TAPR TAPR,9600Bps,modem User guide

Page 1

T A P R

Tucson Amateur Packet Radio

TAPR 9600bps Modem Manual

Reproduction or translation of any part of this work beyond that permitted by sections 107 or 108 of the 1976 United States Copyright Act (or its legal successor) without the express written permission of Tucson Amateur Packet Radio Corporation is unlawful except as noted below. Requests for permission to copy or for further information should be addressed to Tucson Amateur Packet Radio Corporation. Except as noted above, permission is hereby granted to any non-profit group or individual to reproduce any portion

of this document provided that: the reproduction is not sold for profit; the intent of the reproduction is to further disseminate information on Amateur Packet Radio; the reproduction is not used for advertising or otherwise promoting any specific commercial product; full credit is given to Tucson Amateur Packet Radio Corporation (including address) as the original source of information; and Tucson Amateur Packet Radio Corporation is notified in writing of the reproduction.

The information contained in this document has been carefully checked and is believed to be entirely reliable. However , no responsibility is assumed for inaccuracies. T ucson Amateur Packet Radio Corporation (TAPR) r eserves the right to make changes in any products to improve reliability , function or design without obligation to purchasers of previous equipment. T APR does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey license under its patent rights or the rights of others.

INTRODUCTION................................................. 1

PARTS LIST ........................................................... 2

CONSTRUCTION NOTES .................................. 3

CONSTRUCTION ................................................ 4

INSTALLATION

TNC 2 Internal Installation...............................8

PK232 Internal Installation ............................. 10

PK232MBX (without daughterboard) ........... 12

PK-88 ..............................................................15

PCB-88..............................................................17

DRSI PCPA ......................................................18

TNC 1 ..............................................................19

PacComm Tiny-2.............................................20

Generic Installations ....................................... 21

FINAL CHECKOUT............................................ 23

Alternate Deviation Setting Method .............23

HARDWARE

Detailed Circuit Description...........................23

Jumper Functions............................................ 25

Radio Connector - P1 ......................................26

Modem Disconnect - P3..................................26

Secondary Modem Disconnect - P2 ...............27

ERRA TA for Secondary Modem Disc ...........28

TROUBLESHOOTING........................................ 29

Equipment Needed.........................................29

Checking It Out ............................................... 29

Where to Look for Missing Signals................30

Waveform 1 & 2...............................................31

Clock & Bit Regenerator Options.........................31

INTRODUCTION

The T APR 9600 bps modem is an accessory for packet experimenters developing higher-speed rf links. This is a new design from T APR and was tested for several months prior to this release. This new design is derived from the pioneering efforts of Steve Goode, K9NG and James Miller, G3RUH. TAPR extends its gratitude to those individuals who assisted in the design and release of this modem and Gary Hauge, N4CHV, Lyle Johnson, WA7GXD and Bob Nielsen, W6SWE for this documentation.

These notes are intended to aid the builder of the TAPR 9600 bps modem kit. Refer to the additional documentation (included with this kit) for a detailed circuit description, operational hints and operating principles. This kit includes all parts and components necessary to fully populate the PC board and mating connectors. It does NOT include the case, front panel, rear panel power connector, knobs, fuses, etc.

Access to test equipment, including a voltmeter and oscilloscope is required to align the modem and verify its performance. An ohm meter would be very helpful in identifying some resistor values.

This manual provides sufficient information for the advanced experimenter to build, align and operate the 9600 bps modem.

8987-309 E. Tanque Verde Rd #337 Tucson, Arizona ¥ 85749-9399

Office: (817) 383-0000 ¥ Fax: (817) 566-2544

Non-Profit Research and Development Corporation

9600bps

9600bps Modem Kit January 1993 Page 1 of 38

Page 2

Please check the shipment for any possible errata sheet(s) and/or additions/corrections to instructions provided in this manual.

NOTE: Please read the Construction notes prior to starting assembly.

ACKNOWLEDGEMENTS

The Tucson Amateur Packet Radio (TAPR) 9600 bps Modem Kit was made possible by the pioneering efforts of Steve Goode, K9NG and James Miller, G3RUH and the active participation of a number of Amateur Radio operators and organizations worldwide. While the following list is by no means complete, TAPR wishes to acknowledge their contribution to this effort.

Individuals: Chuck Green, N0ADI Eric Gustafson, N7CL Lyle Johnson, WA7GXD

( ) (2) 23.7K Ω R8, R9

(2372) or (red-orange-violet-red-white)

( ) (2) 4.75K Ω R30, R31

(4751) or (yellow-violet-green-brown-white)

Resistor (Network - 10 pin)

( ) (2) 10K Ω (103) RP1, RP2

Resistor, (Trimpot, Single-Turn)

( ) (2) 10K Ω (103) R11, R21

Diodes

( ) (2) 1N4148 D2, D6 ( ) (3) LED D3, D4, D5

Capacitors, Ceramic Monolithic, Z5U

( ) (23)0.1 uF (104) C7, C9, C11, C12, C18, C21,

C25, U7, U8, U9, U10, U1 1, U12, U13, U14, U15, U16, U17, U18, U19, U20, U21, U22

...and the builders of the first run kits whose feedback made this version of the manual possible.

Kit Builders: Mike Curtis, WD6EHR Jack Davis, WA4EJR Chuck Green, N0ADI Gary Hauge, N4CHV Lyle Johnson, WA7GXD Bob Nielsen, W6SWE

Capacitors, Ceramic Monolithic, X7R

( ) (4) 0.001 uF (102) C1, C2, C3, C4

Capacitors, Ceramic Monolithic, COG

( ) (2) 100 pF (101) C5, C6 ( ) (1) 330 pF (331) C23 ( ) (1) 560 pF (561) C13 ( ) (3) 2200 pF (222) C15, C16, C26 ( ) (1) 2700 pF (272) C27

PARTS LIST

This parts list is organized by quantity and part type. Please verify that all parts are present, checking the space provided. You may wish to take this opportunity to sort the parts into a compartmented container , such as an egg carton or muf fin tin.

Resistors (1/4 w, 5% Carbon Film):

( ) (1) 10 Ω R6 ( ) (1) 100 Ω R1 ( ) (1) 330 Ω R23 ( ) (5) 470 Ω R2, R14, R19, R20,

R24 ( ) (2) 1K Ω R3, R15 ( ) (2) 2.2K Ω R26, R27 ( ) (6) 10K Ω R4, R5, R18, R32, R32,

R34 ( ) (1) 33K Ω R25 ( ) (1) 68K Ω R12 ( ) (2) 100K Ω R13,R28 ( ) (2) 220K Ω R17, R22 ( ) (1) 300K Ω R29

(brown-black-black-gold)

(brown-black-brown-gold)

(orange-orange-brown-gold)

(yellow-violet-brown-gold)

(brown-black-red-gold)

(red-r ed-r ed-gold)

(brown-black-orange-gold)

(orange-orange-orange-gold)

(blue-grey-orange-gold)

(brown-black-yellow-gold)

(red-red-yellow-gold)

(orange-black-yellow-gold)

Resistors (1/4 w, 1%, Metal Film)

( ) (1) 12.1K Ω R10

Page 2 of 38 January 1993 9600bps Modem Kit

(1212) or (brown-red-brown-r ed-white)

Capacitors

( ) (1) 1 uF (105) C24 ( ) (6) 10 uF (106) C10, C14, C17, C28, C29, C30 ( ) (1) 100 uF (107) C22

IC Sockets

( ) (2) 08 pin U4, U5 ( ) (8) 14 pin ( ) (2) 16 pin U12, U20 ( ) (4) 20 pin U13, U14, U16, U18 ( ) (2) 28 pin U15, U17

Transistor

( ) (1) VN10KM Q1

Connectors

( ) (4) 2-pin Male Header JP2, JP3, JP5, JP6 ( ) (1) 2-pin Shell ( ) (2) 2-pin Shunt ( ) (1) 3-pin Male Header JP4 ( ) (1) 5-pin Right Angle Male Header P1 ( ) (1) 5-pin Shell ( ) (1) 20-pin Male Header P2 ( ) (1) 26-pin Male Header P3 ( ) (1) 20-pin Female Header P3 ( ) (7) Pins for Shells

, Electrolytic, Radial Lead (POLARIZED)

U7, U8, U9, U10, U11, U19, U21, U22

Page 3

Integrated Circuits

Note: Do not handle chips at this time.

( ) (1) 16V8 or 18CV8 U13 ( ) (1) 16V8 or 18CV8 U14 ( ) (1) 27C64, STATE 2.00 U15 ( ) (1) 27C64, TX9600 1.00 U17 ( ) (2) CD4006B U8, U10 ( ) (1) 74HC14 U19 ( ) (2) 74HC74 or 74HCT74 U7, U9 ( ) (1) 74HC86 or 74HCT86 U11 ( ) (1) 74HC393 or 74HCT393 U21 ( ) (2) 74HC574 or 74HCT574 U16, U18 ( ) (1) 74HC4538 U12 ( ) (1) AD7523 U20 ( ) (1) LM393 U4 ( ) (1) LM7805 U23 (REGULA TOR) ( ) (1) TL082 U5 ( ) (1) TL084 U22

Miscellaneous

( ) (1) PC Board, 9600 Modem Rev 1 ( ) (1) Assembly Manual (This Document)

CONSTRUCTION NOTES:

******** CAUTION ********

It is recommended that when assembling the TAPR 9600 bps modem kit, that you use a very fine pointed soldering tip on an iron of r elatively low wattage (25 watts maximum, 15 watts is ideal). Due to the proximity of some of the traces on the PC board, solder bridges are a very distinct possibility. A low wattage soldering iron, fine pointed tip, clean rosin core solder (small size) is the order of the day. Following these points could eliminate several hours of troubleshooting (or worse). This is good practice when working on any kit.

The accompanying component placement drawing shows the placement of all parts on the circuit boar d. Pay particularly close attention to:

1) U1, U2, U3, and U6 are not included with the basic modem kit. These are options available from TAPR.

NOTE: Shaded Parts are contained in the modem options only. These parts should be ignored if building without the clock option or bit regen option. These are not needed with all kits.

9600bps Modem Clock Option:

( ) (1) 0.1 uF U6 (104) ( ) (2) 22 pF C19, C20 (220 or 22J)

( ) (1) 10M Ω R16 (br own-black-blue-gold) ( ) (1) 16-pin socket U6 ( ) (1) 74HC4060 U6 ( ) (1) Crystal Y1 (4.9152 MHz)

9600bps Modem Bit Regenerator Option

( ) (1) 100K ohm R7 (br own-black-yellow-gold) ( ) (4) 0.1 uF (104) C8, U1, U2, U3 ( ) (1) 14-pin socket U3

( ) (1) 16-pin socket U2 ( ) (1) 20-pin socket U1

( ) (1) 1N4148 D1 ( ) (1) 16V8 or 18CV8 U1

( ) (1) 74HC14 U3 ( ) (1) CD40105B U2

2) When mounting the Electrolytic Capacitors note that laying them down flat against the board (as outlined) will help provide the required space if the modem is to be mounted into a TNC.

3) Identifying the pins on headers P2 and P3. Looking at the modem board from the top of the board you will find pin-1 at the lower right hand position on the connectors (the square pad on the connector). There is a silkscreen dot near this pin.

4) Some resistor values may seem unclear as to color and value. Be very sure of value prior to installation. Access to an ohm meter will be very helpful.

5) Save the clipped leads from the resistors and capacitors as some of these will be used to fabricate test lead points.

6) Read this entire document prior to starting

construction of your kit. There are several final configurations for the 9600 bps modem (depending on which type of TNC you have) and some parts may or may not require installation for your specific configuration.

9600bps Modem Kit January 1993 Page 3 of 38

Page 4

CONSTRUCTION

R34

U20 U21 U22

R32 R33

C28 C29 C30

C24

R25

U18 U19

TP3

C25

R26

R27

C23

C27

C26

JP6

TNC MODEM

R28

R29

R30

R31

R18

R19

R20

JP1

R24

R22

R23

U12

C21

R17

C22

PTTPWR

DCD

R21

U7 U8

U11

U10

R16

C20

C19

GND

TP2

R11

C17

C18

U16

U17

R12

R13

R14

R15

C11 U15

C13 C15 C16

R8 R9

R10

C12

C14

C10

U23U3

R1 R2

TP1

U14

U13

RP1

RP2

JP2

JP3

JP4

JP5

INT CLK

TNC1 TNC2

Check the PC Board and verify that the exposed, tinned pads are clean and shiny. If they are not, scrub the board LIGHTLY with a household cleanser (such as "AJAX" or "COMET") and rinse with clean water, then dry with a clean soft towel.

( ) PC board clean Refer to the layout diagram in Figure 1 for clarification

of parts placement. Figure 1 is also attached as a full size diagram at the end of the manual.

