Hal Communications DKB-2010 User manual

HAL DKB-2O1O DUAL MODE KEYBOARD

TECHNICAL MANUAL

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WARRANTY

HAL Communications Corp. warrants that all factory-assembled DKB-2010 Dual

Mode Keyboards shall be free of defects in materials and workmanship under

normal use and service for a period of one year from the date of shipment, and

further warrants that all parts supplied with DKB-2010 kits shall likewise be free of

such defects for the same period.

In fulfillment of this warranty, HAL Communications Corp. will, at its option, repair

or replace at no cost except for transportation expenses any factory-assembled

keyboard (or, in the case of kits, any component) verified to be defective, provided

that written notice of such defect is given during the warranty period.

Please do not return your keyboard or components to the factory until you have

sent a letter of notification and

have received a written return authorization.

This warranty is and shall be in lieu of all other warranties, whether expressed or

implied, and of all other obligations or liabilities on the part of HAL

Communications Corp. resulting from the installation or use of this keyboard.

The foregoing warranty is completely void for all keyboards and keyboard

components which have been damaged, abused, modified, or improperly installed

or operated.

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publication may not be reproduced in any form without the

written permission of the copyright owner.

November, 1978 Printing

November, 2015 Reprint DC7XJ

________

NOTE: Inverted states – usually written for example as "HERE IS" – are shown in blue in this text.

TABLE OF CONTENTS

Specifications ........................................................................... 4

Section I: General Information

1.1 Description ....................................................... 6

1.2 Instrument Identification .................................... 6

1.3 Accessories Furnished ........................................ 7

1.4 Manual Preview ................................................. 7

Section II: Installation

2.1 Initial Inspection ................................................ 8

2.2 Preliminary Checkout .......................................... 8

2.3 CW Transmitter Keying Connections .................... 8

2.4 RTTY Loop Connections ..................................... 10

2.5 Audio Output Connections .................................. 12

Section III: Operating your Keyboard

3.1 Introducing ....................................................... 13

3.2 RTTY Operation ................................................. 13

3.3 Morse Code Operation ....................................... 15

Section IV: Theory of Operation

4.1 Introducing ....................................................... 16

4.2 General Operating Principles ............................... 16

4.3 Circuit Analysis .................................................. 17

4.4 Scanning Keyboard Encoder ............................... 19

4.5 ROM Code Converter ......................................... 20

4.6 Storage Buffer ................................................... 20

4.7 RTTY Control and Decoding Circuit ...................... 21

4.8 Shift Register and Control Circuit ........................ 22

4.9 RTTY Encoder and Loop Interface ....................... 25

4.10 RTTY Timing Chain ........................................... 27

4.11 RTTY Character Counter .................................... 28

4.12 Morse Character Generator ................................ 28

4.13 Morse Output Control ........................................ 31

4.14 Quick Brown Fox and ID Control ........................ 32

4.15 Identifier .......................................................... 33

4.16 Three-Character Sequencer ................................ 34

4.17 Power Supply ................................................... 34

4.18 Character Codes ............................................... 35

Section V: Assembly Instructions ............................................ 40

Section VI: Maintenance .......................................................... 45

Section VII: Parts List .............................................................. 57

Section VIII: Diagrams .............................................................. 60

Extended Memory Option

1. Introduction ..................................................................... A1

2. Installation ...................................................................... A2

3. Operating Instructions ...................................................... A3

4. Theory of Operation ........................................................ A4

Schematic ............................................................................ A5

Key Buffer Timing ................................................................ A6

ILLUSTRATIONS

Figure 2.1: Typical Connection for Cathode Keying ........................................ 9

Figure 2.2: Typical Connection for Grid-Block Keying ..................................... 10

Figure 2.3: Typical Loop Circuit Connection .................................................. 10

Figure 2.4: Connection for Loop Circuit with Negative Lead Grounded ............ 11

Figure 2.4a: Plug Preparation ....................................................................... 11

Figure 2.5: Bridge Polarity Protection Circuit ................................................. 12

Figure 3.1: Location of Controls and Keys ..................................................... 14

