'ile

holding this

position,

solder

the

resistop

lead

to the spring wire.

Before

unsoldering

diodes

CR2

and

CR3,

check with an

ohmmeter.

Diodes are

good

if

the reading

is

.l00

ohms or less

jn

e'ither

polarity.

If

the

reading

is

high

in one

pol

ari

ty,

repl ace the two

d'iodes

wi

th type

'l

N281

on1y.

PARTS LIST

Most

components

used

in th'is

unit

are

available as over

the

counter items at any

radio

parts

supply store. Listed

below, are

specia'l items

that

are obtainable from AEROTR0N

on1y.

ITEM

DESCRIPTION

PART

NO.

R10

CR2

CR3

K1

LI

L2

L3

L4

S2

TI

T2

100 ohm,

t70%,

7/10 watt,

comp.

Diode, I N28l

D'iode

,

I

N28l

Re"lay, 4PDT, I l0 VDC coi I

Cojl,

l.B-4 MHz

Coil,

4-.l0 MHz

Co'il,

l0-23 MHz

Coi1,

23-54 lt1z

Swjtch,

rotary, 2

po1e,

4

posjtjon

Transformgr, Toroid

Transformer,

Power

47a5

loo3

oor

4804

0000 006

4804

0000 006

4507 0000 002

lB20 l615 021

I 820 1 615 022

tB20 t6t5

023

1805 I 615 024

5ll0

0000 017

5649 I 601 A25

56.1

0 0000 0t 9

2.

3.

4.

AUX CONTACTS

TRANSCEIVE

R

ANTENNA

Pl r

AUX RCVR

J2

LINEAR

KEY

J3

I

>-t-

'_L

=

TRANSCEIVER

LINEAR KEY

P?

N0TESI

I. UNLESS

OTHERIIISE SPECIFIED CAPACITOR

VALUES

ARE

IN

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.

RES1STOR

RESISToR

VALUES

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DSI

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PT

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A DIVISION OF

AEROTRON, INC.

P.

O.

BOX 6s27

BALEIGH.

NORTH

CAFIOLINA 27608

4201 r6t5 701

-

9/69

PRINTED

IN

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Ameco PT Instructions Manual

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