NOTE: Shaded Parts are contained in the modem options only. These parts should be ignored if building without the clock option or bit regen option. These are not needed with all kits.

( ) U14 20 pin IC socket ( ) U15 28 pin IC socket ( ) U16 20 pin IC socket ( ) U17 28 pin IC socket ( ) U18 20 pin IC socket ( ) U19 14 pin IC socket ( ) U20 16 pin IC socket ( ) U21 14 pin IC socket ( ) U22 14 pin IC socket

Bit Regen Option

( ) U1 20 pin IC socket ( ) U2 16 pin IC socket ( ) U3 14 pin IC socket

Clock Option

( ) U6 16 pin IC socket

IC Sockets

NOTE: The IC sockets are polarized, with the end

nearest pin 1 marked with a notch, beveled corner or numeral 1 embossed in the body of the socket. ( ) U4 08 pin IC socket ( ) U5 08 pin IC socket ( ) U7 14 pin IC socket ( ) U8 14 pin IC socket ( ) U9 14 pin IC socket ( ) U10 14 pin IC socket ( ) U11 14 pin IC socket ( ) U12 16 pin IC socket ( ) U13 20 pin IC socket

Page 4 of 38 January 1993 9600bps Modem Kit

Figure 1 - Component Layout

Resistors

Resistor leads are on 0.5" centers. A lead-bending jig may be used to help ensure best appearance of the completed kit. The resistors mount flat against the PC board. ( ) R1 100 ohm brown-black-brown-gold ( ) R2 470 ohm yellow-violet-brown-gold ( ) R3 1K ohm brown-black-red-gold ( ) R4 10K ohm brown-black-orange-gold ( ) R5 10K ohm brown-black-orange-gold ( ) R6 10 ohm brown-black-black-gold

( ) Solder and clip twelve (12).

Page 5

( ) R8 23.7K ohm 1%

2372 or red-orange-violet-red-white

( ) R9 23.7K ohm 1%

2372 or red-orange-violet-red-white

( ) R10 12.1K ohm 1%

1212 or brown-red-br own-r ed-white ( ) Solder and clip six (6) leads. ( ) R12 68K ohm blue-grey-orange-gold

( ) R13 100K ohm brown-black-yellow-gold ( ) R14 470 ohm yellow-violet-brown-gold ( ) R15 1K ohm brown-black-red-gold

( ) Solder and clip eight (8) leads. ( ) R17 220K ohm red-r ed-yellow-gold

( ) R18 10K ohm brown-black-orange-gold ( ) R19 470 ohm yellow-violet-brown-gold

NOTE: If you intend to use the modem inside a TNC 2 and wish to use the DCD LED on the TNC to indicate the DCD status of the 9600 modem, DO NOT install R20.

( ) R20 470 ohm yellow-violet-brown-gold ( ) R22 220K ohm red-r ed-yellow-gold ( ) R23 330 ohm orange-orange-brown-gold

Bit Regen Option

( ) R7 100K ohm brown-black-yellow-gold

Clock Option

( ) R16 10M ohm brown-black-blue-gold

Resistor Networks

The next parts are resistor SIP networks. These are polarized parts; the end with the dot or stripe goes into the square pad. When installing SIPs, tack solder the end pins, verify placement against the PCB, then solder the remaining pins. Finally, re-solder the two end pins.

( ) RP1 10K ohm SIP (103) ( ) RP2 10K ohm SIP (103)

Trimpots

Some models of trimpots have leads that "snap" into the board. In any case, be sure the trimpot leads extend approximately 1 mm below the board before soldering.

( ) R11 10K ohm TRIM (103) ( ) R21 10K ohm TRIM (103)

NOTE: If you intend to use the modem inside a TNC 2 and wish to use the PTT LED on the TNC to indicate the PTT status of the 9600 modem, DO NOT install R24.

( ) R24 470 ohm yellow-violet-brown-gold ( ) Solder and clip ten (10), twelve (12), fourteen (14).

( ) R25 33K ohm orange-orange-orange-gold ( ) R26 2.2K ohm red-red-r ed-gold ( ) R27 2.2K ohm red-red-r ed-gold ( ) R34 10K ohm brown-black-orange-gold

( ) Solder and clip six (8) leads.

( ) R28 100K ohm brown-black-yellow-gold ( ) R29 300K ohm orange-black-yellow-gold ( ) R30 4.75K ohm 1%

4751 or yellow-violet-green-brown-white ( ) R31 4.75K ohm 1%

4751 or yellow-violet-green-brown-white ( ) Solder and clip eight (8) leads.

( ) R32 10K ohm brown-black-orange-gold ( ) R33 10K ohm brown-black-orange-gold

( ) Solder and clip four (4) leads.

( ) Check placement of components & solder in place. You should have no remaining resistors (except

possibly R20 and R24). ( ) No unexpected resistors left over.

Capacitors

NOTE: Capacitor locations with no "C" designator,

but with filled-in dot in the part outline, are bypass capacitor locations. These will be installed later .

Electrolytic capacitors are polarized. The positive lead goes in the hole location on the board marked with a "+". The PCB pad is square for the positive lead. The capacitors themselves usually have the negative lead marked, so be careful!

Install the following capacitors: ( ) C1 0.001 uF (102) ( ) C2 0.001 uF (102) ( ) C3 0.001 uF (102) ( ) C4 0.001 uF (102) ( ) C5 100 pF (101) ( ) C6 100 pF (101) ( ) C7 0.1 uF (104) ( ) C9 0.1 uF (104)

( ) Solder and clip sixteen (16) leads.

9600bps Modem Kit January 1993 Page 5 of 38

Page 6

( ) C10 10 uF (106) Polarized ( ) C11 0.1 uF (104) ( ) C12 0.1 uF (104) ( ) C13 560 pF (561) ( ) C14 10 uF (106) Polarized ( ) C15 2200 pF (222) ( ) C16 2200 pF (222)

( ) Solder and clip fourteen (14) leads.

Bit Regen Option

( ) C8 0.1 uF (104) Bypass capacitors are installed in the capacitor

outlines marked with a filled in dots. They have no "C" designator . ( ) U1 0.1 uF (104) ( ) U2 0.1 uF (104) ( ) U3 0.1 uF (104)

( ) C17 10 uF (106) Polarized ( ) C18 0.1 uF (104) ( ) C21 0.1 uF (104)

The marking for C21 is obscured by the socket for U9 (See Fig. 1).

( ) C22 100 uF (107) Polarized ( ) Solder and clip eight (8) leads. ( ) C24 1 uF (105) Polarized

( ) C23 330 pF (331) ( ) C25 0.1 uF (104) ( ) C26 2200 pF (222) ( ) C27 2700 pF (272) ( ) C28 10 uF (106) Polarized ( ) C29 10 uF (106) Polarized ( ) C30 10 uF (106) Polarized

( ) Solder and clip sixteen (16) leads.

Bypass Capacitors

Bypass capacitors are installed in the capacitor outlines marked with a filled in dots. They have no "C" designator . ( ) U7 0.1 uF (104) ( ) U8 0.1 uF (104) ( ) U9 0.1 uF (104) ( ) U10 0.1 uF (104) ( ) U11 0.1 uF (104) ( ) U12 0.1 uF (104)

( ) Solder and clip twelve (12). ( ) U13 0.1 uF (104)

( ) U14 0.1 uF (104) ( ) U15 0.1 uF (104) ( ) U16 0.1 uF (104) ( ) U17 0.1 uF (104)

( ) Solder and clip ten (10) leads. ( ) U18 0.1 uF (104)

( ) U19 0.1 uF (104) ( ) U20 0.1 uF (104) ( ) U21 0.1 uF (104) ( ) U22 0.1 uF (104)

( ) Solder and clip ten (10) leads.

Page 6 of 38 January 1993 9600bps Modem Kit

( ) Solder and clip eight (8) leads.

Clock Option

( ) C19 22 pF (220 or 22J) ( ) C20 22 pF (220 or 22J)

Bypass capacitors are installed in the capacitor outlines marked with a filled in dots. They have no "C" designator . ( ) U6 0.1 uF (104)

( ) Solder and clip six (6) leads.

This completes the capacitor installation. You should have no remaining capacitors.

( ) No capacitors remaining.

Diodes

NOTE: Diodes are polarity sensitive devices. Diodes

are mounted flat near the surface of the board like the resistors previously installed. The cathode end of the diode is banded, and corresponds to the banded silkscreen legend and the square pad on the PCB.

Install the following diodes: ( ) D1 1N4148 (Bit Regen Option) ( ) D2 1N4148

( ) D6 1N4148 ( ) Solder and clip four (4) or six (6) leads.

Light Emitting Diodes (LEDs)

LEDs are polarized components. They usually do not have their part value stamped on them. The cathode end of the LED is indicated by a flat side on the body of the part. LEDs also have their cathode lead shorter than their anode lead. The cathode lead is the one which goes into the square pad on the PCB.

NOTE: If you are installing the 9600 bps modem inside a TNC 2, you may wish to use the TNC 2 LEDs for both 1200 (normal) operation as well as 9600 bps operation. If this is the case, DO NOT install the LEDs D3, D4 and D5.

Page 7

Depending on your installation, you may wish to leave enough lead length on the LEDs to bend them over the edge of the PC board. Or , you may wish to mount them flush to the top surface of the PC board. Check the mechanical clearances in your proposed location for the modem, then proceed to install the LEDs.

( ) D3 LED ( ) D4 LED ( ) D5 LED

( ) Solder and clip zero (0) or six (6) leads.

Transistor

NOTE: The transistor is a power field-effect type

(FET), selected for keying a radio transmitter. The metal tab on the transistor body is connected to the drain, which is the signal for keying the radio. Mount the body of this transistor close to the PC board to ensure the tab does not come into contact with the metal cabinet of the TNC (if mounting into a TNC). If the tab were to come into contact with the case, either an intermittent or steady key of the radio will result.

( ) Q1 VN10KM

Test Points

Test points are formed from the clipped leads of the installed resistors or capacitors. Form a lead into a loop of about 1/8" (3 mm) diameter (wrap one loop around a drill bit or similar item). The loop should stick up about 1/4" (6 mm) from the PC board so you can easily attach an alligator clip or test probe to it.

( ) TP1 EYE ( ) TP2 RXCLOCK ( ) TP3 BER ( ) GND

Installation of specific parts

The modem is nearly complete. Every part should be installed except the Integrated Circuits, connectors P1, P2 and P3, voltage regulator U23, and possibly R20, R24 and the LEDs (depending on your specific TNC installation).

Check your work for incorrect soldering and parts installation prior to completing the modem kit.

( ) Everything looks simply wonderful to me!

( ) Solder and clip three (3) leads.

Male Headers

The 2-, 3-, and 20-pin male headers will next be installed. The plastic body of the part should rest flush with the top surface of the PC board. The short end of the pins goes into the PC board, the long end sticks up.

WARNING: Do not hold these parts with your fingers as they quickly get very hot while soldering in place.

( ) JP2 2 pin ( ) JP3 2 pin ( ) JP4 3 pin ( ) JP5 2 pin ( ) JP6 2 pin ( ) P2 20 pin

CrystalCrystal: (Clock Option)

The crystal, which is part of the clock option, should lay flat against the surface of the PC board. Do not bend the leads sharply at the body of the crystal; instead, form a large radius curve with the leads to act as a strain relief.

The next section of these instruction deals with configuring the modem to your particular installation. If you are installing the modem in a TAPR TNC 2 or clone, PK232 or PK232MBX, specific directions are given. If you are installing the modem in another TNC, you may proceed to the section headed GENERIC INSTALLA TIONS. Specific dir ections for several other TNCs are given, however much of the required information is contained in the GENERIC INSTALLATIONS section. You should also read the sections on the TNC-2 and PK232 for ideas and hints that may apply to your TNC.

( ) Y1 Crystal 4.9152 MHz ( ) Solder and clip two (2) leads.

9600bps Modem Kit January 1993 Page 7 of 38

Page 8

TNC 2 Internal Installation

Modem Preparation

NOTE: If you wish to use the TNC 2's existing LEDs

as indicators for the 9600 modem, perform the following steps.

PTT

( ) Install a 1N4148 diode at R24 with the cathode

near the notched portion of the board.

DCD

( ) Obtain and install a 1N4148 diode at D5 with the

cathode to the square pad. ( ) Obtain and install a 10K resistor at R20. ( ) Cut the trace tying pads at JP1 (trace is on bottom

of board).

( ) Install the 5-pin right angle male header at P1. It

will overhang the PC board, with the pins pointing

away from the modem board.

( ) Install the 20-pin female header on the bottom of

the modem PC board at location P3 to occupy pins

1 through 20. (Viewing the connector socket from

the bottom side of the board, pin 1 is the square pad.) ( )

Cut the provided 26-pin male header to a 20-pin length.

