Hal Communications CT2100 User manual

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INSTRUCTION
MANUAL
HAL COMMUNICATIONS CORP.
BOX 365
URBANA, ILLINOIS 61801
QU ALITY COM M U NICATIONS EQ UIPM ENT

cT2100
COMMUNICATIONS
TERMINAL
Copyrlght, O 1981 by HAL Communications CoEp., Urbana, Illinois.
Printed in the United States of America. All rights reserved.
Contents of this publication may not be reproduced in any form withoub
Lhe written permission of the copyright owner.
February, 1984 Printing

CONTENTS:
CHAPTER
CHAPTER
CHAPTER 5. CONNECTIONS TO THE C'121
5.1 Normal Amateur Sta
5.2 Use of the RS232 D
5.3 Use of the RTTY L0
Controls.....r.
00
tion Connections . . . ., . .
ata Connections . . . . . . .,
0P Data Conneetlon . . . .' .
CT21OO COMMUNICATIONS TER}4INAL
INTRODUCTION . . . . . . . . . . . . . . . . . . . . .
1. UNPACKING AND INSPECTION . . . . . . . . . . . . . . .
2. SIMPLE HOOK-UP FOR THE EAGER AND IMPATIENT....
2.1 Connections to the CT2100
2.2 Presetting CT2100 Controls
2.3 Presetting the Transceiver
3.1 Connecting the CT2100 to
3.2 Reeeiving RTTY Signals
3.3 Low Tones or High Tones?
5
5
6
7
7
8
2.4 RTTY 0peration
?.5 Morse Operation aaaaaataaaaaaaaaa
CHAPTER 3. RECEIVING WITH THE CTzlOO Your Receiver aataa
3:l H:::l,ii!"i";"; ioa"' . : : : . : : : . : : . : :
CHAPTER 4. TRANSMITTING WITH THE CT21OO . . . . . . . . . . . . .
4.1 The KB2100 Keyboard . . . . . . . . . . . . . . .
4.2 Transmit Features . . . . . . . . . . . . . . . .
4.3 Use of the KSR Keyboard Entry Mode . . . . . . .
4.4 Use of the Sp1lt Screen Keyboard Mode . . . . . ,
4.5 Use of the HERE-IS Messages . . . . r . . . . ! .
4.6 Use of the MSG2100 Option . .' . . . . . . . . .
4.7 Special Consideratlons When Transmitting Morse .
4.8 Special Considerations When Transmitting Baudot .
I:?, ;Bi")"1,;"ffi:::ii:1":".*:": :":':'':':':u.ol'l'. :
4.11 Synchronous Idle Feature
4.12 The N0RM/L00P Transmit feature
4.13 The KOS Feature . . . . . . .'. . . r . . . . . .
10
10
11
14
17
1g
23
23
25
26
28
30
31
31
35
39
43
44
45
45
48
4g
51
52
52
53
54
55
57
OJ
66
5.4 Connection of an ASCII Printer
5.5 Connection of an Audio Tape Recorder . . . . . .
5.6 RTTY Tuning Oscilloscope Connections , . o . . .
5.7 Using a Television Set as a Monitor . . . . . . .
5.8 RF-Inducgd Problems . . . . . . . . . . . . . . .
5.9 Power Line Voltage and Frequency Changes . . . .
5.10 User Adjustments

CONTENTS:
CHAPTER 6.
Figure 'l .
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure B.
Figure 9.
Figure 10.
Figure 1 1.
Figure 12.
Figure 1 3.
TABLES:
TABLE 1.
TABLE 2.
TABLE 3.
TABLE 4.
CASE OF DIFFICULTY IN
o. t
6.2
o.J
Care and Feeding of
Typical Operational Your CT2100 Problems......
57
67
69
34
37
41
42
Repair Procedures . . . . . . . . . . . . 71
cHAprER 7. SPECTFTCATToNS . . . . . . . o . . . . . . . . . . . . 73
APPENDIX: PROGRAMMING AND INSTALLING THE MSG21OO . . . . . . . . BO
1. Specifying the Messages . . . . r . . . . . . . . B0
3'. #:::]ffi::;";: iii,'il3x,;,; . : : : : . : . : : E3
LIMITEDWARRANTY... . . . . O t.. . . ... .. . 85
ILLUSTRATIONS:
The CT2100 and KB2100
Simplified CT2100 Connections
The K82100 Keyboard
Morse ltieight Timing . . . . . . . . . . . . r . . . .
Connections to the CT2100
KOS Cireult Conneetions
Typicai Video Detector . . . . . . . . . . . . . . . . 56
Modified Vldeo Dectector . . . . . . . . . . . . . . . 56
RFI Reduction Techniques . . . . . . o . . . . . . . . 58
RFI Power Line Filters o . . . . . o . . . . o . . . . 60
Power Transformer Voltage Tap Connections . . . . . . 64
Power Frequency Change Jumpers . . . . . . ., . . . . 65
User Adjustable Controls . ., . . . . . . . o . . . . 67
Z
4
22
33
47
49
CONTINENTAL MORSE CODE . .
BAUDOTDATACODE.............
DISPLAY SYMBOLS FOR THE ASCII CODE . .
ASCII DATA CODE

