Hal Communications ST-7000 User manual

ST-7000
HF Demodulator for Packet Radio
Copyright © 1988 by HAL Communications Corp., Urbana, Illinois. Printed in
the United States of America. All rights reserved. Contents of this
publication may not be reproduced in any form without written permission of the
copyright owner.
870-07000
August, 1988 Printing

ST-7000 HF DEMODULATOR FOR PACKET RADIO
CONTENTS:
CHAPTER 1. UNPACKING AND INSPECTION................................... 1
CHAPTER 2. INSTALLATION ............................................... 2
2.1 DC Power............................................. 4
2.2
HF Radio Connection .................................. 4
2.2.1 HF Receive Audio .............................. 6
2.2.2
HF Transmit Audio ............................. 6
2.2.3
HF PTT Connection ............................. 7
2.2.4
HF GROUND Connection.......................... 7
2.3
Packet Controller Connections ........................ 8
2.3.1 TNC AUDIO Interface ........................... 8
2.3.2
TNC TTL I/0 Connections ....................... 9
2.3.3 RPC-2000 RS232
I/0 Connections ................ 12
2.4 VHF RADIO Connection................................. 14
CHAPTER 3. OPERATION .................................................. 15
3.1 Controls and Indicators .............................. 15
3.1.1 HF/VHF Switch................................. 15
3.1.2 SHIFT Switch.................................. 15
3.1.3 THRESHOLD Control............................. 16
3.1.4 Tuning Indicator .............................. 16
3.2 Use of the ST-7000 ................................... 18
3.2.1 General Considerations ........................ 18
3.2.2 HF Packet Operation ........................... 18
3.2.3 HF R TTY and AMTOR Operation ................... 19
3.2.3.1 HF PTT Control....................... 19
3.2.3.2 HF RX Data Squelch ................... 20
3.2.3.3
HF Transmit Tone ON/OFF .............. 20
CHAPTER 4. THEORY OF OPERATION........................................ 22
4.1 AF Input Filters ...................................... 23
4.2 Receive Audio AGC ..................................... 23
4.3 Mark Filter -600 Hz Shift ............................ 23
4.4 Space
Filter -600 Hz Shift ........................... 24
4.5 200 Hz
Detector and SHIFT Switch ...................... 24
4.6
HF Transmit Tone Generator............................ 25
4.7 RS232 and TTL I/0 Interface ........................... 26
4.8
TNC Audio Modem....................................... 26
4.9
TNC Audio Interface and PTT ........................... 27
4.10 Power Supplies ........................................ 27
4.11 Tuning Indicator ...................................... 28
4.12 Threshold Circuit ..................................... 28
4.13 ST-7000 Circuit Board Arrangement..................... 28
CHAPTER 5. TEST AND ALIGNMENT ......................................... 43
CHAPTER 6. SPECIFICATIONS ............................................. 49
LIMITED WARRANTY
........................................... 50

ILLUSTRATIONS:
FIGURE 2.I ST-7000 REAR PANEL.................................... 2
FIGURE 2.2 ST-7000 INTERNAL JUMPER LOCATIONS..................... 3
FIGURE 2.3 HF RADIO CONNECTIONS .................................. 5
FIGURE 2.4 AUDIO TNC INTERFACE CONNECTIONS....................... IO
FIGURE 2.5 TTL TNC INTERFACE CONNECTIONS......................... II
FIGURE 2.6 RS-232 TNC INTERFACE CONNECTIONS ...................... I3
FIGURE 3.I ST-7000 FRONT PANEL................................... I5
FIGURE 3.2 TUNING INDICATOR EXAMPLES............................. I7
FIGURE 4.I ST-7000 BLOCK DIAGRAM................................. 2I
FIGURE 4.2 AUDIO INPUT FILTERS................................... 29
FIGURE 4.3 RECEIVE AGC CIRCUIT................................... 30
FIGURE 4.4 600 HZ MARK FILTER .................................... 3I
FIGURE 4.5 600 HZ SPACE FILTER ................................... 32
FIGURE 4.6 200 HZ DETECTOR ....................................... 33
FIGURE 4.7 HF AFSK GENERATOR..................................... 34
FIGURE 4.8 RS-232 AND TTL 1/0 INTERFACE .......................... 35
FIGURE 4.9 TNC AUDIO MODEM....................................... 36
FIGURE 4.IOTNC AUDIO I/0 AND HF PTT .............................. 37
FIGURE 4.II ST-7000 POWER SUPPLIES ................................ 38
FIGURE 4.I2TUNING INDICATOR...................................... 39
FIGURE 4.I3THRESHOLD AND CARRIER DETECT.......................... 40
FIGURE 4.I4ST-7000 MAIN CIRCUIT BOARD............................ 4I
FIGURE 4.I5ST-7000 DISPLAY CIRCUIT BOARD......................... 42