( ) Cut a 2-pin header from the remaining 6-pin

portion of the 26-pin header. ( ) Install this 2-pin header to pins 24 and 26 on the

top of the board at location P3.

( ) In general, no component on the TNC 2 PC boar d

that will lie beneath the modem should protrude from the top of the PC board higher than a socketed IC.

NOTES:

1. In many cases, the LM324 (or LM348)␣op amp at U3 may not be fast enough for reliable operation at 9600 bps on the serial post to the computer. In that case, replace U3 with a TL084 or TL094 or equivalent.

2. If you desire to run the serial port to the computer at 19200bps, cut the trace that goes from pin 1 of swtich SW to pin 2 of divider U1. Connect a wire from pin 10 of U1 to pin1 of SW2. SW2 swtich 1 will now select a data rate of 19200 bps instead of 300 bps. change above will be required in addition to this change.

Power Wire

( ) Solder a wire to a push-on shunt. This will be your

+12-volt DC connector to the modem.

( ) Solder the other end of the wire to the positive

end of C12 on the TNC 2 PCB.

Initial Checkout

( )

Provide a heatsink for the TNC 2 voltage r egulator Q3. ( ) Plug the modem into the TNC. ( ) Attach the +12-volt DC connector to the header

installed at pins 24 and 26 of P3. ( ) Apply power to the TNC and verify that +5-volts

appears across pins 7 and 14 of IC location U3 on

the modem board. ( ) Remove power from the TNC.

The op amp

U23

( ) Install the LM7805 voltage regulator at U23 on the

modem boar d. The regulator should lay flat against the surface of the board. There is no need to fasten the regulator with scr ews as the modem draws very little current and the regulator will not overheat.

TNC 2 Preparation

( ) If the TNC 2 lacks a modem disconnect header at

J4, cut the traces on the bottom of the TNC PC board between J4 pin pairs 1&2, 5&6, 9&10, 1 1&12, 13&14, 17&18, 19&20.

( ) Install the 20-pin male header on top of the TNC

2 PC board at J4.

( ) Crystal Y1 on the TNC 2 must lay down flat. You

may have to unsolder and lengthen the leads to accomplish this.

( ) Jumpers or connectors at JMP6, JMP9, JMP10 and

J5 may have to be clipped to ensure they do not touch the modem PC board.

Page 8 of 38 January 1993 9600bps Modem Kit

( ) Remove the modem from the TNC. Observing static handling precautions, install the

following ICs on the modem: ( ) U4 LM393 ( ) U5 TL082 ( ) U7 74HC74 ( ) U8 CD4006B ( ) U9 74HC74 ( ) U10 CD4006B ( ) U11 74HC86 ( ) U12 74HC4538 ( ) U13 16V8 or 18CV8 ( ) U14 16V8 or 18CV8 ( ) U15 27C64 labelled "ST ATE 2.0" ( ) U16 74HC574 ( ) U17 27C64 labelled "TX9600 1.0" ( ) U18 74HC574 ( ) U19 74HC14 ( ) U20 AD7523 ( ) U21 74HCT393 ( ) U22 TL084

Page 9

Bit Regen Option ( ) U1 16V8 or 18CV8 BitRegen ( ) U2 CD40105B ( ) U3 74HC14

Clock Option ( ) U6 74HC4060

NOTE: If you use a switch, and if you have the internal clock option installed and selected on the modem, the radio port data rate will automatically be selected according to the modem in use. The TNC 2 DIP switch may then be left at the 1200 (or 300) bps selection.

( ) Leave the TNC 2 out of the case.

Check for proper installation of all IC chips. Be especially careful about pins folded under chip bodies, or overhanging the side of a socket.

( ) Install a shunt on JP3. ( ) Install a shunt on JP4 pins 2&3 (directly beneath

the shunt on JP3).

( ) Install a shunt on JP2 only if you are using the

clock option.

( ) Bend the leads of the header JP6 to form a right

angle with the connector pointed towards the front panel of the TNC 2.

( ) Install a lead from the cathode end of D3 to the

cathode end of CR21 on the TNC 2 PC board.

( ) Install a lead fr om the ungrounded pad of JP1 (the

round pad, not the square one) to the cathode (banded) end of CR15 on the TNC 2 PC board (near the modem disconnect header of the TNC).

( ) Install the modem on the TNC 2 and verify that

no contact is made between jumpers or other conductors on the TNC 2 PCB to the bottom of the modem PCB.

( ) Locate the front panel of the TNC 2 and note the

location of the notch on the modem PCB. Drill an appropriate hole for a SPST switch to be mounted on the front panel of your TNC 2. It will be located between the T APR logo and the LED labels.

( ) Attach a 2-pin female header to the switch, using

short, flexible leads and the provided connector into JP6 on the modem board.

( ) Plug the 2-pin connector into JP6 on the modem

PC board.

( ) Set the switch to the open position. This selects

9600 bps operation and will be needed for the tests that follow.

( ) Apply power to the TNC and verify that the TNC

signs on as normal. NOTE: If the TNC seems sluggish, or takes a long

time to reset, or never resets and signs on, check your power supply voltage to the TNC. The modem adds 50 mA or so of current drain, and a marginal power supply may cause the system to exhibit this symptom. The modem is not at fault; replace the power supply before proceeding!

( ) Place a jumper across pins 1 and 2 of modem

connector P1. ( ) Preset R11 on the modem board to full CCW, then

1/8 turn CW. ( ) Preset R21 to mid-range. ( ) Command your TNC to ignore DCD. This is the

FULLDUP ON command if you are using TAPR

firmware. ( ) Note that the modem's DCD LED is now on. This

tells you that the modem is "hearing" and decoding

its transmit data via the loopback connection. ( ) Issue a connect to yourself. This will check out

the receive decode portion of the modem. Note

that the PTT LED will flash on the modem. You may restore normal operation to your TNC by

placing a shunt on JP6 (or closing a switch wired to JP6), and setting the radio port data rate to whatever data rate you normally use via the DIP switch on the rear of the TNC 2 (this is automatic if you are using the internal clock option). Remember to reset FULLDUP OFF or your transmitter will gleefully step on other stations' signals!

At this point, initial checkout is complete. You will next have to interface the unit to your radio, modify the radio as necessary, and set the R11 compensation and R21 output level for the correct transmitter deviation.

( ) If you have NOT installed the clock option on the

modem, set the TNC 2 radio data rate to 9600 bps using the DIP switch on the back of your TNC and ensure that no shunt is on JP2.

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information.

When you have performed the interface, proceed to the section in this manual entitled FINAL

CHECKOUT.

9600bps Modem Kit January 1993 Page 9 of 38

Page 10

PK232 Internal Installation

TOP

PIN 1

PIN 2

PIN 20

PIN 1

PIN 2

PIN 20

8 inches

The following directions apply to PK232s with the PakMail option installed as a daughterboard. PK232MBX units which do not have a daughterboard are covered in a later section of this manual. This section assumes you have the TAPR PK232 Modem Disconnect Header modification kit. If you do not, one may be obtained from T APR. If you prefer to not use the modem disconnect, see below for further instructions. In addition to the TAPR Modem Disconnect kit, you may wish to use the TAPR PK232MBX Installation kit, which contains prewired plug ‘n’ play harness and all hardware needed for installing the 9600 bps modem inside your PK232MBX.

Modem Preparation

Perform the following steps to complete assembly of your modem prepared for internal PK232 installation.

U23

( ) Install the LM7805 voltage regulator at U23 on the

modem board. The regulator should lay flat against the surface of the board. There is no need to fasten the regulator with screws as the modem draws very little current and the regulator will not overheat.

P1 NOTE: The 5-pin right-angle male header will be

installed on the BOTTOM side of the modem PC board. ( ) Place the 5-pin right angle connector on the bottom

(solder) side of the modem PC board. It should rest on the bottom surface of the board. The pins from the connector should "point" towards the PC board, not away from it. See illustration below.

( ) Cut a 2-pin header from the remaining 6-pin

portion of the header used for P3. ( ) Solder this connector to pins 24 and 26 of location P3.

Jumpers

( ) Be sur e you have NO shunts installed at JP2, JP3,

JP4, JP5 or JP6.

Options

( ) The CLOCK option, if installed, must be disabled

by leaving JP2 open. ( ) The BIT REGENERA TOR option, if installed, must

be removed. This is done by simply removing

ICs U1, U2 and U3 from their sockets.

Cabling

( ) Fabricate an 8" (20 cm) long cable with a 20-pin

female IDC header at each end, such that pins 1

are tied together, pins 2 are tied together, etc.,

through pins 20.

( ) Check the clipped leads from R1-R6 and C1-C9

and verify that they are flush, or nearly flush, with the PC board. Clip and reheat the connections as necessary. This will ensure proper fit of the mating connector , attached later.

( ) Solder the 5 pins of the connector to the top of the

PC board.

Study the illustration below before mounting P3. ( )

Cut the supplied 26-pin male header to a 20-pin header .

( ) Solder the header to the PC board so it occupies

pins 1 through 20 of P3. The short pins go into the PC board; the long pins stick up fr om the top of the PC board.

Page 10 of 38 January 1993 9600bps Modem Kit

( ) Fabricate a 6" (15 cm) long single-wire cable using

a two-pin header shell at each end. ( ) Fabricate a 7" (17.5 cm) long cable with a push-on

shunt at one end and the other end free. ( ) Fabricate a 5-wir e cable 4" (10 cm) long using a 5-

pin connector shell using ribbon cable as follows:

Pin 1 Brown Pin 2 Red Pin 3 Orange Pin 4 Yellow Pin 5 Green

Page 11

PK232 Preparation

PK232 MOTHERBOARD [TOP SIDE]

C62

JP4

JP5

BROWN RED

GREEN

ORANGE YELLOW

J10

CUT HERE

( ) Remove the case fr om the PK232 by removing the

six (6) screws that fasten it together.

The other end at the JP6 pin nearer the silkscr een

legend "U22" on the modem board. ( )

Form the 20-pin cable into a "Z" shape as shown below .

( ) If you have not already done so, fabricate, install

and checkout the TAPR PK232 Modem Disconnect kit.

( ) Using a sharp knife, carefully cut the trace from

Pin 5 of J8 (external modem connector) on the top of the PC board as shown below.

( ) Insert one end into the modem header P3, with

pin 1 near the silkscreened dot on the board. ( ) Remove any jumpers fr om the Modem Disconnect

header P1.

( ) Ensur e jumpers JP4, JP5 and JP6 on the PK232

motherboard are installed at the center and inboard pins (away from the back edge of the PK232).

( ) Solder the five (5) wires from the five-wire cable

fabricated above to the PK232 motherboard as follows:

Brown JP4 pin nearest back edge of PK232 Red JP5 pin nearest back edge of PK232 Orange Yellow

Exposed lead of C62 bearer back edge of PK232 Exposed lead of C62 bearer back edge of PK232

Green Feedthrough just inboard of J8 Pin 5

( ) Solder the free end of the lead with the shunt

attached to either center pin of SW1.

( ) Remove the two screws on the PK232

motherboard in the center (one at the rear edge between J7 and J8, the other near U30 and Q10 towards the front panel of the unit).

Modem Integration

( ) Attach the 5-pin connector fr om the cable soldered

to the PK232 motherboard near J8 to P1, on the underside of the modem.

( ) Insert the other end of the 20-pin cable into the

Modem Disconnect header, P1, with pin 1 near

the silkscreen legend "P1".

Initial Checkout

Apply power to the modem and verify that +5 volts appears between U13 pin 20 and U13 pin 10.

Remove power from the modem and install the following ICs: ( ) U4 LM393 ( ) U5 TL082 ( ) U7 74HC74 ( ) U8 CD4006B ( ) U9 74HC74 ( ) U10 CD4006B ( ) U11 74HC86 ( ) U12 74HC4538 ( ) U13 16V8 or 18CV8 ( ) U14 16V8 or 18CV8 ( ) U15 27C64 labelled "STATE 2.00" ( ) U16 74HC574 ( ) U17 27C64 labelled "TX9600 1.0" ( ) U18 74HC574 ( ) U19 74HC14

( ) Using 3/4" #6 spacers and 7/8" 6-32 screws, install

the modem on the PK232 motherboard, spacing above the motherboard and using the two screw holes just vacated.

( ) Place the free end of the wire attached to SW1 to

pins 24 and 26 of P3 on the modem.

( ) Install the wire with the two-pin connectors as

follows: One end at JP2 terminal 5 of the PakMail daughterboard.

9600bps Modem Kit January 1993 Page 11 of 38

( ) U20 AD7523 ( ) U21 74HCT393 ( ) U22 TL084

Be sure all the ICs are properly seated, and that no pins are folded under a chip or hanging over the edge of a socket.