CT21OO USER },IANUAL
INTRODU CTION
This manual describes the installation and operation of the FIAL CT2100
Communications Terminal. The fechnical details with schematic diag-
rams and user-repair procedures are described in a second publication,
the CT2100 Customer Maintenance Manual, available separately from HAL
Communieations Corp. or its designated dealers and representatives.
The features of the CT2100 have been designed for convenient and stra-
ight forward customer use; many features are self-explanatory from a
close examinatlon of the CT2100 front pane1, rear pane1, screen dis-
p1ay, ot' the keytops of the KB2100. However, like many sophisti.cated
electronic devices, there are some features and operator techniques
which you may not understand until you have read this manual. You
should plan to devote several hours to becoming familiar with your
cT21 00 .
However, there are many hobbyists, including this writer, who are
eager to try the new frgadgetff and lack the patience to plow through
chapters of technical talk without at least turning it on and trying
out something. Therefore, for the eager and impatient new owners, we
offer Chapter 2 SIMPLE HOOK-UP AND OPERATION FOR THE EAGER AND IMPA-
TIENT. After you have your CT2100 running as descr^ibed in Chapter 2,
plea-se then sit down and read the rest of this manual; yout1I find
the CT2100 will do a lot more things than can be outlined in the sim-
pllfied instruetions.

PAGE 2
Figure 1The CT2100 and K82100

PAGE 3
CHAPTER 1
UNPACKING AND INSPECTION
When you unpack your CT2100 and K82100, carefully lnspecL the shipping
earton and each cabinet for shlpping damage. Any evidence of shipping
damage should be immediately reported bo your supplying dealer or
shipping carrier. Be sure to save all packing materials if damage is
found bhe shipping carrier will want to inspect them for any insu-
ranee c1aim. Before discarding the packing materials check Ehat all
parts and accessories are accounted for. Check the accessories aga-
inst the following list. If any are found missing, double-eheck the
packing for loose parts and then notify eiLher your dealer or HAL Com-
munications Corp. of the shortage. Please specify the HAL part
number !
Accessory parts:
Accessories Packed With CT2100:
1 - 333-17250 AC Power Cord
16 310-35012 Phono Pin Plug
2 770-05001 0.5 Ampere slow-blow fuse
960-02051 Video eable
: B7o-02110 3:i'fl3.:?31 fil:*.ming Forms
Accessories Packed With K82100:
1 - 355-00755 7 Ft. Coil Keyboard Cable
ti**ti**t3*it***t$***lt*r(*****f **tin*ritt**nIiHtI**ri***n*tt*lt*lcltrS*Ilt***tinti*tt*ri*tt*
CAUTION !
It
A SERIOUS SHOCK HAZARD MAY EXIST I{HEN CONNECTING *
THE CT21OO TO OTHER EQUIfMENT. BEFORE I,IAKING ANY *
CONNECTIONS, BE SURE TO DISCONNECT THE CTz1OO AND *
OTHER EQUIPMENT FROI',I THE AC POWER LiNE. *
*
***l3l(**lt***it****n**n**tt***t(n***tilt*ri*.rittrililit3n*ri**nntT**xt6n*it*tinnitii***tt*n*
*
it
*
It
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PAGE 4
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CHAPTER 2
SIMPLE HOOK-UP AND OPERATION FOR THE EAGER AND IMPATIENT
PAGE 5
in this manu-
without read-
enough infor-
need to read
conveniences
Although there are many features of the CT2100 explained
31, you may wish to first trplug-it-intr and rrtry-it-outrr
ing the whole book. This section of the manua] presents
mation to start using the CT2100, but you will eventually
Chapters 3, 4, and 5 to take fu1I advantage of the many
included in your CT2100.
2.1 Conneetions t,o the CT2100
Refer to Figure 2 and not,ice the various connections you may make to
and from the CT2100. For a start, it is recommended that you make the
following connections at the present and leave the other conneetions
until aft,er you have read Chapters 3, 4, and 5. By all means, do not
connect the CT2100 or other slation equipment to the AC power source
until all other conneetions have been made.
1. Connect a good ground wire (1/4't shield braid preferred)
between the CT2100 cabinet, transceiver cabinet, and all
other station equipment eablnets.
2. Connecb a shielded audio cable between the reeeiver speaker
(audio) oufput and the CT2100 RCVR IN connector.
3. Connect a shielded audlo cable between an external speaker
(4 16 ohms) and the CT2100 AUDIO MONITOR connector.
(Optiona1, but recommended)
4. Connect a shielded audio cable between the transmitter mi-
crophone audio input and the CT2100 XMIT OUT conneetor.
Check your transmitter manual some lransmitters have +12
VDC on the mike input lead to run remote controls; use a 1
uF blocking eapacitor at the qike eonnector to prevent dam-
age to such a transmitter. -
5. Conneet a shielded audio cable between the transmitter
push-to-talk input and the CTz100 KOS SWITCH connector.
(Steps 4 and 5 may be combined in a 2 conductor frstereofl
cable wlth the transmilter end eonneeted to a microphone
eonnector; these steps are only necessary if you intend to
transmit during these preliminary tests).
6. Connect a coaxial eable between the video input of your mon-
itor and the CTz100 VIDE0 T0 MONITOR connector.
7. Connect the KB2i00 to the CT2100 with lhe coil cord supplied
(K82100 connector on CT2100),
8. Connect lhe CT2100, Video Monitor, and transceiver to the AC
power souree; do not turn-on the equipment yet. Use a
grounding type of AC out,let lf at all possible.