HAL COMMUNICATIONS CORP.
ST-7000
HF Demodulator for Packet Radio
Operator's Manual
CHAPTER 1
UNPACKING AND INSPECTION
When
unpacking the ST-7000, carefully inspect the shipping carton and the
cabinet for shipping damage. Any evidence of shipping damage should be
immediately reported to your shipping carrier. Be sure to save all packing
materials if damage is found - the shipping carrier will want to inspect them.
Before discarding the packing materials check that you have all parts and
accessories listed below. If any are found missing, notify HAL Communications
Corp. immediately.
Be sure to fill-out and mail the enclosed Warranty Card to HAL Communications.
1 900-07000 ST-7000
HF Demodulator
The following accessories are included with the ST-7000:
1 770-05000
1 800-01002
1 960-07232
3 355-00054
1 870-07000
Spare 0.5A
fuse
115VAC to 12VDC Power Supply
5-pin
TTL I/0 Cable
5-pin
DIN to Phono Cable
ST-7000
Preliminary Operator's Manual
The following accessories are available at extra cost:
855-00006 RS232C Cable
333-20250 DB25
Connector
333-51228 DB25 Connector Shell
310-00064 5-pin DIN
Connector
327-05000 5-pin TTL Connector
You may also be interested in the following related HAL products:
RPC-2000
Radio Packet Controller Board (for PC-XT & DS-3200)
DS-3200
Radio Data Terminal (100% PC-XT Compatible)
HAL880815

ST-7000 OPERATOR'S MANUAL
PAGE 2
CHAPTER 2
INSTALLATION
The ST-7000 is a modem (MOdulator/DEModulator) device that connects between
your packet controller (also called "TNC") and an HF receiver-transmitter. The
packet controller is NOT included in the ST-7000. Proper installation of the
ST-7000 requires (a) DC power connection, (b) HF radio connection, and (c)
packet controller connection.
The rear panel of the ST-7000 is shown below in Figure 2.1. All connections to
the ST-7000 are made to one or more of these connectors.
FIGURE 2.1 ST-7000 REAR PANEL
Many of the 1/0 connections available on the ST-7000 will require changing of
internal jumpers. Therefore, when making the first installation, REMOVE the
ST-7000 top cover before starting. There are NO hazardous voltages inside the
ST-7000, but use care to avoid damaging components or accidently shorting out
circuits with stray wires while power is applied to the ST-7000. To remove the
top cover:
1. Remove all cables connected to the ST-7000 rear panel.
2. Remove the two screws at each side of the cabinet (4 screws total).
3. Lift from the front and swivel the top so that it lies upside down
behind the ST-7000.
4. Unplug the ground jumper wire and set the top cover aside.
5. Preliminary tests will be made with the cover OFF. The cabinet
cover may be re-assembled after all jumpers and connections are set.
Location of the internal jumpers is shown in Figure 2.2.
HAL880815

