DZ HT-7 Скачать руководство пользователя страница 28 | Manualshive

Страница: 28 / 44

DZ HT-7 Скачать руководство пользователя страница 28

Page 28

THEORY OF OPERATION

Transmitter

operation

When

the

PTT

switch,

S1,

is

in

the

transmit

position,

supply

power

is

routed

to

the

transmit

‐

ter

circuits

and

not

to

the

re

‐

ceiver

circuits

(HT

‐

7

‐

2

board,

sheet

2

of

schematics;

11.1V

‐

>

TXV).

Built

‐

in

electret

mic

M1

receives

power

from

the

5V

regulator

U3

and

is

then

fed

to

the

main

board

where

it

is

routed

to

the

exter

‐

nal

microphone

input

via

a

short

‐

ing

connector

so

that

if

no

ex

‐

ternal

microphone

is

plugged

in,

the

internal

electret

microphone

remains

connected

to

the

ampli

‐

fier.

The

microphone

preamp,

U1,

is

an

audio

amplifier

whose

gain

is

controlled

via

RV2.

The

input

impedance

is

set

to

50K

ohms

(the

parallel

combination

of

R3

and

R4,

which

also

set

the

bias

on

the

positive

op

‐

amp

input

to

one

‐

half

of

the

supply.

This

is

nec

‐

essary

since

the

op

‐

amp

operates

with

only

a

single

positive

sup

‐

ply.

Capacitor

C14

keeps

the

DC

gain

at

one,

via

R5,

while

the

AC

gain

can

be

set

between

3

and

in

‐

finity

(1

+

100K/RV2).

The

output

of

U1

is

coupled

via

C4

and

resistor

R6

to

Gilbert

cell

double

balanced

mixer

U2,

which

mixes

the

audio

with

RF

from

the

7.290MHz

local

oscilla

‐

tor

consisting

of

Q1,

Y1

and

re

‐

lated

parts.

The

balance

is

upset

by

pot

RV1,

which

allows

the

car

‐

rier

to

pass

through

the

mixer

along

with

the

double

sideband

signal.

The

output

of

the

mixer

is

fed

to

the

main

board.

On

the

HT

‐

7

‐

2

board,

the

AM

sig

‐

nal

is

fed

into

PTT

switch

S1

at

W9

(Sheet

2

of

the

schematic

for

the

HT

‐

7

‐

2).

When

the

PTT

switch

is

pushed,

the

signal

is

routed

to

FIN

(Filter

Input)

on

Sheet

1.

Q1

amplifies

the

signal

to

over

‐

come

the

loss

of

the

following

crystal

filter.

The

filter

has

an

1800

ohm

input

impedance,

so

this

transistor

also

serves

to

match

this

impedance.

The

crystal

fil

‐

ter

is

a

6kHz

wide

crystal

lat

‐

tice

filter,

which

rejects

all

harmonics

and

unwanted

mixing

products

from

the

AM

signal.

The

output

of

the

filter,

FOUT,

is

fed

into

variable

gain

RF

am

‐

plifier

U3,

an

Analog

Devices

AD603.

The

gain

of

this

RF

ampli

‐

fier

can

be

set

from

–10

to

+40dB

by

changing

the

DC

voltage

on

pin

1

to

between

6.1V

and

7.2V.

This

is

done

by

pot

RV2.

In

transmit

mode,

diode

D5

and

resistor

R38

change

the

voltage

on

pin

2

to

8V,

which

keeps

the

gain

of

the

AD603

at

minimum,

since

no

addi

‐

tional

gain

is

needed

in

the

transmit

chain.

Refer

to

the

schematics

on

pages

35

‐

38.

«
...
26
27
28
29
30
...
»

Содержание HT-7

Страница 1: ...Page DZKit ASSEMBLY MANUAL HT 7 40M AM HANDIE TALKIE Price 10 00 DZ CompanY LOVELAND COLORADO...

Страница 2: ...stance phone call on any problem you may encounter in the assembly or use of your DZKit product Just drop us a line email us give us a call or visit our website and click on Support That will give you...

Страница 3: ...eserved 3 24 09 HT 7 TABLE OF CONTENTS Introduction 4 Available Accessories 5 General Assembly Safety Notes 6 Parts List 12 Step by step Assembly 14 Chassis Integration 19 Adjustments and Tests 22 Fin...

Страница 4: ...enjoy the fun of those old style QSOs which were typically long winded since VOX was not used and switching over from transmit to receive took longer Now you can enjoy the fun of AM without spending...

Страница 5: ...A 2 tuner HTA 1 Battery Pack Includes built in overcharge overdischarge overdrain short circuit and reversed polarity protection Weight 10 4 oz 370g Dimensions 2 6 66mm x 2 1 53mm x 1 7 43mm Must be r...

Страница 6: ...g give us a call or email us and we will rush a replacement to you 4 Most electronic kits that are returned for service have poor soldering jobs Please take a moment to familiarize yourself with prope...

Страница 7: ...containing pin 1 When you hold an IC with the notch pointing up or the beveled side to your left pin 1 is in the upper left corner The silkscreened outlines on the board all have notches and pin 1 als...

Страница 8: ...ong will only delay that moment Before you start set up a ventilated static free work area with enough room to build the kit Prepare parts bins and get the tools you will need needle nose pliers wire...

Страница 9: ...d cause damage to workbenches and carpets We recommend you use one with an auto matic shutoff in case you forget to turn it off when you are done 5 Do not work on electronic projects when you are tire...

Страница 10: ...ouching the iron to both the component lead and the pad at the same time Solder bridge Solder that stretches from one trace or pad to another creates a short cir cuit Solution Hold the board upside do...