( )

Apply power verify that the PK232 signs on normally .

Page 12

NOTE: If the PK232 seems sluggish, or takes a long

TOP

time to reset, or never resets and signs one, check your power supply voltage to the PK232. The modem adds 50 mA or so of current drain, and marginal power supply (one rated at 500 mA, for example) will cause the system to exhibit this symptom. The modem is not at fault; replace the power supply before proceeding!

( ) Place a jumper across pins 1 and 2 of the PK232

"EXT MODEM" connector on the rear panel of the PK232.

( ) Preset R11 on the modem boar d to full CCW , then

1/8 turn CW.

( ) Preset R21 to mid-range.

PK232MBX (without daughterboard)

Internal Installation

The following directions apply to PK232s above serial number 45933 with the PakMail function installed on the motherboard. If your unit has a daughterboard card plugged into sockets on the motherboard labeled U2 and U4, refer to the “PK232 Internal Insallation” directions.

This section assumes you have the TAPR PK232 Modem Disconnect Header modification kit. If you do not, one may be obtained from T APR. If you prefer to not use the modem disconnect, refer to the “Generic Installations” section of the manual.

( ) Issue the following commands to the PK232:

HBAUD 9600 FULLDUP ON

These commands will set the HDLC data rate to 9600 bps and tell the PK232 to ignore the DCD LED.

( ) Note that the modem's DCD LED is off. ( ) Issue the command

ALTMODEM 1

and the DCD LED should illuminate on the modem board. This tells you that the modem is "hearing" and decoding its transmit data via the loopback connection.

( ) Issue a connect to yourself. This will check out

the receive decode portion of the modem. Note that the PTT LED will flash on the modem along with the "SEND" LED on the PK232 front panel.

You may restore normal operation to your PK232 by issuing the ALTMODEM 0 command to select the normal modem, and setting HBAUD to whatever data rate you normally use. Remember to reset FULLDUP OFF or your transmitter will gleefully step on other stations' signals!

In addition to the TAPR Modem Disconnect kit, you may wish to use the TAPR PK232MBX Installation kit, which contains prewired plug ‘n’ play harness and all hardware needed for installing the 9600 bps modem inside your PK232MBX. This kit is available from TAPR.

Modem Preparation

Perform the following steps to complete assembly of your modem prepared for internal PK232 installation.

U23

( ) Install the LM7805 voltage regulator at U23 on the

modem board. The regulator should lay flat

against the surface of the board. There is no need

to fasten the regulator with screws as the modem

draws very little current and the regulator will

not overheat.

P1 NOTE: The 5-pin right-angle male header will be

installed on the BOTTOM side of the modem PC board. ( ) Place the 5-pin right angle connector on the bottom

(solder) side of the modem PC board. It should

rest on the bottom surface of the board. The pins

from the connector should "point" towards the PC

board, not away from it. See illustration below.

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information.

When you have performed the interface, proceed to the section in this manual entitled FINAL

CHECKOUT.

Page 12 of 38 January 1993 9600bps Modem Kit

( ) Check the clipped leads from R1-R6 and C1-C9

and verify that they are flush, or nearly flush, with

the PC board. Clip and reheat the connections as

necessary. This will ensure proper fit of the mating

connector , attached later. ( ) Solder the 5 pins of the connector to the top of the

PC board.

Page 13

Further Steps - All PK232MBX Installations

PIN 1

PIN 2

PIN 20

PIN 1

PIN 2

PIN 20

8 inches

Study the illustration below before mounting P3.

( ) Fabricate a 8" (20 cm) long single-wir e cable using

a two-pin header shell at one end and a stripped,

tinned wire at the other end.

( )

Cut the supplied 26-pin male header to a 20-pin header .

( ) Solder the header to the PC board so it occupies

pins 1 through 20 of P3. The short pins go into the PC board; the long pins stick up fr om the top of the PC board.

( ) Cut a 2-pin header from the remaining 6-pin

portion of the header used for P3.

( ) Solder this connector to pins 24 and 26 of location P3.

Jumpers

( ) Be sur e you have NO shunts installed at JP2, JP3,

JP4, or JP5.

Options

( ) The CLOCK option, if installed, must be disabled

by leaving JP2 open.

( ) The BIT REGENERA TOR option, if installed, must

be removed. This is done by simply removing ICs U1, U2 and U3 from their sockets.

PK232 Preparation

( ) Remove the case fr om the PK232 by removing the

shunt at one end and a stripped, tinned wire at

the other end.. ( ) Fabricate a 5-wir e cable 4" (10 cm) long using a 5-

pin connector shell using ribbon cable as follows:

Pin 1 Brown Pin 2 Red Pin 3 Orange Pin 4 Yellow Pin 5 Green

Modem Integration

( ) Ensure that JP4, JP5 and JP6 on the PK232MBX

motherboard are installed at the "B" positions for

each of these jumpers. ( ) Attach the 5-pin connector to P1, on the underside

of the modem. ( ) Using 3/4" #6 spacers and 7/8" 6-32 screws, install

the modem on the PK232 motherboard, spacing

above the motherboard and using the two screw

holes just vacated. ( ) Solder the free end of the 3.5" wir e to J13 pin 5.

six (6) screws that fasten it together.

( ) Place the shunt on the free end of the wir e soldered

( ) Fabricate a 3.5" (9 cm) long cable with a push-on

( ) If you have not already done so, fabricate, install

and checkout the TAPR PK232 Modem Disconnect kit.

to J13 pin 5 to pins 24 of P3 on the modem. ( ) Solder the free end of the 8" wire with the two-

pin shell shunt attached to J13 pin 2.

( ) Remove the two screws on the PK232

motherboard in the center (one at the rear edge between J7 and J8, the other near U38 and Q10 towards the front panel of the unit).

( ) Place two-pin shell end of the 8" wire just solder ed

to J13 pin 2 to JP6 on the modem. The single wire

in this connector shall connects to the pin of JP6

nearer the label "U22".

( ) Remove the jumper at JP-8.

( ) Solder the five (5) wires from the five-wire cable

NOTE: Skip to Modem Integration Using TAPR PK232MBX Installation Kit. If you are using the T APR PK232MBX INstallation kit.

Cabling - Not using the PK232MBX Installation Kit

( ) Fabricate an 8" (20 cm) long cable with a 20-pin

female IDC header at each end, such that pins 1 are tied together, pins 2 are tied together, etc., through pins 20.

9600bps Modem Kit January 1993 Page 13 of 38

fabricated above to the PK232MBX motherboard

as follows:

Brown JP4 end "A" Red JP5 end "A" Orange J13 pin 9 Yellow J13 pin 9 Green JP8 center pin

Proceed to

Page 14

Modem Integration Using TAPR PK232MBX

Installation Kit

( ) Remove any shunts on jumpers JP4, JP5 and JP6

on the PK232mbx motherboard.

( ) Attach the 5-pin connector labelled "P1" from the

wiring harness to P1, on the underside of the modem.

( ) Using the 3/4" #6 splacers and 7/8" 6-32 screws,

install the modem on the PK-232 motherboard, spacing above the motherboard and using the two screw holes vacated above.

( ) Plug the shell marked "#1" from the wiring

harness to J13 on the PK232MBX mother board.

( ) Plug the shell marked "#2" from the wiring

harness to JP4, JP5, and JP6 on the PK232MBX motherboard.

( ) Plug the shell marked "#3" from the wiring

harness to JP8 on the PK232MBX motherboard.

( ) Plug the shell marked "#4" from the wiring

harness to P3 pins 24 and 26 on the 9600 modem. The single wire in this connector goes to pin 26.

( ) Plug the shell marked "#5" from the wiring

harness to JP6 on the 9600 modem. The single wire connects to the pin on JP6 nearer the legend "U22".

Further Steps - all PK232MBX Installations

( )

Form the 20-pin cable into a "Z" shape as shown below .

Be sure all the ICs are properly seated, and that no pins are folded under a chip or hanging over the edge of a socket.

( )

Apply power verify that the PK232 signs on normally .

NOTE: If the PK232 seems sluggish, or takes a long time to reset, or never resets and signs one, check your power supply voltage to the PK232. The modem adds 50 mA or so of current drain, and marginal power supply (one rated at 500 mA, for example) will cause the system to exhibit this symptom. The modem is not at fault; replace the power supply before proceeding!

( ) Place a jumper across pins 1 and 2 of the

PK232Mbx "EXT MODEM" connector on the rear

panel of the PK232MBX. ( ) Preset R11 on the modem board to full CCW , then

1/8 turn CW. ( ) Preset R21 to mid-range. ( ) Issue the following commands to the PK232MBX:

( ) Insert one end into the modem header P3, with

pin 1 near the silkscreened dot on the board.

( ) Remove any jumpers fr om the Modem Disconnect

header P1.

( ) Insert the other end of the 20-pin cable into the

Modem Disconnect header, P1, with pin 1 near the silkscreen legend "P1".

Initial Checkout

Apply power to the modem and verify that +5 volts appears between U13 pin 20 and U13 pin 10.

HBAUD 9600 FULLDUP ON

These commands will set the HDLC data rate to 9600 bps and tell the PK232 to ignore the DCD LED.

( ) Note that the modem's DCD LED is off. ( ) Issue the command

ALTMODEM 1

and the DCD LED should illuminate on the modem board. This tells you that the modem is "hearing" and decoding its transmit data via the loopback connection.

Page 14 of 38 January 1993 9600bps Modem Kit

Page 15

( ) Issue a connect to yourself. This will check out

the receive decode portion of the modem. Note that the PTT LED will flash on the modem along with the "SEND" LED on the PK232 front panel.

You may restore normal operation to your PK232MBX by issuing the ALTMODEM 0 command to select the normal modem, and setting HBAUD to whatever data rate you normally use. Remember to reset FULLDUP OFF or your transmitter will gleefully step on other stations' signals!

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information.

When you have performed the interface, proceed to the section in this manual entitled FINAL

CHECKOUT.

AEA PK88

Mechanical

The modem will not easily fit inside the PK88. The heatsink for the PK88 voltage regulator is in the way and has to be trimmed. Crystal XT AL1 and capacitors C19, C36 and C39 must be laid down. Jumpers JP3 and JP7 may have to be trimmed. TAPR has not performed an internal installation. The following instructions are for an external installation.

The modem should be mounted in its own shielded metal cabinet with all leads properly bypassed for the RF environment it is expected to operate in. Shielded cable should be used to connect the modem to the TNC, and this cable should be as short as practical for reasons of electrical interference.

Electrical

The PK88 brings its external modem connections to otherwise unused pins of the RS-232C 25-pin serial port connector. There are a number of unused pins on this connector. After you make these modifications, you will need to use a specially wired RS-232C serial port connector with your PK88. But, you will be able to easily use your PK88 with external modems such as the TAPR 9600 bps and other modems.

RS-232C connector J1 comes wired from AEA as follows:

9600bps Modem Kit January 1993 Page 15 of 38

Pin Function 1 Frame Ground (PK88 chassis) 2 RS232 TXD (data in to PK88) 3 RS232 RXD (data out from PK88) 4 RS232 RTS (signal in to PK88) 5 RS232 CTS (signal out from PK88) 6 RS232 DSR (output, pulled to +10 inside PK88) 7 Signal Ground (PK88 signal) 8 RS232 DCD (output from PK88) 9 n/c 10 may be jumpered to pin 6 via

PK88 internal jumper JP9 11 n/c 12 n/c 13 TTL CLK - output from PK88 at

32x radio channel data rate 14* TTL DCD - input to PK88 from external modem 15* TTL RXD - input to PK88 from external modem 16* TTL TXD -output from PK88 to external modem 17 Ground, same as pin 7 18 n/c 19 n/c 20 n/c 21 n/c 22 n/c 23 frame ground 24 n/c 25 n/c

NOTE: The signals marked with an asterisk (*) are only enabled when the appropriate internal jumper is placed in the PK88, which simultaneously disables the internal modem.

Connector J1 will be modified to use the following pins: 12 Ground 13 TTL 32x clk from PK88 14* TTL DCD to PK88 15* TTL RXD to PK88 16* TTL TXD from PK88 18 TTL RTS from PK88 19 TTL RTS to PK88 internal modem 21 TTL RXD from internal modem 22 TTL DCD from internal modem 24 Switched +12v from PK88

After performing these modifications, the PK88 will require the following pins to be jumpered in the RS232C serial port cable connector to enable the internal modem for normal use:

Pin 14 to pin 22 (enables radio channel DCD) Pin 15 to pin 21 (enables radio channel RXD) Pin 18 to pin 19 (enables radio channel PTT)

Page 16

Finally, be absolutely certain that your RS-232C cable

B B B

A A A

Rear of PK88

B B B

A A A

"top" row

"bottom" row

"top" row

"bottom" row

doesn’t connect pins 13-16, 18, 19, 21, 22 or 25 (these are almost never used, and certainly not by PCs such as Amateurs use!).