ST-7000 OPERATOR'S MANUAL
PAGE 3
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FIGURE 2.2 ST-7000 INTERNAL JUMPER LOCATIONS
HAL880815
F1
.SASB

ST-7000 OPERATOR'S MANUAL
PAGE 4
2.1 DC Power:
The ST-7000 requires a minimum of 13 VDC @ 225 rna power. This is supplied by
the enclosed accessory DC Power Supply or from other sources of DC power. The
connector on the HAL DC Power Supply is already set-up for the ST-7000. If
using your own DC power source, be sure to observe correct polarity. The ST-
7000
DC connector uses the center pin as the oositive terminal. BE CAREFUL!
Other devices with similar appearing DC connectors may use a different polarity
as well as a different diameter center pin. If you accidently reverse the
power supply polarity, it should not damage the ST-7000 circuits, but it will
blow
the fuse inside the ST-7000! Any DC power supply used with the ST-7000
should supply 13.5 to 15 VDC at 0.250 A.
2.2 HF Radio Connection:
The HF Radio equipment is connected to the "HF RADIO" 5-pin DIN connector on
the rear panel. If you are preparing your own cables, pay close attention to
the pin numbers marked on the rear panel. The "industry standard" pin
numbering on these connectors does NOT go in a logical progression!
Connections are as follows:
PIN USE
1
Transmit tones to HF transmitter audio input
2 GROUND
3 Push-to-Talk (PTT) to transmit/receive control
4 Audio output of HF receiver
5 Not used
Shell
GROUND (Cable shields)
An accessory cable (P /N 355-00054) is supplied that conveniently converts the
5-pin DIN connections to individual "RCA-style" phono plugs. Some HF radio
equipment (notably Ten-Tee) have rear panel phono connectors to which this
adapter cable may be directly connected. Other radio connectors may require
that you either make your own complete cable set OR adapt the phono connector
to one that matches the connector on your radio. For HF radio connections, the
following color code applies to the HAL adapter cable.
CABLE
COLOR
RED
BLACK
WHITE
YELLOW
HF RADIO CONNECTIONS
DIN to PHONO Adapter Cable
USE
TONES
TO HF TRANSMITTER
Push-To- Talk (PTT)
AUDIO FROM HF RECEIVER
-- not used --
ST-7000
HF RADIO
PIN NO.
1
3
4
5
NOTE: Ground (pin 2) is connected to ALL phono connectors
A typical ST-7000 to HF Transceiver connection is shown in Figure 2.3. A
detailed discussion of the requirements for each connection is given in the
sections following Figure 2.3.
HAL880815

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VI

ST-7000 OPERATOR'S MANUAL
PAGE 6
2.2.1 HF Receive .Audio:
The ST-7000 is designed to work equally well from either an 8 ohm or 600 ohm
audio output on your receiver. The simplest connection is direct to the
receiver speaker output terminals. Set the receiver volume control to a
comfortable speaker level and the ST-7000 AGC circuit will do the rest. If you
have a constant level 600 ohm audio output, by all means use it. Some radios
have a phone patch output on the rear panel - if so, use it. The ST-7000 may
also work with some "recorder" outputs provided on some receivers. However,
the output impedance and voltage level output may not provide sufficient audio
signal for the ST-7000 and may cause reduced performance during signal fades.
Be
sure to use shielded cables between the ST-7000 and the receiver audio
output connector.
2.2.2
HF Transmit Audio:
The ST-7000 is set at the factory for a level of -20 dBm (80 mY) to the
transmit audio output connector. This level may be reduced to as low as a few
millivolts (-50 dBm) by adjustment of the "HF AFSK" screw-driver control on the
rear panel. Conversely, if ypur transmitter system requires a higher level
output, internal jumper Jl2 may be installed to increase the maximum level
output to 0 dBm (800 mY). With J12 in place, the "HF AFSK" control will adjust
over the -30 to 0 dBm range (25 to 800 mY). The microphone input of most SSB
transmitters will require a level of between -40 and -20 dBm (8 to 80 mY). Be
sure to use a shielded cable between the ST-7000 and the transmitter audio
input.
Use the following procedure to set the "HF AFSK" level control.
1. Turn OFF transmitter VOX and SPEECH PROCESSOR features.
2. Set the transmitter to LSB mode.
3. Set transmit MIC LEVEL to "0".
4. Set ST-7000 to "200" SHIFT and turn ON ("HF" position).
5. Set ST-7000 HF AFSK to maximum (full CW as viewed from rear).
6. Be sure transmitter is connected to a load (antenna or dummy load).
7. Turn transmitter to XMIT.
8. Slowly increase MIC LEVEL until 50% of full transmitter power output is
noticed.
Note the position of the MIC LEVEL knob.
9. Turn transmitter OFF.
10. If 50% transmitter power is achieved in first third of the MIC LEVEL
rotation, change the setting of "HF AFSK" (CCW) and try step 8 again.
Keep adjusting MIC LEVEL and "HF AFSK" until 50% transmitter power is
achieved at between 1/3 and 1/2 rotation of the MIC LEVEL control.
HAL880815