Страница 11: ...ic items by touching a grounded object such as the corner of a wall In a dry environment simply standing up after sitting in a non grounded chair can also charge you with electricity If you stand up t...

Страница 12: ...double throw momentary switch 1 11 T1 T36 1 1 12 T2 T3 FT37 43 2 13 J4 2 pin right angle MTA connector 1 14 U2 LM380 audio amplifier IC 1 15 Y1 Y7 7 287MHz HC49 U crystal 7 16 Screw 4 40 x 1 4 PH Phi...

Страница 13: ...1 12 Screw 6 32 x 1 4 FH Phillips M S Black 4 13 Screw 6 32 x 3 8 PH Phillips M S 2 14 Nut 6 32 KEPS 5 15 Nut 6 32 hex 1 16 6 Solder lug 1 17 6 Nylon washer 2 18 Angle bracket 2 19 Knob 1 20 2 pin fe...

Страница 14: ...both leads and clip excess lead length Load and solder RV2 the 10K trimpot Clip excess lead length Load and solder T1 the 6 pin DIP transformer The pin marked with a dot must go into the square pad L...

Страница 15: ...Page 15 Pictorial 1 Component placement on HT 7 2 Board...

Страница 16: ...sistor lies flat against the board Insert all 12 of the red magnet wire into an FT37 43 toroid core leaving 2 out side Wrap the wire nine times around the core pull ing tightly on each turn Re member...

Страница 17: ...w heatsink 4 40 x 3 8 spacer Transistor ThermalsilTM insulator apply sticky side to heatsink and remove material covering the hole Pictorial 2 Q3 preparation Thermalsil is a trademark of Aavid Thermal...

Страница 18: ...marked T3 1 and T3 2 and the green secondary leads go into holes marked T3 3 and T3 4 The center of the toroid should be placed directly over the center hole Prepare RF power transistor Q3 as shown i...

Страница 19: ...the jack and save them Sandwich the speaker between the electret mic board and the preamp mixer board HT 7 1 using two 6 32 x 3 8 screws two 6 Nylon washers between the speaker and the HT 7 1 board o...

Страница 20: ...wire that is attached to the crystal to the braid then cut the bare wire near the point where it attaches to the crystal Slide the tubing over the braid and ap ply heat until it shrinks over the conne...

Страница 21: ...into the connector on top of the unit using a 5 5mm plug center pin positive One such connector with a lock ring is provided in the kit Set the voltage to 11 1VDC If you have a current limit control s...

Страница 22: ...r is set for exactly 7 290MHz Board Transmit Receive Measurement point Voltage DCV HT 7 2 R T D3 cathode 11 1 HT 7 2 R T Q1 base 3 1 HT 7 2 R T Q1 emitter 2 4 HT 7 2 R T Q1 collector 6 8 HT 7 2 R T U3...

Страница 23: ...the four connectors pointed up Insert the speaker as far as it will go into the opening in the HT 7 2 board with the termi nals facing to the right and the speaker cone facing you Insert the HT 7 2 b...

Страница 24: ...pliers and make very slight turns until the nuts are tight Attach two 6 32 angle brack ets to the top using two 6 32 KEPS nuts Align the side with the non threaded opening with the mounting studs Ex...

Страница 25: ...he lockwashers on the BNC con nector and the washer on the volume control pot are on the inside of the chassis Attach the knob to the volume control shaft aligning the white line on the knob with the...

Страница 26: ...Page 26...

Страница 27: ...inexpensive Lithium Ion charger or you can charge it inside the HT 7 by con necting a power supply set to 12V with a current limit of 4A to the power jack on the top of the HT 7 Internal protection ci...

Страница 28: ...er U2 which mixes the audio with RF from the 7 290MHz local oscilla tor consisting of Q1 Y1 and re lated parts The balance is upset by pot RV1 which allows the car rier to pass through the mixer along...

Страница 29: ...the 4 7 ohm emitter re sistance RFC1 and C33 assure that the top side of T2 is at AC ground T2 has a 9 3 turns ratio which causes an impedance step down to the next stage The 2SC2166 final amplifier h...

Страница 30: ...ss A amplifier of 50 The output low pass filter is a 7 element Elliptical filter with a cutoff frequency of 8MHz This frequency was chosen to get as close to 7 29MHz as possible so as to eliminate har...

Страница 31: ...known as input offset voltage a property of real op amps The inverting input is of ten called the summing junction as the sum of the currents in that node will be zero Since virtually no current flows...

Страница 32: ...from a single supply Again any nonlinear voltages developed across the diodes are not rele vant The two rectified half waves are combined in the next two op amp stages The two out puts of the rectifi...

Страница 33: ...ed gain state Its value is high so as not to affect the gain when the diodes are conducting Recall that an AM signal contains the carrier as well as the audio information Demodulation pro duces a sign...

Страница 34: ...requency 7 290MHz Amplitude modulation Bandwidth 6kHz Output Power approx 2 Watts Transmitter Spurious Output 45dB Transmitter IMD 20dB Receive Sensitivity 1uV Power requirements 10 12VDC 50mA receive...

Страница 35: ...Page 35 SCHEMATICS...

Страница 36: ...Page 36...

Страница 37: ...Page 37...

Страница 38: ...Page 38...

Страница 39: ...pin Reversed electro lytic capacitors can draw exces sive current and they can even smoke Verify all voltages using the chart on page 22 A review of the theory of opera tion may also help you determin...

Страница 40: ...Page 40 COMPONENT LOCATOR...

Страница 41: ...Page 41 NOTES Use this page to keep track of modifications purchase information service or anything you like...

Страница 42: ...Page 42...

Страница 43: ...Page 43...

Страница 44: ...Page 44 DZ COMPANY UNIQUE electronic equipment in kit form LOVELAND COLORADO...

Отзывы:

Нет отзывов