PAGE 6
2.2 Presetting CT2100 Controls
Before applying any power to the transceiver or the CT2100, preset the
controls as follows:
DATA:
DISPLAY:
TXlRX
CONTROL:
MODEM:
T/O:
MONITOR
Now, turn on the
top line of the
SPEED =
MODE =
PAGE CYCLE =
LINE CYCLE =
STATUS =
REV VIDEO =
USOS =
CLEAR SCRN =
HDX/FDX =
IDLE =
MAN TXIAUTO =
KOS =
RTTY/MODEM =
HIGH/LOhI =
NORM/REV =
AUTO =
RTTY SHIFT =
AUDI0/R5232 =
RCVE/TAPE =
N0RM/L00P =
OUTPUT/INPUT =
VOLUME =
as turned
iln
ltil
Itil
on (45 BAUD)
'' ( BAUDOT )
" (Page 2)
n (72/ line )
on (button in)
either position
on (button in)
as turned on
HDX (button in)
off (button out)
AUTO (button out)
off (button out)
RTTY (button in)
LOW (button out)
NORM (button in)
off (button out)
170 (right button in)
AUDIO (button in)
RCVE (button in)
NORM (button in)
INPUT (button out)
turn on CT2100 power;
set to n12 orelocktr
video monitor power and see
display: the following text on the
CT2100 V1.xP2
45 BD BAUDOT TX OFF USOS
This line is the status line and shows the CT2100 code and data rate
seleeted, condition of the TXIRX data outpub, and, in this case that
the Unshift 0n Space (USOS) feature has been selected. Also shown is
that page 2 (of 2 available) is being viewed. The rtvl .xrt shows the
production verslon of internal computer program (ttsoftwarerr) installed
in your unit.
If you use a monitor other than that supplied by HAL, you will prob-
ably need to adjust its horizontal and vertical size and position con-
trols. Be sure that you can view all four edges of the TV raster on
the screen.