ST-7000 OPERATOR'S MANUAL PAGE 7
11. If 50% transmitter power is achieved at greater than 1/2 rotation of
the MIC LEVEL control, install jumper Jl2 inside the ST-7000. Be sure
to turn OFF the ST-7000 before removing its cover. The jumper for J12
is
installed at the factory with just one pin covered. Unplug the jumper
and re-install it to short out the pins at Jl2. After installing the
Jl2 jumper, go back to step 8 and adjust MIC LEVEL.
12. If installing Jl2 still does not give adequate MIC LEVEL settings, turn
everything OFF and inspect your cables -something is WRONG!
13. Set the MIC LEVEL control to the desired transmitter output level. Since
most
transmitters are designed for SSB voice (50% duty cycle), using less
than full power for data is a prudent move and may greatly prolong the
life of your transmitter. The difference between 1/2 power and full power
is only 1/2 an S-unit on the other station's receiver, hardly worth the
risk to your transmitter!
2.2.3 HF PTT Connection:
The ST-7000 Push-to- Talk (PTT) output is a relay contact switched to ground.
The relay can adequately switch PTT control lines that have up to 50 VDC at a
maximum current of 0.25 amperes. This should switch virtually ANY transmitter
or transceiver available. A shielded cable is recommended but not required for
the PTT connection. Often, a two-conductor shielded cable can be used to carry
both transmit audio and PTT signals from the ST-7000 to the transmitter
microphone input jack.
The ST-7000 HF PTT output includes a 20 second safety timer for packet radio.
This timer prevents long key-down periods, even if your TNC or computer
malfunctions. This safety feature helps prevent transmitter burn-out in a
malfunctioning packet radio system. The timer resets after each packet is sent
and the TNC PTT control line returns to receive state.
However, the ST-7000 may also be used as an RTTY or AMTOR FEC modem. In this
case, long key-down transmitter periods are common and internal jumper J7 may
be installed to defeat the PTT safety timer. To defeat the timer, move the
jumper plug so that it shorts the two pins ·at 17. The jumper plug is
positioned at the factory to cover one but not both pins of J7 (PTT safety
timer ON).
2.2.4
HF GROUND Connection:
The ST-7000 MUST be adequately grounded to the HF transmitter and receiver.
Grounding is done in TWO steps - (I) an audio ground obtained through the
shielded cables between the HF RADIO connector and the transmitter/receiver
audio connections, and (2) an RF ground between cabinets. The importance of a
good
RF .ground cannot be over-emphasized! Use a short length of 1/4" shield
braid directly between the transmitter /receiver cabinet and the ST-7000 rear
panel ground screw. An earth ground for the entire radio station is a good
safety feature but does NOT replace the need for a seoarate RF ground
connection.
HAL880815