( ) Construct the T APR 9600 bps Modem kit. Include

the internal LEDs and the voltage regulator, but

do not install the internal clock or bit regenerator options.

PK88 Preparation

( ) Remove power from the PK88. (This means to

physically disconnect the power supply from the jack on the PK88, not merely turning it off!)

( ) Remove the PK88 from its cabinet, and remove

the PC board from the cabinet base.

( ) Place all three JP4 jumpers toward rear edge of

PC board and center pins.

WAS:

NOW:

( ) On the bottom of the PK88 PC board add the

following wire jumpers:

JP4 center row pin “A” to J1 pin 21 (rxd from internal

modem)

JP4 top row pin “A” to J1 pin 22 (dcd from internal

modem) JP4 bottom row pin “A” to pin “B” J1 pin 7 to J1 pin 12 (gnd) Junction of R10/R11 to J1 pin 19(rts to internal modem) IC12 pin 17 to J1 pin 18 (rts from PK88) Plus side of C2 to J1 pin 24 (switched +12v from PK88)

( ) Do not install jumpers at JP2, JP3, JP4, or JP5 of

the 9600 bps modem.

( ) Wire an RS-232C cable to your computer and

make sure the PK88 end of the cable is wired as follows:

PK88 RS-232C 9600 bps Modem 26-pin header pins 1-8, pin 10, pin 17, and pin 23 as before.

12 Ground 15 13 32x Clk —> 11 14 DCD <— 1 15 RXD <— 17 16 TXD —> 19 18 RTS —> 5 19 RTS <— 6 21 RXD —> 18 22 DCD —> 2 24 +12v 26

( ) Set the PK88 to FULLDUP ON and HBAUD 9600. ( ) Place a jumper at modem P1 pins 1 and 2. ( ) The DCD LED should illuminate. If it does not,

troubleshoot the modem and cabling.

( ) Connect to yourself. ( ) Note that the PTT LED on the modem flashes

when you connect.

( ) Disconnect.

( ) On the bottom of the PK88 PC board, cut the trace

leading away from the junction of R10/R1 1. ( ) Reassemble the PK88. ( ) Wire an RS-232C cable to your computer and

make sure the PK88 end of the cable is wired as

follows:

Pins 1-8, 10, 17 and 23 as before. Pin 18 jumpered to pin 19. Pin 15 jumpered to pin 21.

( ) Apply power to the PK88 and verify that it works

Pin 14 jumpered to pin 22.

normally before proceeding. Include an on-the-

air test to verify the internal modem is functioning

properly.

Page 16 of 38 January 1993 9600bps Modem Kit

( ) Set FULLDUP OFF. Remember to short JP4 on the modem to enable the

PK88 internal modem. You must also reset HBAUD 1200 (or 300) to use the internal modem.

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information.

When you have performed the interface, proceed to the section in this manual entitled FINAL

CHECKOUT.

Page 17

AEA PCB-88

KA1BOY lent T APR his PCB-88 TNC to interface the TAPR 9600bps modem. The interface is very straightforward. The PCB88 includes a 26-pin modem disconnect header that is very similar to the one in a TNC-2

( ) Install the 26-pin cable, so that pin 1 of the modem

goes to pin 1 of the PCB-88 disconnect, pin 2 to pin2 2, etc.

( ) Install a jumper on the 9600 modem at JP6 labelled

TNC MODEM. This will enable the internal modem in the PCB-88.

PCB88 Mods

Please refer to the PCB88 component layout diagram located on page C-1 of the PCB-88 Operations Manual.

The PCB88 must be slighly modified to connect to the 9600 bps modem:

( ) Locate modem disconnect header J1 on the PCB88

PC board. This is the 26-pin male header near the

rear of the PC boar d.

( ) On the solder (bottom) side of the board, car efully

cut the following traces:

Jumper from J1 pin 1 to J1 pin 2 Jumper from J1 pin 5 to J1 pin 6 Jumper from J1 pin 17 to J1 pin 18

( ) On the component side of the board, temporarily

place push-on shunts across J1 pin 1 to 2, 5 to 6,

and 17 to 18.

( ) Verify the PCB-88 works as it did before the

modifications in this section.

( ) Verify the PCB-88 works as befor e.

( ) Installa loop-back jumper at 9600 modem P1 pins

1 and 2

( ) Remove the TNC MODEM jumper from the 9600

modem (JP6). This enables the 9600 modem.

( ) Set PCB-88 HBAUD to 9600 and FULLDUP to ON

( ) Connect to yourself and verify that the PTT and

DCD LEDs of the 9600 modem glow.

( ) Disconnect from yourself.

Final Steps

The 9600 modem and PCB-88 are now checked and verified. You must now locate a suitable mechanical location for the 9600 modem and install it. If this is inside your PC, beware of electrical noise that may be induced by board location and cable routing. If external, be sure to use a suitable shielded enclosure and cabling between the PCB-88 and the 9600 modem.

9600bps Modem Rev 1

( ) DO NOT INSTALL the 5-volt regulator IC U23.

( ) DO NOT INSTALL the internal clock option

( ) DO NOT INSTALL the bit regenerator option.

( ) Place a push-on shunt at JP3 (TNC 2).

( ) Be sure no jumper is installed at JP2 (INT CLK),

JP4 or JP5.

( ) On the circuit side of the PC board, carefully cut

the trace between P2 pin 11 and P2 pin 12.

( ) Install a 26-pin male header at P3.

Modem Checkout

( ) Fabricate a 26-pin cable to tie between the PCB-88

modem disconnect and the 26-pin male header

on the 9600 bps modem.

You will next have to interface the unit to your radio, modify the radio as necessary, and set the R11 compensation and R21 output level for the correct transmitter deviation.

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information.

When you have performed the interface, proceed to the section in this manual entitled FINAL

CHECKOUT.

Enjoy 9600 baud operation with your PCB-88.

9600bps Modem Kit January 1993 Page 17 of 38

Page 18

DRSI PC*PA

PC*PA Interface

The information presented is specific to the Type 1 PC*PA (port 0 fixed at 1200 bps with internal modem, port 1 set up for external modem). Other styles of the PC*PA may vary, so double check your unit before proceeding!

PC*PA Preparation

The external modem port must be set up for TTL interface levels. Information to do this is included in the Hardware Reference Manual provided with the PC*PA. Please read that section of your manual before proceeding with the following steps.

1) If you have a very early PC*PA, you will find the RS232 level translator chip is U9 (MC145406). If you don’t have this configuration, skip to step 2.

NOTE! This information for the earlier units is based on schematic diagram analysis only!

( ) Remove your PC*PA from your computer. ( ) Locate U9 (MC145406) and remove it. ( ) Prepar e a 16-pin header , jumpering pins 2-15, 3-14,

4-13, 5-12, 6-11, 7-10. Leave pins 1, 8, 9 and 16

unconnected.

__ __ 1| \/ |16 2|------|15 3|------|14 4|------|13 5|------|12 6|------|11 7|------|10 8|______|9

U9 header, top view

( ) Locate U13 (MC1488) and remove it. ( ) Prepare a 14-pin header, jumpering pins 2-3 and

8-9. Pins 1, 4-7 and 10-14 should remain unconnected.

__ __ 1| \/ |14 2|\ |13 3|/ |12 4| |11 5| |10 6| /|9 7|_____\|8

U13 header, top view

( ) Install the 14-pin header at U13. ( ) Locate U14 (MC1489) and remove it. ( ) Prepare a 14-pin header , jumpering pins 1-3, 8-10

and 1 1-13. Pins 2,4-7, 9, 12 and 14 should remain unconnected.

__ __ 1|\ \/ |14 2| | /|13 3|/ | |12 4| \|11 5| /|10 6| | |9 7|_____\|8

U14 header, top view

( ) Install the 14-pin header at U14. ( ) Place a jumper at JP3 on the PC*PA to power the

TAPR modem.

Modem Preparation Do NOT use the internal clock option or BitRegen option on the 9600 modem.

( ) On the cir cuit side of the PC*P A PC board, cut the

trace going from U9 pin 7 to U7 pin 28 (the 8530

SCC chip). ( ) On the circuit side of the PC*P A PC board, solder an

insulated jumper wire from U9 pin 7 to U7 pin 26. ( ) Place a jumper at JP2 on the PC*PA to power the

TAPR modem. ( ) Proceed to Modem Preparation below.

2) If you have a later PC*PA, you will find TTL <--> RS232 level conversion is handled by U13 (MC1488) and U14 (MC1489). If this is the case:

( ) Remove the PC*PA from your computer .

Page 18 of 38 January 1993 9600bps Modem Kit

( ) Install R20 and R24. ( ) Install the LEDs (D3, D4 and D5). ( ) P1 should be installed on the top of the PC board.

( ) P3 should be installed as a 26-pin male header on

the top of the PC board. ( ) Install U5. ( ) You must prepare a cable to connect between the

25-pin D connector on the PC*PA and P2 on the

modem. Use 8-conductor shielded cable and wire

it as follows:

Page 19

Function DB-25P 26-pin Header

Shield 1 and shell Ground 1 15, 25 TXDB 2 19 RXDB 3 17 /RTSB 4 5 /CTSB 5 5 Ground 7 15, 25 /DCDB 8 1 +12VDC 11 26 32XCLK 15 11

TNC 1 Internal Installation

TNC 1 Preparation

Perform the following modifications to your TNC 1: ( ) Solder a jumper wir e across R79 (680 ohm) located

near modem disconnect J5. If your TNC 1 already has a modem disconnect header

installed at J5: ( ) Remove any jumpers placed at modem disconnect

header J5.

( ) Install the PC*PA in your computer and connect

the modem to it via the cable just prepared.

( ) Apply power to the computer and verify that +5

volts appears between modem IC socket U13 pin 20 and U13 pin 10.

( ) Remove power from the computer and install the

ICs indicated beginning on the bottom of page 29 of the T APR manual.

( ) Ensure there is NOT a jumper placed at JP2, JP3,

JP4, JP5 or JP6 on the modem.

( ) Power up your computer and use the CONFIG22

utility supplied by DRSI to set Port 1 HBAUD to 9600 bps (HBAUD 5) and set DUPLEX ON (DUPLEX 1). Refer to the DRSI documentation for details on this.

( ) Place a jumper across pins 1 and 2 of modem

connector P1.

( ) Preset R11 on the modem boar d to full CCW , then

1/8 turn CW.

( ) Preset R21 to mid-range. ( ) The modem’s DCD LED should illuminate. If it

does not, troubleshoot the modem and cabling.

( ) Connect to yourself on Port 1. Note that the PTT

LED flashes on the modem. ( ) Disconnect. Preliminary checkout is done. The 9600 bps modem

should be installed in a well-shielded cabinet and use a minimum length shielded cable between the PC*P A and modem.

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information. When you have performed the interface, proceed to the section in this manual entitled FINAL CHECKOUT.

9600bps Modem Kit January 1993 Page 19 of 38

( ) Remove extractor “ears” from J5 if present. If your TNC 1 has no modem disconnect header

installed at J5: ( ) Install the 20-pin male header provided with the

modem kit at J5.

( ) Cut any default traces tying modem disconnect

header pins together. These will usually be 1-2, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, and 19-20.

If you intend to mount the modem inside the TNC 1 case and plug it directly into J5: ( ) C3 and C5 are too tall and must be laid down.

You may have to replace them or extend their leads to accomplish this. Lay them towards power supply diodes D9-D12.

NOTE: The following step is only necessary if you intend to use the TNC 1 internal clock and not the clock option on the 9600 bps modem.

( ) Place jumper JP7 on the TNC 1 PC board across

the pin pair nearer C12 - the default is the pair farther from C12. This will run the 6809 CPU at twice normal speed (1.84 MHz). The 6809 CPU, 6522 VIA and the 6551 ACIA chips may need to be replaced with higher speed parts (“B” or -2 parts) for reliable operation at the higher speed.

Modem Preparation ( ) Install R20 and R24.

( ) Install the LEDs (D3, D4, and D5). ( ) P1 should be installed on the top of the PC board. ( ) If you are going to directly plug the modem into

J5 on the TNC 1, use a 20-pin female connector installed on the bottom of the modem PC board at P3.

( ) If you are going to use a 20-pin ribbon cable to

connect your modem to ease access to the LEDs and P1 radio connector, use a 20-pin male connector installed on the top of the modem PC board at P3.

Page 20

( ) Install U5.

Pin 13

U-17F

1 3 5 7 9 11 13 15 17 19

2 4 6 8 10 12 14 16 18 20

( ) Attach a wir e from modem P3 pin 26 to +12 volts

available at the TNC 1 wire wrap area.