PAGE 7
2.3 Presetting the Transeeiver Controls
Preset your transceiver controls as follows:
14.075 to 14.100
Antenna for above frequency range
LSB (lower sideband)
LSB
ON SLOW
2 kF.z voice bandwidth
l,laximum
Minimum
0ff
0n
Comfortable Level
FREQUENCY:
ANTENNA:
MODE:
PASSBAND TUNING:
RECEIVER AGC:
RCVR SELECTIVITY:
RCVR RF GAIN:
XMTR MIC. GAIN:
XMTR VOX:
POWER SWITCH:
RCVR AUDIO VOL:
You should now be able to tune signals on the receiver and hear them
either on the receiver speaker or through the external speaker at-
taehed to the CT2100. If you are using the external speaker, you can
use the MONITOR VOLUME eontrol on the CT2100 to contro] the volume.
2.4 RTTY Operation
Tune the receiver for a RTTY signal ("deedle-deedletr noise). Correct
RTTY tuning is shown with a vertical tuning bar on the upper left sec-
tion of the screen; tune for maximum bar length on both RTTY tones.
If you do NOT see the tuning bar, make sure that the STATUS button is
pushed in; if sti11 no tuning bar is seen, readjust the horizontal
width and position eontrols of the monitor. Properly tuned, the bar
will have a maximum length and not change appreciably as the signal
ehanges from mark to space. A1so, the MARK, +/+, and SPACE tuning
LEDs on the CT2100 front panel can be used for tuning; the +/+ LED
should stay on and the MARK and SPAQE LEDs flash alternately. You
should now have ftprinttt of the reeeived signal on the monitor screen.
If not, try other speeds, shifts, NORM/REV, etc.
To transmit RTTY, make sure that the XI{IT AUDIO GAIN conlrol is set to
minimum, turn the transmitter on with either its TX 0N control or use
the CT2100 MAN TX control (button in). Increase the XMIT AUDIO GAIN
until some RF output is obtained, tune the transmitter if necessary,
and set the XMIT AUDIO GAIN to the reeommended power leve1 for RTTY
(see your transceiver manual). After tuning and adjusting, turn off
the transmitter (with the transmitter switch or the CT2100 MAN TX
switch (to AUTO = button out) and turn on the CT2100 KOS feature (but-
ton in). Type the text to be transmitted on the CT2100 keyboard it
will be displayed in reverse video on the bottom portion of the
screen. When you are ready to transmil, type CTRL-7 (ho1d CTRL key
down and t,ap the tt|tt key). The KOS (Keyboard Operated Swj-tch) cireuit
of t,he CT2100 w111 turn the lransmitter on and the text will be
transmitted. This text was entered using KSR or bottom line entry

PAGE 8
mode; spllt screen is seleeted with CTRL-I. KSR and split screen
modes are discussed in sections 4.3 and 4.4 of this manual.
Programming and use of the HERE IS and IDENT messages is eovered in
sections 4.5 and 4.6. The transmitler wlll turn off automatieally
when all of the text has been transmitted and the transmit cursor is
on a blank new display 1ine. ALWAYS END A TRANSMISSI0N WITH THE NEW
LINE KEY. The transmit text may be stopped aL any time by typing
CTRL-7 again (status line on screen would go back to TX OFF indica-
tion). Word mode, word wrap-around, end-of-line sequences, KOS, IDLE'
and many other features are discussed in detail in Chapter 4.
2.5 Morse Operation
To use the CT2100 for Morse eode reception, press and release the
MORSE button in the DATA MODE fleld of the CT2100 front pane1.
Leave the transceiver mode in LSB for the present and tune to a Morse
code signal. When the receiver ls eorreetly tuned, the audio beat
note w111 be approximately 800 Hz and the CW LED on the CT2100 front
panel will flash in sync wlth the key-down conditlon of the slgnal.
You may monitor the code as processed by the CT2100 by switching the
MONITOR switch to OUTPUT (button in); the Morse decoding eircuit
drives the internal sidetone oscillator. Since the sidetone oscilla-
tor is frequency synthesized to 800 Hz, you may compare its frequeney
to that of ihe received signal by switching between MONITOR INPUT and
OUTPUT and adjust the receiver tuning until they match. This techni-
que gives a very accurate way of oplimizing t,he tuning. The Morse re-
eeive section of the CT2100 ls more amplitude sensitive than the RTTY
section; set the receiver audio gain so that the audio output from
the CT2100 MONIT0R OUTPUT is similar for MONITOR INPUT and OUTPUT
switch settings. Oecasionally, you may find that the Morse receive
seetion appears to have tf locked-uptt no longer displays received
characters. This is usually due to reception of a long time-duration
CW carrier; the autotrack circuit of the CT2100 is looking for some
very very slow Morse eode ! Eventually, *the autotrack circuit will ad-
just upward in speed and resume copying the reOelved signal. However'
the autotrack program can be reset for moderate speeds by pressing and
releasing the MORSE DATA MODE switch; each press resets the receive
circuitry. You will then see several ttTrt and rrEtr characters as the
autotrack program adjusts to the received signalrs speed. Correct
copy should resume within 1 to 10 characters after resetting the MORSE
button if the signal 1s correctly tuned.

