Metra Electronics DAT Combo Bedienungsanleitung PDF herunterladen (Seite 28)

Ask

Me

Another

VFO or Crystal?

How can 1 install

a crystal in my

30

to 50-

MHz band

FM

receiver

for receiving

on 39.46

MHz?

-A reader,

Someplace, USA

The first

diagram

is the

circuit of the oscil-

lator stage of your

set,

according

to the

schematic you sent. The

second

diagram

is the

modified circuit. Use the same oscillator coil

tuned by a trimmer capacitor. Disconnect the

oscillator section of the main tuning

capacitor.

You

still

use the tuning dial to tune the RF

amplifier and mixer to 39.46 MHz. For that

frequency,

use a 28.76 MHz crystal.

TO

MIXER

a

MM

MMF

.IMF

12ÁT7

tTO MIXER

a7

MMF

T

L3

It's

a

Boo -Boo!

When

n

atcliing TV commercials 1

have

noticed that a commercial

will

come on

for a

second

or

two and then there is

some kind

of

a

switch. The commercial

comes back

on but at

the beginning

instead of at the point

where

it

was

interrupted.

Do TV

stations or networks

run

two films

of the

same program

at the

same

time, with

one as

back-up?

-W. A.

W.,

Huntington,

West

Va.

Checking

with a major

TV station in New

York City,

it

was learned

that no

back -up film is

used. In case

of

failure, the operator

probably

winds the film

back up on the

reel and reruns

it. Thus,

you

will see it from

the beginning.

Even though

film problems

do sometimes

arise,

station

and

network executives

often

let

opera-

tors

know

that "it

will not

happen

here."

...

but

it does- sometimes.

30

OCR for

ZIP

What

is OCR and what is

it used

for?

-N. K.,

Philadelphia,

Penna.

One meaning

of OCR is

optical character

recognition,

a technique for reading printing

and

written

matter electronically. In one

sys-

tem,

each character is looked at quickly

by

a

flying -spot scanner,

a

kind of TV camera.

What

the scanner "sees" is sent

in

the

form

of

electrical

signals

to

logic

circuits

which

identify

the

character and send

a

digital

sig-

nal to a computer. For example,

the logic

circuitry can

determine the

difference

be-

tween

a

handwritten lower

-case

E

and a

lower

-case L. Both look alike

but

one is

taller.

OCR systems are

used

to

read

ac-

counting forms and

other documents as

well

as the

ZIP code on letters.

Ceylon

to a "T"

What

make and model shortwave set

might be

capable of

receiving Radio

Ceylon

on 11,800

kHz here in California?

-G.

G.,

Davis, Calif.

Almost any

sensitive superhet

shortwave re-

ceiver that can

be tuned to that

frequency

should

be able to pickup

the signal

when it is

bounced your

way. However, the set

should be

equipped

with

a good

outdoor antenna.

B -plus and Filament

Power

Is

it possible

to

build u AC

-power supply

furnishing

22.5 to 30 volts DC and

6.3

volts

for

a

radio using a 3A U6

tube?

-T. L., Springfield,

Ohio

You can

use

the circuit

shown.

The

trans-

former furnishes

3.15 and

6.3

volts AC. Plate

voltage is

obtained

from the AC line through a

voltage divider composed of

four No. 327

pilot

lamps.

According to the

RCA Receiving Tube

Manual, a 3AU6 tube

requires

3.15

volts,

not

6.3

volts,

for

its filament, as

does a 6AU6.

RADIO-TV EXPERIMENTER

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