PacComm Tiny-2

Thanks to Frank Anderson, W7ZTA, and Jeff Angus, WA6FWI, for the following:

Proceed with the “Generic Installation” checkout and IC installation procedures.

( ) Place a jumper at JP4 pins 1 and 2 ( ) Place a jumper at JP5. Checkout Information

The following assumes you are using TAPR/ HEATH/AEA firmware. (WA8DED firmware commands are in parentheses like this.)

( ) If you ar e using the TNC 1 HBAUD generator with

a double-speed CPU clock, select HBAUD 4800

(<ESC>H9600) for 9600 bps operation and

HBAUD 600 (<ESC>H1200)for 1200 bps

operation. (<ESC>@C1 to enable double speed

clock for WA8DED firmware.) ( ) If you are using the modem internal clock option,

place a jumper on the modem at JP3. HBAUD

(<ESC>H) will have no effect on the modem

operation if this is done. ( ) Place a jumper at modem P1 pins 1 and 2.

Referring to the figure below, make the following modifications to the Tiny-2:

( ) The DCD LED should illuminate. If it does not,

troubleshoot the modem and cabling. ( ) Set FULLDUP ON (<ESC>@D1). ( ) Connect to yourself. ( ) Note that the PTT LED on the modem flashes

when you connect. ( ) Disconnect. ( ) Set FULLDUP OFF (<ESC>@D0). Remember to short JP6 on the modem to enable the

TNC 1 internal modem. This will also restore HBAUD (<ESC>H) operation for the internal modem if you are using the modem clock option.

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information. When you have performed the interface, proceed to the section in this manual entitled FINAL CHECKOUT.

This is the solder side of the PacComm Tiny-2 Tnc disconnect header

Step:

1. cut the traces as indictaed by the ‘x’ marks. (9 places)

2. add jumper at ‘a’ between header pin 5 and line to U17.

3. Follow the instructions above for installation in a TNC 2.

Page 20 of 38 January 1993 9600bps Modem Kit

Page 21

Generic Installations

For installations other than the specific ones detailed above, refer to the following steps. You may wish to review the detailed information on other TNCs anyway, since much of what is outlined in those sections may apply to your particular system. Please let us know how you instal the modem in other units so we may expand the manual and share this information with others.

U23

If you will be obtaining +5 volts from your installation, you will not require U23. +5 volts will then need to be applied to P3 pin 23.

The modem will draw approximately 50 mA from the 5-volt source. If you will be providing +7 to +20 volts to the modem, then proceed with the installation of U23.

!!!!! IMPORTANT NOTE !!!!!

The programmable logic devices U13 and U14 are specifically programmed to support the switching requirements of the PK232, TNC 1, TNC 2 and clones thereof. If you are installing the modem in another TNC, contact the T APR office . These chips may need to be reprogrammed to properly operate in other units. We will work with you to get the programmable logic worked out and then add the logic patterns.

TNCs that probably won't work with the 9600 bps modem are those that use "software" HDLC. This includes Kantronics units in the KPC and KAM series, the GLB PK-1, and the PMP/Baycom and C64 software packages.

Install the following parts P1 NOTE: P1 is usually installed on the top of the PC

board with the pins facing away from the PC board. However, your specific installation's mechanical requirements may dictate another orientation. Determine the orientation required, then pr oceed.

( ) P1 5-pin

P3 may be installed as a 20 or 26 pin male header (usually on the top of the PC board), or as a 20 pin female header (usually on the bottom of the PC board).

( ) Install the LM7805 voltage regulator at U23 on the

modem board. The regulator should lay flat against the surface of the board. There is no need to fasten the regulator with screws as the modem draws very little current and the regulator will not overheat.

Initial Checkout

Apply power to the modem and verify that +5 volts appears between U13 pin 20 and U13 pin 10.

Clock Option ( ) U6 74HC4060

You should determine the requirements of your installation, then proceed. You may wish to review the specific unit installation directions, above, to help you decide option which is best for your modem.

( ) Install a 20- or 26-pin male or female header at

P3.

9600bps Modem Kit January 1993 Page 21 of 38

BitRegen Option ( ) U1 16V8 or 18CV8 ( ) U2 CD40105B ( ) U3 74HC14

Be sure all the ICs are properly seated, and that no pins are folded under a chip or hanging over the edge of a socket.

Page 22

( ) Place a jumper at JP2 (INT CLK) only if you

installed the clock option and you are not going to use the TNC's clock for the 9600 bps modem.

( ) Place a jumper at JP3 (TNC 2) if r equired by your

TNC. This will usually be needed if your TNC supplies a 16x clock (153.6 kHz for 9600 bps). If your TNC supplies a 32x clock (307.2 kHz for 9600 bps) then no jumper should be placed at JP3.

( ) Place a jumper at JP4 pins 1 and 2 (TNC 1) or pins

2 and 3 (TNC 2) if required by your TNC. This jumper is used to configure the request to send (RTS) line between your TNC's HDLC controller and the TNC's internal modem. This jumper is not used at all by the 9600 bps modem.

( ) Place a jumper at JP5 (TNC 1) if r equired by your

TNC. This jumper provides a physical short between P3 pins 7 and 8. It is r equir ed for a TNC

1. It will cause improper operation of a TNC 2 (it will short the CON and STA LEDs)! If in doubt, leave this jumper off! It has no effect on the operation of the 9600 bps modem.

( ) Ensur e no jumper is placed at JP6 (TNC MODEM),

or that any switch wired to JP6 is in the open position.

( ) Command your TNC to ignore DCD. This is the

FULLDUP ON command on TAPR units.

( ) Note that the modem's DCD LED is now on. This

tells you that the modem is "hearing" and decoding its transmit data via the loopback connection.

NOTE: Some TNCs will not issue any transmit data until they are commanded to attempt a connection, or to enter a "calibrate" mode. If the DCD LED does not glow, try the next step. If it still does not glow, you may need to troubleshoot the modem.

( ) Issue a connect to yourself. This will check out

the receive decode portion of the modem. Note that the PTT LED will flash on the modem.

You may restore normal operation to your TNC by issuing the command to select the normal modem (or placing a shunt at JP6 on the modem, or closing a switch wired to JP6), and setting the radio port data rate to whatever data rate you normally use (might be a software command, such as HBAUD, or a hardware switch, or automatic if you are using the internal clock option). Remember to reset FULLDUP OFF or your transmitter will gleefully step on other stations' signals!

( ) Apply power and verify that the TNC signs on

normally.

NOTE: If the TNC seems sluggish, or takes a long time to reset, or never resets and signs one, check your power supply voltage to the TNC. The modem adds 50 mA or so of current drain, and marginal power supply may cause the system to exhibit this symptom. The modem is not at fault; replace the power supply before proceeding!

( ) Place a jumper across pins 1 and 2 of modem

connector P1.

( ) Preset R11 on the modem boar d to full CCW , then

1/8 turn CW.

( ) Preset R21 to mid-range.

( ) Command your TNC to operate at 9600 bps (may

be a software command, or may be a switch on the TNC, or may be just placing a shunt at JP6 on the modem).

Consult the manual from Mike Curtis, WD6EHR, for general radio interfacing information.

When you have performed the interface, proceed to the section in this manual entitled FINAL

CHECKOUT.

Page 22 of 38 January 1993 9600bps Modem Kit

Page 23

FINAL CHECKOUT

( ) Remove the loopback jumper from the modem

and connect the modem to a radio.

( ) Set R21 for 3 kHz deviation of your transmitter

(you need a deviation meter for this!) If you lack a deviation meter, but have access to an oscilloscope (an AC voltmeter pr obably isn't good enough) you may adjust the deviation using the approximate technique in Alternate Deviation Setting Method, below.

( ) Get another station to send to you with his TNC

in CAL mode sending a "fixed tone." Have the remote station place his TNC in CAL mode, press <K> key to activate transmitter, press space bar to send a mark or space "tone". (T APR and PK232 TNCs do this. Kantronics TNCs don't, so another method must be used if the remote station uses a Kantronics unit).

NOTE: Unlike 1200 bps AFSK/FM packet, it is better to err slightly on the high side of transmitter deviation on a 9600 bps FSK link than to err on the low side! T oo much isn't good, either, but a value up to about 4 kHz will work quite well unless the distant receiver has a very narrow passband or the transmitting and receiving ends of the link are poorly netted.

HARDWARE

This section includes a detailed circuit theory explanation and details on the functions of all connector and jumper pinouts.

Detailed Circuit Description

The TAPR 9600 bps modem is a baseband modem (meaning it works at audio and not at RF) for use with standard FM radios to produce a direct RF FSK data link.

( ) Connect on oscilloscope or a speaker/amplifier

to the BER test point.

( ) With the other station sending, slowly rotate R11

for minimum popping sound. Decrease the applied signal (add attenuation in your receiver antenna line, reduce the remote station's transmit power, etc.) and adjust R11 until no further improvement is noted.

( ) If you can't get another station to send, preset R1 1

to 1/8 turn from full CCW and hope for the best :-) This setting is usually close to optimum for radios with 10.7 MHz/455 kHz IF lineups using a ceramic filter at the 455 kHz IF for most of the selectivity. This lineup includes most radios of the last 10 years or so.

Alternate Deviation Setting Method

( ) Connect the oscilloscope to the detector output

(not amplified audio) of a narrow-band FM receiver tuned to your transmitter's fr equency.

( ) Using a voice transmitter, send a full-deviation

signal (shout into the microphone, for example). Most radios have a deviation limiter set to about 5 kHz peak deviation.

( ) Note the peak-to-peak voltage on the oscilloscope

while receiving the signal from the pr eceding step.

( ) Unkey the voice transmitter and key the 9600 bps

transmitter.

( ) Adjust R21 for 60% of the peak-to-peak voltage

noted above.

Receiver Signal Processing Analog Processing Section

Incoming audio from the radio FM detector (usually a quadrature detector within an IC such as a Motorola MC3357, 3359 or 3362) is applied to buffer U5A via C7/R13. C7 is a 0.1 uF capacitor selected to allow low frequency components of the incoming signal to pass, while R13 presents a high input impedance and sets the DC bias for the rest of the analog portion of the receive system.

U5A is configured as a simple voltage follower with a very high input impedance and a low output impedance. This prevents loading of the radio receiver while providing a corr ect termination for the input of the following filter .

U5B, along with its associated resistors and capacitors, forms a three-stage butterworth filter with a cutoff frequency of about 6 kHz. R11 provides compensation for the higher frequency end of this range, allowing a "boost" for radios whose high audio frequency response is insufficient. The available boost is only a few dB, so it can't compensate for a truly dismal radio.

The output of U5B is passed to comparator U4A, which acts as a slicer and determines when a signal is above or below the center of the incoming signal amplitude range.

Tracking of drift of the incoming signal is accomplished by virtue of the incoming signal coupling capacitor , C7.

9600bps Modem Kit January 1993 Page 23 of 38

Page 24

The output from U4A will swing from near ground to the +5 VDC bus voltage via pull-up resistor R5.

ensures that the correct state of U19D is not caused by a lack of input signal. This is because the state machine's DCD function operates by looking for

Digital Processing Section

The incoming transitions from U4A are coupled to a two-stage synchronizer circuit located in programmable logic device U13. The synchronized data is then fed to flip-flop U7B as well as to State Machine U15 and U16.

U15 and U16, along with a 16x clock signal (153.6 kHz in the case of 9600 bps operation), synchronize the incoming data edges. The state machine has two outputs:

1) a recovered clock at the data rate, used to descramble the incoming data and optionally clock the data into an attached TNC or bit regenerator, and

2) a signal quality indicator which pulses low whenever an incoming data transition is out of limits compared to the received clock being

edges that are out of sync; it does not operate by looking for edges that are in sync. U12B therefore prevents false DCD indications that may be caused by a period of NO SIGNAL activity which might be caused by using either (a) a squelched radio (ugh!) or (b) a full-duplex r epeater's not-yet-timed-out carrier.

Transmitter Signal Processing Scrambler

Incoming TTL data is applied to flip-flop U9B, and clocked by the applied transmit clock. This latched incoming data is applied to shift register U10. This shift register, along with signal delay flip-flop U9A and exclusive-or gates U11A and U11B, provides a 17-stage polynomial multiplier to convert the incoming NRZI into a data format with higher lowfrequency components.

The data stream is taken from gate U11A.

generated by the state machine.

Transmit Raised-Cosine Generator

Descrambler

The clock signal latches incoming data from U13 to flip-flop U7B whose output level is now synchronized by the clock. Data is simultaneously clocked into shift register U9. This shift r egister, along with signal delay flip-flop U7A and exclusive-or gates U1 1C and U1 1D,

The data from the scrambler is applied to state machine U17, U18 and clocked by U21A. For every bit that is clocked into the state machine, counter U21A provides sixteen (16) states. These states are used to provide an output from U18 that does one of four things:

provides a 17-stage polynomial divider to extract the NRZI bit stream from the incoming data.