PAGE 9
To transmit Morse code, first determine if your transmi,tter has a po-
sibive or negative voltage keying circuit. Next, connect a shielded
cable between the appropriate CT2100 CW KEY jack (POS or NEG) and the
CW KEY connection on the transceiver. Make sure that the KOS switch
of the CT2100 is off (button out) and the MAN TXIAUTO is in AUT0 posi-
tion (button out). Now, s€lect CW mode on the transceiver. Tune the
transmifter and set the CW leve1 if necessary using the K82100 BRK
key; this key gives key-down condition for as long as you hold 1t
down in Morse mode. Now, transmlt Morse code in the same manner as
explained above for RTTY, using CTRL-7 to turn the transmibted data on
or off.
Now that the basic operations of the CT2i00 have
back and read the rest of this manual. been explored, sit

PACE iO
CHAPTER 3
RECEIVING I'IITH THE CT21OO
3.1 Connecting the CT2100 to Your Receiver
Conneeting the CT2100 to your reeeiver ean be extremely simple just
hook a cable between the receiver audio output (external speaker or
phone patch output jacks) and the TTRCVR IN'r connector on the CT2100
rear panel. Most recelvers can be connected with a standard
'rhi gh-f idelityrr phono-to-phono cable , avai lab1e aL all '!HI-FIrr shops
(some receiver external speaker jacks may require an adapter, so check
out your receiver before you buy the cable). 0r, if you like to make
cables, use the phono plugs supplied in the CT2100 accessories. By
all means, use shielded cables this will reduce the chances of RFI
from the linear when you start transmitting! The CT2100 has been de-
signed to work well direcLly from the low-impedance speaker output,
but may work even better if a 500-600 ohm audio line output is avail-
ab1e. Few modern receivers include this option, but a speaker-to-line
transformer can be lnserted in the audio line if desired. If you cho-
ose to add the line transformer, pick one that will handle at least 1
to 2 Watts of audio most receivers are capable of producing enough
audio output to destroy one of those little 1/4 or 1/2 Watt rrtransis-
tor speclalstt ! Refer to Flgure 2 in the previous chapter for these
simple CT2100 conneetions; fuI1 connections are found in Figure 5 in
Chapter 5.
If you have an external monitor speaker for your receiver, you may
wish to take advantage of the built-in CT2100 audio monitor amplifler
system. To use this feature, hook the TTRCVR INtt conneetor of the
CT2100 to the reeeiver external speaker jack and plug the external
speaker itself into the "AUDIO MONITOR!| jack on the CT2100. A 2 Watt
audio amplifier in the CT2100 will now drive your external speaker (as
well as a sma1I internal monitor speaker). This internal monitor can
be switched wlth the "MONITOR INPUT/ OUTPUTil switch on the CT2100
front panel (b1ue button, lower right corner). With the button pushed
out (INPUT), the monitor lets you listen to the audi.o signal from your
recei ver , eontrolled by the front panel IrMONITOR VOLUMETT control .
Wit,h the button pushed in (OUTPUT), you can listen to your transmitted
RTTY tones or to the Morse sidetone output.
Even though we are just thinking about receiving at the present, this
ls a good time to put in a good ground between the receiver and
CT2100. Use a short, 1ow-inductance wire, preferably a 1/4n or wider
piece of shield braid. Make the ground lead as short as convenient,
direct from the CT2100 ground terminal to the receiver (or tran-
sceiver) ground terminal. Again, this is most important for
transmitter RFI protection, but it may also prevent receive RFI prob-
l-ems. By all means, USE GROUNDING TYPE AC OUTLETS this is a safety
measure that does not replace the need for a good RF ground.