Figure 4.1: MM5740 Keyboard Encoder Integrated Circuit .............................. 18

Figure 4.2: Shift Register Waveforms for Transmission of the Letter "F" .......... 24

Figure 4.3: Shift Register Control Signals for Morse Operation ........................ 25

Figure 4.4: Generation of the Letters-Shift Code ........................................... 26

Figure 4.5: Generation of the Figures-Shift Code ........................................... 26

Figure 4.6: Morse Clock and Decoder Waveforms .......................................... 29

Figure 4.7: Production of Dots by the Morse Character Generator .................. 29

Figure 4.8: Production of Dashes by the Morse Character Generator ............... 30

Figure 4.9: Suppression of Dot at End of Character to Produce Intercharacter

Space ....................................................................................... 31

Figure 4.10: Development of Clock Pulses for Automatic Character Sequencers 33

Figure 5.1a: Rear Panel Component Placement

Figure 5.1b: Matching Transformer and Terminal Strip Details

Figure 5.1c: Rear Panel Wiring

Figure 5.1d: Wiring Detail for T301

Figure 5.2: Installation of Power Cord Strain Relief

Figure 5.3a: Top Panel Component Placement

Figure 5.3b: Top Panel Wiring

Figure 5.4: Wiring Harness Placement

Figure 5.5: Assembly of Cabinet End Panels

Figure 5.6: Space Bar mounting detail

Figure 5.7: Integrated Circuit Orientation

Figure 5.8: Mounting the MJE521 Power Transistor

Figure 5.9: Capacitor Placement on Power Supply Board

Figure 5.10: Jumper Placement on Logic Circuit Board

Figure 5.11: Weight-Ratio Jumper Placement

Figure 5.12: Bottom Cover Assembly

Figure 5.13: Assembled DKB-2010 with Bottom Cover Removed

Figure 5.14: Diode Placement in Identifier Matrix ........................................... 44

Figure 6.1: Logic Circuit Board Test Points .................................................... 50

Figure 6.2: Keyswitch Circuit Board Test Points ............................................. 51

Figure 6.3: Power Supply Circuit Board Test Points ....................................... 52

ILLUSTRATIONS (continued)

Figure 8.1: DKB-2010 Block Diagram ........................................................... 61

Figure 8.2: Drawing Conventions ................................................................. 62

Figure 8.3: Keyboard Encoder ..................................................................... 63

Figure 8.4: ROM Code Converter and Buffer Control ...................................... 65

Figure 8.5: RTTY Control and Decoder ......................................................... 67

Figure 8.6: Shift Register Control ................................................................. 69

Figure 8.7: RTTY Encoder and Loop Interface ............................................... 71

Figure 8.8: RTTY Timing Chain .................................................................... 73

Figure 8.9: RTTY Character Counter ............................................................ 75

Figure 8.10: Morse Character Generator ........................................................ 77

Figure 8.11: Morse Output Control ................................................................ 79

Figure 8.12: Quick Brown Fox Generator and ID Control ................................. 81

Figure 8.13: Identifier .................................................................................. 83

Figure 8.14: Three-Character Sequencers ...................................................... 85

Figure 8.15: Power Supply Module ................................................................ 87

Figure 8.16: Power Supply Board Component Layout ..................................... 89

Figure 8.17: Keyboard Circuit Board Component Layout ................................. 90

Figure 8.18: Keytop Positions ....................................................................... 91

Figure 8.19: Main Logic Board Component Layout - IC's ................................. 92

Figure 8.20: Main Logic Board Component Layout - Small Parts ...................... 93

TABLES

Table 3.1: Characters Produced by Bracketed Keys ...................................... 13

Table 4.1: RTTY Timing Chain Output Frequencies ....................................... 27

Table 4.2: ASCII Character Codes Used in the DKB-2010 .............................. 36

Table 4.3: ROM Character Input and Output Code ....................................... 37

Table 4.4: RTTY Baudot Codes ................................................................... 38

Table 4.5: Morse Codes ............................................................................. 39

Table 5.1: Coding Chart for Identifier .......................................................... 41

Table 6.1: Test Points - Logic Circuit Board ................................................. 49