The output of the descrambler, de-glitched by R26/

1) If the last bit was a one, and the current bit is a one, the output from U18 is held at its maximum value.

C23, is fed to inverters U19F and U19E. U19F provides TTL level data to the attached TNC and/or bit regenerator. U19E is AC-coupled to BER test point TP2, where it may be used to drive an oscilloscope or speaker for setting a link up for best bit error rate performance.

DCD

The signal quality pulses from the state machine are buffered by U19C, then coupled via diode D6 to U19D, a schmitt trigger which, along with C24 and R25, implements a pulse stretcher. Any pulse from the state machine is remembered for several milliseconds. The time constant of this circuit, determined by R25/C24, has been chosen to provide a minimum delay when data is valid, but more importantly to minimize falsing when noise is being received.

The output from U19D is passed to U12B, a retriggerable one-shot. U12B will trigger on data edges from U7B only when U19D is in the correct state. In this manner, U19D gates U12B, while U12B

Page 24 of 38 January 1993 9600bps Modem Kit

2) If the last bit was a zero, and the current bit is a zero, the output from U18 is held at is minimum value.

3) If the last bit was a one, and the current bit is a zero, the output from, U18 is stepped down (in 16 steps) in a pattern corresponding to the descending edge of a raised-cosine.

4) If the last bit was a zero and the current bit is a one, the output from U18 is stepped up (in 16 steps) in a pattern corresponding to the ascending edge of a raised-cosine.

The encoded values from U18 are fed to a digital-toanalog converter (D/A), U20.

Transmit Analog Signal Processing

The "stairstep" output from U20 is level-shifted by U22C and filtered by U22D. The now continuous waveform from U22D is set to the desired level for correct modulation of the attached transmitter by U22B, whose gain is controlled by trimpot R21.

Page 25

The output from U22B is AC-coupled by C30, a 10 uF capacitor to allow for relatively low transmitter input impedances.

Transmit Watchdog Timer

To prevent a runaway TNC from clogging a radio channel, the PTT information is passed through a oneshot, U12A. This device is set for a few tens of seconds, to allow maximum length packets to be transmitted while preventing a stuck PTT command from jamming the radio channel. Transmitter keying is provided by power FET Q1, the familiar VN10KM.

LED Indicators

LEDs are provided to monitor +5V power (D4), PTT activation (D3) and DCD (D5).

Optional Bit Regenerator

DCD from an incoming signal is passed to programmable logic device (PLD) U1. U1 then applies a PTT command to the PTT watchdog via U13 and clocks in received data from the descrambler . The data is stored in first-in first-out (FIFO) buffer U2, a CD40105B. After eight (8) received clocks have accumulated, U1 begins clocking data out from U2 via a stable transmit clock (rather than the possiblyjittery receive clock from the state machine).

This process continues until DCD goes false. At this point, U1 continues to clock out the remaining data bits from U2 (this may be fr om 0 to 16, depending on the clock accuracy of the sending station and the bit regenerators modem).

TNC Interface Logic

The TNC interface is via a standard modem disconnect header P3. P3 uses the PacComm extensions to the T APR disconnect in order to provide a convenient means to apply power to the modem.

Programmable logic devices (PLDs) U13 and U14 handle all configuration requirements for T APR TNC 1 and TNC 2 or clones, AEA PK88 and PK232, and DRSI PC*PA. Special variations of these chips may be necessary for other TNCs. Contact TAPR for availability for your particular TNC.

P2 is provided to allow chaining another external modem to your TNC. This may be useful for adding a 1200 bps PSK modem as well as the 9600 bps modem for your Amateur satellite station, for example. Configuration is handled by jumpers JP2-JP6 described later in this section.

Radio Interface

The signals to and from the radio are bypassed for RF by R1-R3, R14 and C1-C6. The signals are available at 5-pin connector P1.

Optional Clock Oscillator

A 74HC4060 oscillator/divider IC with a 4.9152 MHz crystal provides normal clocking signals or 32x (307.2 kHz) or 16x (153.6 kHz) for the modem. U6 is the IC, and Y1, along with the associated resistors and capacitors, provides the feedback to ensure oscillation at the desired frequency.

The FIFO signals to U1 when it is empty, at which point U1 releases its PTT command. The release of PTT is delayed about 10 mSec by U3 and associated components to allow the distant TNC to finish fetching the incoming data before the bit regenerator releases local PTT. This prevents noise bursts from possibly confusing the distant TNC and causing it to lose the data just received.

At this point, the local PTT is released and the modem goes quiescent.

If, however , the modem is attached to a TNC and that TNC wishes to access the modem and its radio, the control logic in U13 will pass control to the TNC in preference to the regenerator.

This allows a network node, for example, to seize control of the channel. On the other hand, when the bit regenerator is active, the same DCD signal that enables the regenerator is also passed to the TNC, so it will normally defer its transmission.

The override function has been included for specific applications.

Jumper Functions

The following table lists the function of each jumper on the 9600 bps modem PC board. Pay careful attention when reading this section to determine interface requirements to various TNCs. Several of the jumpers have no effect at all on the operation of the 9600 bps modem but may have a significant effect on the operation of the attached TNC!

9600bps Modem Kit January 1993 Page 25 of 38

Page 26

Jumper Position Function

JP1 OPEN Disables DCD LED.

CLOSED Enables DCD LED.

JP2 OPEN Selects clock signals from the TNC for clocking the 9600 bps modem.

CLOSED The internal clock option is the modem clocking source.

JP3 OPEN Assumes the attached TNC uses a 32x clock.

CLOSED Assumes the attached TNC uses a 16x clock.

JP4 Selects RTS options on the attached TNC.

1&2 P3 pins 9 and 10 are shorted together (needed by TNC 1 and clones). 2&3 P3 pins 5 and 9 are connected together (needed by TNC 2s and clones).

JP5 OPEN Does nothing.

CLOSED Shorts P3 pins 7 and 8. This is necessary for the proper operation of a TNC 1

(or clone) internal modem when the 9600 bps modem is bypassed. This position may damage a TNC 2!

JP6 OPEN Selects the 9600 bps modem.

CLOSED The 9600 bps modem is bypassed and the TNC's internal modem, if any , is selected.

Radio Connector - P1

This 5-pin connector interfaces the 9600 bps modem to a radio. Note that this must be "flat response audio" and not pre-emphasized, de-emphasized or otherwise shaped. Transmitter audio injection to the radio is usually directly to the FM modulator . Receive audio from the radio is usually taken directly fr om the detector circuit. See the 9600 bps Radio Handbook by Mike Curtis, included with your 9600 bps modem kit, for further information on radio interfacing.

Pin Name Function

1 RXA Receive Audio input. The bandpass should extend from about 100 Hz to a minimum

of about 7200 Hz. Signal levels from about 100 millivolts to about two volts are acceptable. The actual range depends on the setting of R11. The input impedance is high, on the order of 100K ohms, AC-coupled.

2 TXA Transmit Audio output. The signal level here is adjustable by R21 from a few 10s of

millivolts to a couple of volts depending on the transmitter input impedance.

The output impedance is on the order of 1K ohm, AC-coupled. 3 COMMON This is power and audio ground. 4 COMMON This is power and audio ground. 5 PTT Transmit Push to talk output. This line goes to ground via about 100 ohms when

transmitting. It can withstand about 25 volts open circuit and can sink several

tens of milliamperes. It is not protected from inductive loads, such as r elay coils.

Modem Disconnect - P3

The modem disconnect is used to connect the 9600 bps modem to the attached TNC. It may be wired as a 20or 26-pin connector . If wired as a 20-pin connector , pins 21-26 are not used. Note that many signals available at the header are not used by the modem but are provided for use by the TNC. Signals that are absolutely necessary for modem operation are marked with an asterisk (like this*).

Pin Name Function

1* DCD Out Data Carrier Detect output from modem to TNC. A logic low indicates DCD. 2 DCD In Data Carrier Detect input from TNC's modem. This signal is passed to pin 1 when

the 9600 bps modem is not selected. 3 N/C Not connected. 4 N/C Not connected. 5* RTS In Request to Send input from TNC. A logic low tells the modem to transmit.

Page 26 of 38 January 1993 9600bps Modem Kit

Page 27

6 RTS Out Request to Send output to TNC's modem. When the 9600 bps modem is not selected,

pin 5's level is passed to this pin. 7 N/C Not used. Routed to JP5. 8 N/C Not used. Routed to JP5. 9 N/C Not used. Routed to JP4. 10 N/C Not used. Routed to JP4. 11 TXC Out Transmit Clock output to TNC. This square wave is at 32x or 16x the data rate

depending on the status of JP3. 12* TXC In Transmit Clock input from TNC. This signal is expected at 16x or 32x the data rate

depending on the status of JP3. If the TNC does not provide this clock, it may be

provided locally by the Clock Option. 13 RXC Out Receive Clock output to TNC. This is not used by the modem and is a 32x or 1x

clock depending on the state of JP3. 14 RXC In Receive Clock input from TNC. 15* GND Power and signal common. 16 N/C Not used. 17* RXD Out Receive Data from the 9600 bps modem. 18 RXD In Receive Data from the TNC's modem. This signal is routed to pin 17 when the

9600 bps modem is not selected. 19* TXD In Transmit Data from the TNC. 20 TXD Out Transmit Data to the TNC's modem. This pin is always shorted to pin 19. 21 N/C Not used. 22 N/C Not used. 23 +5V +5V power. This is an input and should only be used if modem regulator U23 is

not installed. Current drain is about 50 mA. 24 N/C Not used. 25 GND Power and signal common. 26* +12V +12V unregulated power in. This voltage should be in the range of +8 to +20 VDC

and capable of supplying at least 50 mA. This signal is not needed if regulated

+5 VDC is instead supplied to pin 23.

Secondary Modem Disconnect - P2

This header is pr ovided to enable chaining another modem, such as the TAPR 1200 bps PSK modem, to the same TNC that the 9600 bps modem is attached.

NOTE: In its default condition, all pin pairs of P2 are shorted, e.g., pin 1 to pin 2, pin 3 to pin 4, etc. If an external modem is attached, the default shorting traces on the bottom of the modem PC board must be cut. If any traces are cut, shorting jumpers must be installed at P2 if the additional modem is disconnected.

Pin Name Function 1* DCD In Data Carrier Detect output from 9600 bps modem. A logic low indicates DCD.

This signal must be passed to pin 2 when the attached external modem is not in use. 2* DCD Out Data Carrier Detect output from the attached external modem. This pin must reflect

the state of pin 1 when the external modem is not in use. 3 N/C Not connected. 4 N/C Not used. 5* RTS Out Request to Send input to the 9600 bps modem. The signal at this pin must reflect

pin 6 when the external modem is not in use. 6* RTS In Request to Send input fr om the TNC to the attached external modem. 7 N/C Not used. Shorted to pin 8. 8 N/C Not used. Shorted to pin 7. 9 N/C Not used. Shorted to pin 10. 10 N/C Not used. Shorted to pin 9.

9600bps Modem Kit January 1993 Page 27 of 38

Page 28

11* TXC Out Transmit Clock output to TNC. This square wave is at 32x or 16x the data rate.

It must be passed to pin 12 when the attached external modem is not in use. 12* TXC In Transmit Clock input from TNC. This signal is at 16x or 32x the data rate. 13* RXC Out Receive Clock output to TNC. This signal is at 32x or 1x the data rate.

It must be passed to pin 14 when the attached external modem is not in use. 14* RXC In Receive Clock input from TNC. 15* GND Power and signal common. 16 N/C Not used. 17* RXD In Receive Data from the 9600 bps modem to the TNC. This signal must be passed to

pin 18 when the attached external modem is not in use. 18* RXD Out Receive Data fr om the attached external modem. This pin must r eflect the state of

pin 17 when the attached external modem is not in use. 19* TXD In Transmit Data from the TNC. This pin should r emain shorted to pin 20 at all times. 20* TXD Out Transmit Data to the TNC's modem. This pin should always be shorted to pin 19.

ERRATA

Unfortunately, we have discovered a few errors in the board layout for the secondary connector. If you do not plan to use your modem with an external modem connected to P2, you can ignore these, but TAPR recommends that you make the following modifications before building your modem kit if you intend to use it with another modem in the future.

( ) On the top of the 9600 modem board, cut the traces

that ties P3 pin 1 to P2 pin 2.

( ) On the top of the 9600 modem board, cut the trace

that ties P3 pin 17 to P2 pin 18. This trace passes between RP2 pin 2 and 3 and is difficult to get to.

( ) On the bottom of the 9600 modem board, cut the

trace that ties P2 pin 1 to U14 pin 12.