PAGE 11
Now, connect the CT2100 to the video monitor with the coaxial cable
provided. Connect between the CT2100 "VIDEO T0 MONITORf' output and
the TV monitor "VIDEO INPUT" eonnector. You may find that your video
monitor requires an adapter between the UHF cable eonnection and the
monitor video input. You may also wish to hook an RF ground lead
between the monitor and CT2100.
Fina1ly, plug-in the AC power to the receiver, CT2100, and monitor and
turn-on the power switches to each. Proper settings for the CT2100
front panel switches will be discussed in the next sectj.on.
3.2 Receiving RTTY Signals
As a first step, preset the CT2100 front panel switches as follows:
DATA:
DISPLAY:
TXlRX
CONTROL:
MODEM:
r/o:
MONITOR:
SPEED =
MODE =
PAGE CYCLE =
LINE CYCLE =
CLEAR SCRN =
STATUS =
REV VIDEO =
USOS =
HDX/FDX =
IDLE =
MAN TXIAUTO =
KOS =
RTTY/MODEM =
HIGH/LO1,il =
NORM/REV =
AUTO =
SHIFT =
AUDI0/R5232 =
RCVE/TAPE =
N0RM/L00P =
OUTPUT/trNPUT =
VOLUME =
as turned on
BAUDOT (push in and release)
as turned on no change for now
ll ll rl ll tl lt tl
illlItIttllllt
on button in
off button out
on button in
HDX bublcn in
off button out
AUT0 button out
off button out
RTTY button in
LOW button out
N0RM button in
off button out
850 left-hand button in
AUDI0- button in
RCVE button in
NORM button in
INPUT- bqtton out
n 12 o I clockrr knob position
You should now see the following text on your TV monitor screen:
45 BD BAUDOT TX OFF USOS PZ CT2i00 Vl.x
This is the status line that indicates some of the terminal operating
conditions. The "45 BD BAUDOT'| indicales that Baudot RTTY mode has
been selected with a data rate ("speed") of 45 baud (60 wpm). The frTX
OFFrr shows that the transmitter data output has been turned off and
that text will not be transmltted. rrUSOS'r shows that the Baudot Un-
Shift-On-Space feature has been selected. rrP2tr shows that page 2, the
normal new text entry page is presently displayed. rrCT2100 V1 . xrr
icienti f ies the version of the computer program inst,alled in your
CT2100. (The ttxtt will be another number, such as "1 ,2,3, etcrt. )
If all of these indicators are as described, your CT21C0 i.s function-

PAGE 12
ing properly; 1f not, re-check your front panel switch settings. You
may now wish to try the LINE CYCLE switch note how the size of the
characters in the status line change when you switch between the 72
character-per-line mode and the 36 character-per-Iine mode. Select
the 72 character mode and momentarily push the PAGE CYCLE button
note how fhe page number changes from P2 to P1 and back to PZ on the
next button press. Switch to 36 character mode and note that now
there are four pages that can be selected. It is important to re-
member that new reeeived text (and keyboard typed text) ALWAYS appears
on the HIGH numbered page page 2 in 72 character line mode and page
4 ln 36 character line mode. When you are familiar with these fea-
tures, try the reverse video button interesting? There are many
display combinations you ean select with these three eonlrols. Now,
return the display to 72 character 1ines, page 2, and normal video.
(Switehing line length and video polarity is a good test of your moni-
tor a high-quality monitor will not require much lf any readjustment
when making these ehanges. )
Now, preset your reeeiver for the followlng conditions:
FREQUENCY:
ANTENNA:
MODE:
PASSBAND TUNINC:
AGC:
SELECTIVITY:
RF GAIN:
AUDIO GAIN:
14 .075 to 14 . '100 MHz
Adequate to recelve signals in above range
LSB (lower sideband)
LSB
ON SLOW
2 RHz normal SSB voiee bandwidth
Maximum
Comfortable listening 1evel see
following discussion.
If you have used the internal monitor amplifier of the CT2100, you
should set the receiver audio gain for a comfortable listening 1eveI
out of the external speaker.
If your reeeiver has an internal crystal callbrator, turn it on and
tune the receiver to it so that you get a 1 - 3 kldz audi.o beat note;
if you do not have a crystal calibrator, tune the frequency until you
get a beat note on a received carrier signal. There are four dlffer-
ent types of tuning indicators you may use on the CT2100:

/Al.l. I <
. rrv! t J
The tuning bar in the left vertical margin on the screen
The i,IARK, SPACE, and +/+ LEDs on the front panel
Audio tone comparison between the reeeived tone and the
internal transmit tones of the CT2100
A crossed-elIipse indication on an exLernal X-Y oscilloseope
(connecLed to the SCOPE MARK and SPACE rear panel connec-
tors )
Iiile will experiment with the first three bechniques at this time; the
external scope can be tried at a later time (see Chapter 5).
Tune your receiver frequency and notice that, ES the beat note fre-
quency changes, so does the length of the tunlng bar on the sereen;
also, the MARK and SPACE LEDs will alternately turn on as you tune
through thelr filters. You will need to tune s1ow1y and carefully
since the mark and space filters differ in frequency by only 850 Hz.
Note that the lower frequency audio tone (at 1275 Hz) turns on the
MARK light and peaks the tuning bar; the higher frequency tone (2125
Hz) turns on the SPACE light and gives another peak on the tuning bar.
The +/+ LED should be on for both mark and space conditi-ons.
Therefore, a correctly tuned RTTY signal will be indicated by alter-
nate fliekering of the MARK and SPACE LEDs, constant light on the +/+
LED, and by a tuning bar whose length changes 11ttle between mark and
space conditions.
Now, set the receiver tuning as accurately as you can to the MARK eon-
dition (MARK 1lght oo, tuning bar peak). Use the MONITOR INPUT/OUTPUT
switch to seleel OUTPUT (button in). The tone you hear is the
crystal-sythesized AFSK output tone from the CT2100; it should close-
1y match the frequency of your receiver beat note. Switch the
INPUT/0UTPUT button back and forth and compare the tone frequencies
you hear. It may be neeessary to slightly adjust the receiver and
monitor volume controls so that so that the INPUT and OUTPUT volume
levels match this adjustment of the r6ceive -volume is the correct
setting. (The OVLD LED should not be on since it indicates an exces-
sive reeeiver volume control setting. ) You can actually tune the re-
ceiver so that itrs beat note matches that of the CT2100 AFSK tone.
This teehnlque will assure you of true transceive operalion if used
carefully (assuming your transceiverts RF circuits are adjusted for
true transceive frequency match). Try the same test with the receiver
tuned for the space tone.
Next, turn-off the reeeiver calibrator (or tune away from the carrier)
anci select 17A shift (170 SHIFT button in). Tune the recelver while
llstening through the monitor speaker (}4ONITOR set for INPUT button
out) until you flnd a moderately strong amateur RTTY signal (identi-
fied by the characteristie tfdeedle-deedlert tones). With careful tun-
ing you should be able lo tune so that the tuning bar is near fuIl
length anci the MARK and SPACE light flicker alternately. A1so, the
1.
2.
?
)o
4.

PAGE 1I+
+/+ LED should stay on and the received tones should mateh the CT2100
internal tones (switeh INPUT/OUTPUT back and forth). You should now
See understandable text on the screen. If you don I t, try the
NORM/REVERSE switch if this corrects the reception, double check
your receiver settings to be sure you really are receiving LSB and not
USB. If this doesntt give you good "pritrttt, try increasing the CT2100
speed, trying both NORM and REV polarities for each speed. Speeds are
changed with the INC (for increase) and DEC bultons; each press and
release will increment to the next speed up or down. If you hold the
button in, fhe CT2100 will continue changing speeds until it is re-
leased. The current speed is shown on the status line on the screen.
If you still eanft make sense out of the display, try the ASCII code
aL 110 baud, €ither polarity. If all the combinations of MODE, SPEED,
and NORM/REV fai1, tune to another station, you have probably tuned-ln
an encrypted signaMune around the 20 meter amateur band and get
used to tuning-in RTTY signals. Itts dlfficult at first, but becomes
much easier with some practice !
If you have a general coverage recelver, you may now wish to try re-
ceiving short-wave press RTTY signals. Commereial press RTTY stations
can often be found on frequencies aroundt 5.2 MHz, 5.4 MHz, 5.8 MHz,
6.8 MHz, 7.5 MHz, 7.8 MHz, 8.0 MHz, 9.0 MHz, 9.4 MHz, 9.8 MHz, 10.2
MHz, 10.5 MHz, 10.8 MHz, 11.1 MHz, 11.5 MHz, 12.2 MHz, 13.5 MHz, 14.5
MHz, 14.9 MHz, 15 .5 MHz, 15 .9 MHz 16 .2 MHz, 16 .4 MHz, 17 .3 l4[z, 1T .5
MHz, 18 .2 MHz, 18 .4 MHz, 18 .7 MHz, and 19 .0 to 20 .5 MHz ( plus
others!). Commercial .RTTY stations will operate with either 850 or
425 Hz shift and may have speeds of 45 (60 wpm), 50 (67 wpm) , 57 (75
wpm), or 74 (100 wpm) baud, Baudot eode. The signals may be of either
signal polarity, so try both NORM and REV eonditlons. There may be a
few commercial press stations operating at 110 baud ASCII, also.
Tuning these commercial stations will require some patience due to the
wide variety of shifts, speeds, and polarities used.
The receive non-overprint feature will automatically place charaeters
on the next line of the screen if more than TZ (or 36) characters are
received between line feed characters. The word wrap-around feature
prevents the splitting in such cases, transfering the entire last word
to the next line. To further prevent overprint, the reeeive section
ignores all received carriage return (CR) characters and always exe-
cutes a carriage return and line feed (LF) whenever a LF character is
recei ved.
3.3 Low Tones or High Tones?
So far we have only used one
eombinations. You may wish
push the HIGH/LOW button in.
audio tones) are rea11y
used since the early days of
of the four possible CT2100 demodulator
to switch to the RTTY I'high-tonerr option
The ithigh tonest' (for higher-frequeney
the traditional standard U.S. RTTY tones,
amateur RTTY. The ttlow lonesrr are the