Table 6.2: DKB Logic Board Connector (J305) .............................................. 53

Table 6.3: DKB Keyboard Connector (J306) and DKB Power Supply (J307) .... 54

Table 6.4: DKB-2010 Wire List .................................................................... 55

Table 6.5: Integrated Circuit Pin Numbers for Ground And Power .................. 56

DKB-2010 SPECIFICATIONS

RTTY MODE

Code:

International Teletype, Baudot

Character Format:

1 start bit (space)

5 data bits (mark or space)

1.5 stop bits (mark)

The duration of each bit is one select time,

determined by the transmission rate. The minimum

stop bit length for Baudot code ranges from 1 to

1.46 bits, depending on transmission rate and

application.

Data Sense:

Mark or "1": holding condition, output con-

ducting.

Space or "0": signaling condition, output noncon-

ducting.

Character Transmission Rates:

60 words per minute, 45.45 baud.

Select time: 22 msec.

66 words per minute, 50.0 baud.

Select time: 20 msec.

75 words per minute, 56.9 baud.

Select time: 17.57 msec.

100 words per minute, 73.7 baud.

Select time: 13.47 msec.

Also available on special order:

132 words per minute, 100 baud

Select time: 10 msec.

Transmission Rate Accuracy:

Crystal controlled to within ± .05 % for ambient

temperatures from 50 to 95 °F (10 to 35 °C).

Output Interface:

Isolated loop switching transistor.

Ratings:

Voltage, nonconducting: 250 V DC

Current, conducting: 80 mA DC

Isolation voltage rating:

Either loop connection to chassis and ground 250

V AC or DC.

Output Power Rating: 1 Watt.

RTTY Keyfunctions:

10 numeric (0 through 9)

26 alphabetic (A through Z)

15 punctuation marks:

. , : ; / " - ! " # & $ () '

3 carriage control keys: linefeed

carriage return, and blank

2 shift keys

1 break key

2 manual case-change keys

2 three-character memory keys (CQ and AUX)

(repeating)

Unless otherwise requested, AUX key transmits

"DX" plus a space.

1 identifier key (HERE IS) (repeating)

1 test message key (QBF: "quick brown fox")

(repeating)

1 space bar

Identifier:

Transmits the letters "DE" followed by the pre-

programmed station call sign of up to 12

characters when the HERE IS key is struck.

Message repeats as long as key is held down.

Test Message Generator:

Transmits the message "THE QUICK BROWN FOX

JUMPS OVER THE LAZY DOG'S BACK

Ø123456789" when the QBF key is struck.

Repeats if key is held down.

End-of-Line Warning:

Panel lamp lights and audio tone burst is emitted

if more than 64 printing characters are trans-

mitted without an intervening carriage return.

Character Buffer Memory:

Stores up to three characters if typing speed

exceeds character transmission rate. Panel lamp

warns when memory is full. Optional 64 and 128

character buffers are available.

N-Key Rollover:

New key may be pressed before the preceding

key is released.

Automatic Case Shift:

Numbers may be transmitted without use of the

shift key; case shift codes are transmitted auto-

matically.

DKB-2010 SPECIFICATIONS (continued)

Morse Mode

Code:

International Morse

Data Sense:

Keyed: output conducting

Space: output nonconducting

Character Transmission Rate:

Continuously adjustable from less than 8 to

greater than 60 words per minute.

Character Weight:

Any of six weight ratios from 1:7 to 3:1 may be

chosen. A panel switch permits selection of the

four standard weights: Heavy (5:3), normal

(1:1), light (3:5), and very light (1:7). The switch

wiring may be altered to substitute ratios of 1:3

and 3:1 in place of one or two of the standard

weights.

Note: Character weight is the ratio of dot

duration to the length of the space between

adjacent dots or dashes. For the normal weight

ratio of 1:1, the ratio of dot and dash lengths is

1:3. For other weights, dash duration is equal to

the length of two dots plus the duration of one

space between consecutive dots or dashes.

Output Interface:

Transmitter keying transistor may be used for

either cathode or gridblock keying (but not both

simultaneously).