( ) On the bottom of the 9600 modem board, cut the

trace that ties P2 pin 17 to U14 pin 19.

( ) On the bottom of the 9600 modem board, add a

jumper from U14 pin 12 to P2 pin 2

( ) On the bottom of the 9600 modem board, add a

jumper from U14 pin 19 to P2 pin 18.

( ) On the bottom of the 9600 modem board, add a

jumper from P3 pin 1 to P2 pin 1.

Example: Attaching a TAPR 1200 bps PSK Modem

If the above pin descriptions look confusing, this section will describe interfacing a T APR PSK modem to P2.

NOTE: The PacComm PSK Modem attaches in exactly the same manner as the T APR PSK modem.

( ) Build and test the PSK modem without the 9600

bps modem and verify that it is working as expected.

( ) Build and test the 9600 bps modem and verify that

it works as expected.

( ) On the bottom side of the 9600 bps modem PC

board, carefully cut the traces shorting P2 pins 1

and 2. ( ) Likewise, cut the trace shorting P2 pins 17 and 18. ( ) Install push-on jumpers at P2 pins 1 and 2 and at

P2 pins 17 and 18. ( ) Again verify the correct operation of the 9600 bps

modem. ( ) Remove both push-on jumpers at P2. ( ) Install the modem disconnect header fr om the PSK

modem to P2.

( ) On the bottom of the 9600 modem board, add a

jumper from P3 pin 17 to P2 pin 17.

That's all there is to it! Now , when you wish to operate 1200 bps PSK packet, you turn on the PSK modem, de-select the 9600 bps modem (short JP6) and operate as if the 9600 bps modem weren't installed. When you wish to operate 9600 bps, switch off the PSK modem and operate as if it weren't there. For normal operation of your TNC, switch off the PSK modem and de-select the 9600 bps modem.

Page 28 of 38 January 1993 9600bps Modem Kit

Page 29

TROUBLESHOOTING

This section of the manual will deal diagnosing and repairing your 9600 bps modem in case it does not operate properly.

Before you attempt to troubleshoot your modem, you should carefully read and understand the Detailed

Circuit Description section earlier in this manual. Equipment Needed

You will need an oscilloscope, preferably DC coupled and able to read waveform voltages on the order of 1 to 5 volts with 10% accuracy. Calibrated, triggered sweep is a plus (and probably necessary). Almost any oscilloscope made in the last 15 years will suffice. The highest frequency of interest is a few hundred kilohertz.

A DC voltmeter to verify the 5-volt regulator is also necessary. Any DVM will work, and an old VOM with better than 5% accuracy will substitute easily.

A replica of the transmit waveform from U22 pin 7 should appear at U5 pins 3, 1, 5, 7 and TP1 in that order. See "Waveform 1." The waveform may alter slightly as it passes through this filter , with the higher frequencies becoming attenuated. The DC level of the waveform will be at +5 VDC through the filter.

U4 pin 1 (data slicer output) should have a rectangular waveform of about 5 volts amplitude. Rise and fall times will be in the sub-microsecond range. This waveform is applied to U13 pin 19, delayed, and passed out U13 pin 15 to U7 pin 12 (descrambler input) and U16 pin 2 (state machine data input).

A 16x clock (153.2 kHz) should be present at U16 pin

11. Synchronized to the rising edge of this clock, the slicer data at U16 pin 2 should appear at U16 pin 19 and U15 pin 3. A 9600 Hz clock should appear at U16 pin 15, U7 pin 11 and U19 pin 1. An inverted version of this clock should appear at U19 pin 2, U7 pin 3 and U8 pin 3.

Checking It Out NOTE: If the signals aren't present as noted in this

section, refer to the next section for the expected signal path back to the source.

NOTE: CMOS levels means voltages that swing within 1/2 volt of GND and +5 VDC.

Verify the +5 volt regulator output! If this voltage is out of tolerance (+4.75 to +5.25 volts), find and fix the problem before proceeding!

A TNC is NOT necessary unless you are using the TNC for a power source or a clock source.

Set the CLOCK jumper as appropriate for the TNC you are using.

Verify that there is a 9600 Hz square wave present at U19 pin 4. See "W aveform 2" at the end of this section.

Adjust the deviation control R21 for an amplitude of 1 volt peak-to-peak at U22 pin 7. See "Waveform 1" at the end of this section. This should be a cleanlooking waveform with high frequency components of 4.8 kHz. If you see higher-frequency noise on the output (usually around 200 kHz), U22 is oscillating. This may be due to a bad op amp or some sort of feedback from your transmitter input.

Install a jumper at P1 pins 1 and 2. This will loop back the transmit audio signal to the receiver input.

Set control R11 full CCW.

9600bps Modem Kit January 1993 Page 29 of 38

Sliced data at U7 pin 12 should appear at U7 pin 9 synchronized to the rising edge of the clock at U7 pin 1 1.

Descrambled data out should appear at U11 pin 11 with "glitches" of not more than 150 nSec. The output, free of glitches, should appear at U19 pin 12 (receive data output). The receive data output should match the transmit data input at U9 pin 12, with a time delay and perhaps some jitter.

At this point, the modem is essentially functional. All that remains of its basic operation is the DCD, PTT and TNC interface circuitry.

DCD is derived from U15 pin 19, which will either be near 0 VDC or have regular pulses from near +5 VDC to near 0 VDC. (It will be near +5 VDC when no signal is being received.) This pattern will be inverted and appear at U19 pin 6. A peak detector at the output of U19 pin 6 drives U19 pin 9. The peak detector is also a filter and determines the "attack time" of the DCD circuit. It is designed to provide minimum falsing on noise. The output of U19 pin 8 appears at U12 pin 11. (U12 pin 12 looks for transitions from U7 pin 8 which will indicate that the modem is "hearing" something. This received activity is used to gate the DCD to ensure that DCD is not asserted because of complete silence at the modem input. Remember, the DCD portion of the State Machine is looking for erroneous data transitions -- a lack of incoming data will have no erroneous transitions!) U12 pin 10 will be near + 5 VDC and drive LED D5 ON assuming JP1 is intact. U12 pin 9 will be near 0 VDC. This is the DCD output signal.

Page 30

PTT is applied to U12 pin 3 as a signal near 0 VDC when the transmit function is activated. U12 pin 6 will go near +5 VDC, turning on Q1 and applying a ground to the PTT output at P1. U12 pin 7 will go near 0 VDC, turning on LED D3. A slowly rising voltage will appear at U12 pin 2. If the transmit key signal is applied to U12 pin 3 for too long, the voltage at U12 pin 2 will rise high enough to timeout U12, removing the PTT from the radio and extinguishing the PTT LED.

The TNC interface circuitry looks a bit complex but is really just a big switch. A written explanation would be long and confusing. The signals are plainly labelled on the schematic. The important points about the interface are:

you are using the TNC clock, or U14 pins 5 (16x clock) or 6 (32x clock) if using the internal clock option. By this time, I will assume you have the 9600 Hz clock at U19 pin 4...

No Transmit Waveform

Incoming data isn't needed here. Assuming the 9600 Hz clock is present at U19 pin 4, check for it at U9 pin 11, U9 pin 3 and U10 pin 3. See "Waveform 2".

Next, verify that data at CMOS levels appears at U11 pin 3, then at U17 pin 3.

Verify that 9600 Hz appears at U17 pin 5, 19,200 Hz at U17 pin 6, 38,400 Hz at U17 pin 7 and 76,800 Hz at U17 pin 8. Finally, check for 153.6 kHz at U17 pin 9 and U18 pin 11.

1) The modem requires a 16x or 32x clock from the TNC or internal clock option.

2) The TNC DCD signal comes in on P3 pin 2 and goes out on P3 pin 1. The 9600 modem passes this signal when it is not selected, and passes its own DCD signal out P3 pin 1 when it is selected. The TNC needs the DCD signal at P3 pin 1; the 9600 modem does not need the TNC signal at P3 pin 2.

3) The TNC R TS (transmit command) signal comes from P3 pin 5. The 9600 modem needs this signal. If the 9600 modem is deselected, it passes P2 pin 5 to P3 pin 6; if it is selected, it passes no signal to P3 pin 6.

4) The 9600 modem expects a 16x or 32x clock from P3 pin 12.

Once these signals are present, look for the waveforms labelled A, B, C and D in the transmit analog section. See "Waveform 1". A varying data pattern should be present at U17 pins 11-13 and 15-19, as well as at U18 pins 2 through 9 and pins 13 through 19, and finally at U20 pins 5 through 11. This pattern is stored in EPROM U17 and generated as a result of the clock signals from U21 and the data pattern from U11A.

No Data Slicer Output

Follow the analog signal from P1 pin 1 through U5A and U5B. Verify the DC level of the signal is near +5 VDC. The reference voltage at U4 pin 2 should likewise be +5 VDC, and the same value as the "center" of the signal voltage. The output of the slicer should go from nearly 0 VDC to +5 VDC.

No Receive Clock

The 16x signal at U16 pin 11 is essential. After this

5) RX Data from the TNC comes in at P3 pin 18. This signal is passed to P3 pin 17 if the 9600 modem is deselected; the 9600 decoded data is passed to this pin if the modem is selected.

6) Tx data comes from the TNC at P3 pin 19. This data is passed to P3 pin 20 as well as the 9600 modem at all times.

Where to Look for Missing Signals 9600 Hz Transmit Clock

If the 9600 Hz clock isn't present on U19 pin 4, trace it back to U13 pin 16, then U13 pin 8, then U21 pin 6. See "W aveform 2." If it is still not present, look for a 16x clock (153.6 kHz) at U21 pin 1, then U13 pin 13, then U21 pin 1 1 OR pin 13 (depends on whether your TNC/clock provides a 16x or 32x clock -- the signal at U21 pin 11 should be 1/2 the fr equency of the signal at U21 pin 13). If the clock is still not present (whew!), then U14 pin 16 and U13 pin 4 should be checked if

Page 30 of 38 January 1993 9600bps Modem Kit

signal is verified, check all connections between U15 and U16, and all other connections of U15. If U16 pin 19 does not follow U16 pin 2, U16 is probably bad. If it does and there is still no 9600 Hz output at U16 pin 15, then U15 is likely bad.

No Receive Descrambled Data

Assuming data at U7 pin 12 and clock at U7 pin 11, verify the clock signal at U19 pins 1 and 2, U7 pin 3 and U8 pin 3. If all is well, try substituting the parts in the descrambler (U7, U8, U11 and U19).

No DCD

If U12 pin 11 is pulled below +0.8 VDC and ther e ar e transitions at U12 pin 12, then if no DCD is present U12 is probably bad.

No PTT

Verify the inputs as described. If they are present and there is no output, U12 is likely bad.

Page 31

Waveform 1

= HI

= LO

104 µsec

+5 vdc

0 vdc

(A)HI = +2.4 VDC, LO = +2.0 VDC, waveform is

"stepped"

NOTES ON OPTIONS

Clock Option

Use the clock option if you are:

(1) using the modem as a stand alone bit regenerator,

(2) using the modem with a TNC 1 or TNC 2 or exact

clone at "ODD" data rates, or

(3) using the modem with a TNC 2 or other switch-

selected radio port data rate TNC and you desire to automatically select the 9600 bps data rate when the 9600 bps modem is selected via JP6.

Do not use the clock option if you are:

(1) using the modem with a PK88, PK232, DRSI

PC*PA or

(2) a TNC which cannot accept an external clock

signal.

(B) HI = +6.0 VDC, LO = +4.8 VDC, waveform is

"stepped"

"smooth"

(D)Waveform is variable amplitude up to about 1.5

V peak-peak

Waveform 2

Bit Regenerator Option

Use the bit regenerator only if you are using the modem as part of a full-duplex repeater.

If you use the bit regenerator option for full duplex with a node attacked, the associated TNC will override the bit regenerator when it asserts PTT.

9600bps Modem Kit January 1993 Page 31 of 38

Page 32

Page 32 of 38 January 1993 9600bps Modem Kit

Page 33

R34

U20 U21 U22

R32

R33

+ +

C28 C29 C30

C24

R25

U18 U19

TP3

C25

R26

R27

C23

C27

C26

JP6

TNC

MODEM

R28 R29 R30 R31

R18 R19

R20

JP1

R24

R22

R23

U12

C21

R17

C22

PTTPWR

DCD

R21

U7 U8

U11

U10

R16

C20

C19

GND

TP2

R11

C17

C18

U16

U17

R12

R13 R14 R15

C11

U15

C13 C15 C16

R10

C12

C14

C10

U23

TP1

U14

U13

RP1

RP2

JP2

JP3

JP4

JP5

INT

CLK

TNC1 TNC2

9600bps Modem Kit January 1993 Page 33 of 38

TAPR TAPR,9600Bps,modem User guide

Specifications and Main Features

Frequently Asked Questions

User Manual