PAGE 15
IARU international standard are used extensively in most other coun-
tries of the world. When receiving (or transmitting) on the HF bands
(3-30 MHz), €ither set of tones will work sj.nce you tune the receiver
to produce the desired beat note frequency. However, when AFSK modu-
laiion is added to an FM or AM signal, you musl be prepared to reeeive
the same tone frequencies as those used by the transmitting station
(the AM or FM receiver does not use a BFO to produce the audio tone).
In the United States, the long-standing VHF AFSK tone standard has
been to use the 'rhigh tonestt (2125 Hz mark and 2295, 255A, or 2975 Hz
spaee); you must use a high-tone demodulator to be compatible ! In
Europe, in particular, the reverse standard is developing the IARU
'fIow tonen (1275 Hz mark and 1445, 1700, or 2125 Hz space) is the
standard to be observed. The two system are basically incompatible
for VHF AFSK operalion ! Due to 1ow-pass filter parameters, use of
data rates greater than 150 BAUD is not recommended when rrhighrr or
rtlow'r tone demodulator combinations are used; the MODEM TONES should
be used for higher data rates as explained in Section 3.4.
Each tone set has ils advantages and disadvantages the CT2100 lets
you choose the optimum combination for your station. Some of the eon-
siderations for each tone set are as follows:
HIGH TONES (Mark = 2125 Hz, Spaee = 2295,2550, or 2975 Hz):
Advantages:
1. High tones are the U.S. VHF AFSK standard their use
is required for compatibility when operating VHF AFSK in
the U.S. A hlgh tone demodulator may be used for both
VHF and HF use in the United States.
2. When high tones are used on HF, using tones into a LSB
transmitter audio input (microphone or phone patch input
see Chapter 4), there may be less problems with spuri-
ous signals (usua11y due to overdrivi.ng the transmitter
audio stages). Since the tone frequencies are high, the
harmonies and most distortion products occur at audio
frequencies beyond the audio passband of the transmitter
and should therefore not 5e tranpmitted.
Disadvantages:
1. The relatively high audio frequencies used in the high
tone set may not fa1I within the audio frequency res-
ponse of the receiver or transmitter. In general, the
standard amateur shift, 170 Hz, will pass most current
receivers and transmitters (tfre Collins S-Li.ne is an ex-
ception). However, few pieces of equipment will pass
the tones for both reeeiving and transmitting 425 or 850
shift with high tones (tfre Drake TR-7 is an exception).
The use of high tone demodulators for HF RTTY is there-
fore restricted to transmission of just 170 shift, and
only receivers lncorporating either a variable BFO or
pass-band tuning wi.11 receive all three shifts.
2. Hieh tones are not the IARU standard and will not be
compatible with VHF AFSK in many countries of the world.

PAGE 16
LOW TONES (Mark = 1275 Hz, Space = 1445, 1700, or 2125 Hz):
Advantages:
1. Low tones are the IARU international standard and their
use assures compatibillty with VHF AFSK operations in
many areas of the world.
2. Low tones can be used with virtually all SSB receivers
and transmitters for all three standard shifts.
Variable BFO or passband tuning features are not re-
quired to assure good recepti.on of 425 and 850 Hz shlft
stations.
Dl sadvantages:
'l . Low tones are not compatible with existing U.S. VHF
AFSK operations. Since there ls a great deal of high
tone AFSK equipment already in use in the United States
and neighboring countries, it is unreasonable to expeet
that the U.S. standard will shift to low tones.
2. When 1ow tones are used with a LSB transmitter to gener-
ate F1 RTTY emlssions (see Chapter 4), there is a strong
probabillty that over-drivlng the transmitter audio and
modulator stages will result in spurious harmonics and
mixer products that will be radiated. 0f coursef these
problems will not occur if the audio drive IeveI is
properly set.
Although you may develop your own personal preferences, w€ recommend
that you consider the following operating conditions as a starting
point:
In the United States:
Use HIGH tones for all VHF AFSK amateur communicatlons
normal 170 Hz shift HF operation; use LOW tones when
HF commercial RTTY statlons unless you have a receiver
variable pitch BFO or with IF pqss-band tuning. The
applies to use of the older Collins S-Linc equipment
tones for all HF operations, amateur or commercial.
In Europe (and all other areas where IARU standards apply):
and for
recei ving
with a
excepti on
use LOW
Use LOW tones exclusively for both VHF AFSK and HF operations.
The only exception would be when you communicate with another VHF
AFSK station who is using HIGH tones.