Transistor ratings:

Cathode keying:

Voltage, nonconducting:

+250 V DC

Current, conducting: 150 mA DC

Grid-block keying:

Voltage, nonconducting:

–150 V DC

Current, conducting: –150 mA DC

Output power rating: 1 Watt

Morse Keyfunctions:

10 numeric (0 through 9)

26 alphabetic (A through Z)

9 punctuation marks:

. , : ; / " - ' ()

5 special character keys:

(SK, AS, AR, KN, BT)

2 shift keys

1 break (tune) key

1 error key (8 dots)

2 three-character memory keys:

(CQ and AUX)

1 identifier key (HERE IS)

1 space bar

All RTTY-only keys produce the Morse error signal.

Sidetone Oscillator:

Internal speaker emits audio tone keyed in

synchronism with output keying transistor.

Volume adjustable by panel control. Pitch

adjustable by internal control.

Identifier:

Performs same function as in RTTY mode.

Character Buffer Memory:

Performs same function as in RTTY mode.

N-Key Rollover:

Performs same function as in RTTY mode.

General:

Size: 13.5" wide, 5" high, 9" deep

(34.3 × 12.7 × 22.9 cm)

Weight: 5 lbs. (2.27 kg.)

Power:

105 - 125 V AC, 47 to 440 Hz, 1/8 amp. (Optional

220 - 250 V AC, 1/16 amp).

Operating Temperature:

50 to 95 °F (10 to 35 °C).

I. GENERAL INFORMATION

1.1 Description

The HAL DKB-2010 is a solid-state, electronic keyboard designed for transmitting both RTTY (Baudot)

and Morse codes. A successor to HAL Communication's popular first-generation keyboards, the DKB-2010

provides many advanced operating features:

1. A three-character buffer memory stores the characters typed for transmission at a constant rate.

Coupled with the n-key rollover capability, it helps iron out variations in typing speed and style.

2. A station identifier, included as standard equipment, automatically transmits the station call sign at the

touch of a key.

3. The four RTTY operating speeds (60, 66, 75, and 100 words per minute) are switch selectable and, to

assure stability, crystal controlled. The Morse speed is continuously variable from 8 to 60 words per

minute.

4. A warning light and tone signal the RTTY operator when line length exceeds 64 characters.

5. A built-in RTTY test generator automatically transmits a standard test message ("THE QUICK BROWN

FOX JUMPS OVER THE LAZY DOG'S BACK Ø123456789") at a single keystroke.

6. The Morse code weight can be set to any of four ratios by a frontpanel switch. Weight is unaffected by

changes in speed.

7. The space bar functions in the Morse mode to simplify interword spacing.

8. Two "memory" keys can be preprogrammed to automatically transmit three-letter combinations. One is

normally used to transmit "CQ", followed by a space. The code for the other (the AUX key) is selected

by the owner at the time of purchase; if not specified it is coded to transmit "DX" followed by a space.

For the RTTY operator, the DKB-2010 provides automatic transmission of the case-shift code when

typing numbers and letters; the shift key is needed only for certain punctuation marks. The loop switching

transistor in the keyboard output stage is completely isolated from chassis and ground so that it may be

connected at any convenient point in the station loop circuit.

For Morse operation, a sidetone oscillator with adjustable pitch and volume simplifies monitoring of the

transmitted code. Five double-character keys (SK, AS, AR, KN, and BT), along with an error key (which

transmits eight dots), provide the special characters needed in Morse work. A tune key overrides the

keyboard output and keys the transmitter on for adjustment. Keying is accomplished by a high-voltage

switching transistor, which may be connected for either cathode or grid-block keying.

The keyboard circuitry is constructed on three G-10 glass-epoxy circuit boards, housed in an attractive

yet rugged two-tone gray cabinet. The circuit boards are interconnected by a factory-prepared wiring

harness to simplify construction and servicing. Output connections are conveniently located on the rear

panel. The internal power supply incorporates active, series-pass regulators to ensure stability.

1.2 Instrument Identification

Your keyboard is identified by a serial number tag on the rear panel. It is suggested that you record it in

the space provided on the title page of this manual. Please refer to the serial number when contacting the

factory for information or service.

