Massive Audio DB8000 Manuel d'utilisateur télécharger pdf (Page 63)

fence charger is shown in Fig. 1.

Any good

power

transistor can

be used

in this circuit.

Some

obvious choices are:

2N255, 2N301,

2N618,

or 2N2869. The

base

resistor should

adjusted

obtain a pulse

rate of about

50 pulses per minute. For the range of

values

shown, you can go from

10 pulses to 100

pulses per minute.

The single

fence wire must be insulated

at each

supporting pole and should be

mounted

low enough to prevent an animal

from crawling

under the wire. Make

use of

TV standoff lead

-in

insulators

to hold

the

wire to the

supporting poles. The wire

should

No.

copper -clad

steel. Build

the unit in a

metal box and arrange

to pro-

tect the circuitry

from the weather.

The two

FILAMENT

TRANSFORMER

TRIAD

F -14%

OOIF

PRIMARY

WIRE

FENCE

1500 TO

10K

SELECT

FOR

PULSE

RATE

NE2H

22K

I/2

Fig. 1. Simple electric

fence shocker.

GROUND

ROO

neon

lamps indicate

when

the unit is oper-

ating. Output

not

lethal, but

will cer-

tainly

keep the cows at home!

A regular

"hotshot"

battery should

last a long time

battery life depends

upon the pulse

rate

chosen; the

slower the rate, the

longer

the

battery

life.

Those readers who prefer to build a fence

charger that operates

from

117 -volt line

should investigate

the

project

published

POPULAR ELECTRONICS, December, 1964, p. 57.

Surplus SCR

-274N

Meters. Where

can I

get some information on how to put

SCR

-274N on 20 meters?

The best article on converting this popu-

lar World

War

II radio set

appeared

in the

April, 1949, issue

of QST. Some

issues may

still be available, or

possibly the

ARRL has

provisions

Xerox pertinent information.

Electric Door Switch. This

may seem like

foolish question, but please recommend

switch that

can use to turn

and

off a

low- voltage (6 -volt) light bulb.

The

prob-

lem is that

do not want the switch to be

visible.

Probably your

best bet is

to bury a sur-

plus

Microswitch

in the

door

jamb.

As the

door closes, the

switch opens. If you're me-

chanically minded, you could probably

as well with

a Grayhill

"Silent- Action"

Se-

ries 4002

miniature push-

button switch.

CB Linear Amplifiers. I have seen

some

ads

for

CB amplifiers

and was wondering

such

an amplifier

is a worthwhile invest-

ment?

I presume the ads you have seen

pertain

linear

amplifiers

for use with your CB

transmitter.

Those

advertisements

are di-

rected toward

people

holding business

band

licenses

and

operating in or around the

same frequencies as your

CB station. Use

a linear amplifier

conjunction

with a

CB station is illegal and can easily

subject

the user to a

fine

and /or loss

of his station

license.

Intermittent Lafayette HE -15. I own

Lafayette

HE -15A

CB transceiver, and up

to a few weeks ago,

it was

doing a

fine job.

Now the receiver is cutting out and

find

necessary to

flip

the transmit

switch off

and on to restore

reception. What's

the

trouble?

About 90% of the time -especially with

these

older

CB units -your most

likely

source of trouble

is in aging tubes. Run

them through a good

tube checker. If the

tubes are okay, substitute a new

coupling

capacitor (0.01µF) between the 12AX7

and

a 6V6GT output tube. Also suspect are

the 22 -pF

and

100 -pF coupling

capacitors

between

the r.f. amplifier (receiver) and

mixer (6U8A /6EA8). Last, but certainly

not

least,

clean

all

switch

contacts with a

good

TV tuner

contact cleaner.

Ham QRM on

Hi -Fi.

1 recently built

-from

a kit -a popular all

-transistor

50- watt

-per-

channel stereo amplifier.

My son is a

ham,

and when he

15 meters, the hi -fi picks

up everything he says.

There must be

some

cure

for

this

nonsense.

Evidently

your hi -fi setup is not bothered

when your

son is operating on some of the

other

ham bands.

This may

a tip -off. I

would first try the simple

expedient of bridg-

ing each speaker

output

connection with

a 0.001 -µF capacitor

-not

enough capacity

to affect your audio

quality,

but enough

bypass some of the

r.f. signal pickup. If

this does not work, try

shielding your speak-

er lines. It will probably also be worthwhile

bypass

the

r.f. out of your a.c.

input

line

to the

hi -fi

amplifier,

which can be

done

by connecting

two

good - quality 0.01 -µF

ceramic capacitors together in series across

the

117 -volt a.c. line.

Tie the center

connec-

tion of the two capacitors

a good

chassis

ground.

Also,

install a similar

filter

at the

ham

rig.

February, 1967

1 2 ... 58 59 60 61 62 63 64 65 66 67 68 ... 115 116

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Massive Audio DB8000 Manuel d'utilisateur Page 63

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