1.3 Accessories Furnished

The DKB-2010 is shipped with the following accessories:

2 6-contact plugs

2 3-contact plugs

18 female connector pins

1 phono plug

2 lengths, 2 conductor shielded cable

1 operating and service manual

1.4 Manual Preview

This manual is provided to help you get the most from your keyboard, whether you have selected the

factory-wired or the kit model. In the following sections, you will find instructions for installing and operating

the DKB-2010. Please read them carefully before attempting to use your keyboard.

Section 4 provides a full description of the keyboard circuitry. Step-by-step instructions for constructing

the keyboard kit will be found in Section 5; testing and maintenance are covered in Section 6. Parts lists and

a complete set of schematic diagrams are bound at the rear of the manual in Sections 7 and 8 for ease of

reference.

FOR KIT-BUILDING INSTRUCTIONS, TURN TO PAGE 5-1.

II. INSTALLATION

2.1 Initial Inspection

When you unpack your DKB-2010 keyboard, examine it carefully. If evidence of shipping damage is

found, contact the carrier immediately. Before discarding the packing material, check that all parts and

accessories are accounted for (included accessories are listed in Section 1.3). If any are missing, please

notify the factory in writing.

If your keyboard is in kit form, check the parts against the list in Section 7 of this manual. Then turn to

Section 5 for assembly instructions.

2.2 Preliminary Checkout

Connect the power cord to an AC source of the proper voltage and frequency.

NOTE: The keyboard can be connected for either 105 to 125 volt or 210 to 250 volt operation. Factory-

assembled units are wired for nominal 115 volt input unless otherwise indicated by a tag attached to

the power cord. Before connecting the power cord, be certain that the voltage of the outlet

corresponds to the keyboard input voltage rating.

To ensure operator safety, connect the power cord to a three-prong outlet with safety ground. DO NOT

attempt to defeat the grounding prong of the keyboard cordset. To do so will void the warranty.

Next, rotate the mode switch to the Morse position. Switch the keyboard on by rotating the volume

control clockwise to about the center of its range. When power is first applied, the identifier and the three-

character memory circuits may be in their active states. If so, the stored characters will be clocked out of

the memory in rapid succession. Wait until the process is complete. Then press any of the letter or number

keys. The keyboard should produce a keyed audio tone corresponding to the Morse code pattern of dots and

dashes for the character. Test several other keys, adjusting the speed, volume, and weight controls to check

their operation. If this preliminary test is satisfactory, the keyboard is ready to be connected to your CW

transmitter and RTTY loop circuit.

If the keyboard will be used for both RTTY and Morse operation in your station, prepare the connecting

cables described in Sections 2.3 and 2.4. The keyboard may be left connected to both the RTTY loop and

the CW transmitter; it is not necessary to exchange cables or remove plugs when changing modes, as the

RTTY and Morse output stages of the keyboard are completely independent. Of course, the keyboard need

not be used for both modes. In that case, simply prepare cables for the appropriate output Jacks and leave

the others unconnected.

BEFORE PROCEEDING WITH THE INSTALLATION, DISCONNECT THE AC POWER CORD.

2.3 CW Transmitter Keying Connections

The keyboard Morse output stage is a high-voltage switching transistor. When connected to the

transmitter, this electronic switch takes the place of the normal hand key. The keyboard may be connected

for either cathode or grid-block keying (but not both at the same time), depending on which of the two

rear-panel keying jacks is used. The two Morse output connections may not be used at the same time. The

Morse output control circuitry is shown in Figure No. 8.11.

Before attempting to connect the keyboard to the transmitter keying terminals, examine the transmitter

circuit diagram carefully to determine the keying method used. The keyboard cannot be used with "floating"

key circuits; one of the two keying terminals must be grounded within the transmitter.

The transistor keying switch is rated to withstand 250 volts at up to 150 mA in cathode keying service.

For grid-block keying, the voltage at the key should not exceed -150 volts, and the current should not be

greater than 150 mA. Before connecting the keyboard, measure the voltage across the keying terminals of

the transmitter with the key open and the current through the key when it is closed to ensure that these

ratings are not exceeded.

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