Heathkit HKA 232 3 User Manual

Page 21

Status Indicator LEDB

Note that all markings below the LEDs refer to packet
operation, while markings above the LEDs refer to all other

modes.

The following table describes these indicators from

left to right and from top to bottom.

Status Operating

LED Mode Description

MULT Packet Lights when multiple packet connections exist.

SEND Packet Lights when the HK-ZJZ is transmitting a packet.
(PTT is active.)

ERROR ARQ Lights when the AMTOR (AMateur Teleprinting Over
Radio) system receives errors from another system.

CONV Packet Lights when the system is in the conversation mode.

IDLE ARQ/FEC Lights when the AHTOR system sends synchronizing or
idle characters.

PHASE ARQ Lights when the AMTOR system sends its SELCAL
(Selective Call) or phasing signals to another
station.

STBY ARQ Lights when the AMTOR system is available to answer
an ARQ SELCAL from another station.

STA Packet The STAtus LED lights when the unit sends a packet
but doesnt get an acknowledgement.

CON Packet Lights when the HK-23Z is connected to another packet
radio station.

RQ ARQ Lights when another AMTOR station requests a repeat
of previous information blocks.

C511) Packet Lights when the system is in the Command mode.

TFC ARQ/FEC Lights when the AMTDR system sends information.

TRANS Packet Lights when the the system is in the transparent
mode.

OVER ARQ Lights when the AMTDR system sends a change~over
command to another station.

3-5

Page 24

3-8

Pin-out Tables

POWER
Connector Description
Center +13 VDC, 700 mA from external
power supply.
Sleeve Ground return.

RX-IN AUDIO 1 and 2

Connector Description

Tip Receiver audio signal. May be
used as output or an input.

Sleeve Ground return.

RADIO 1 and 2

Pin

Description

RX AUDIO: From the receivers audio output.
Couples the AFSK signal to the internal
demodulator. Signal level can be from less than
10 mV peak-to-peak to several volts. An internal
limiter prevents overloading the input. This line
connects directly to the associated RX-IN AUDIO
line.

TX AUDIO: AFSK output from the HK-232 to the
microphone input of the transmitter. Signal level
adjusted by the AFSK LEVEL control. This can vary
from one transmitter to another, but is typically
10 to 20 mV peak-to-peak.

Page 32

3-16

PRINTER INTERFACE

Here is the printer interface wiring for EPSON-type dot
matrix graphics printers. The table also shows a partial
schematic of the RS-232 leads for reference. See Computer
Interface" for detailed wiring information. For other
printer manufacturers, refer to their technical literature.
This cable is available wired as #230-8157.

Ell-232 25-Pin Computer

DCE Connector Connector

1 I

2 (

3 >

A» <

5 > As required by the computer.

6 >

7 -l-

8 >

20 < Printer

Pin No.

_ Chassis Ground - 17

22 >- > Strobe > > 1

13 > > 131 > > 2

14 > > D2 > ) 3

15 > > D3 > > A

16 > > D4 > > 5

l7 > > DS ) > 6

18 ) > D6 > > 7

19 > > D7 > > 8

21 > > D8 > > 9

23 <- < ACK < 200/]. WW 10

24 <- < BUSY

-\

Use as many conductors
as are available to keep - 19 through 29
the data ground impedance
low.

Page 56

3-40

COMMAND i KNEHONIC DEFAULT FUNCTION
I'BAUD T13 1200 baud Set terminal data rate.
TCLEAR TC [mediate

command Non-packet clear Transmit Buffer.
TLME TI $14 insert "send time" in text.
TRACE TRAC OFF Hex dump of packet frame.
TRANS T Immediate

command Start Transparent Data Mode.
lRFLOW TRF OFF Terminal flow std-Transparent.
TRIES THE 0 (zero) Show or force retry count.
TXDELAY TXD 30 (300 mS) PTT key-to-data delay (x10 mS).
TXFLOL-fi TXF OFF HK-232 flow control-Transparent.
TXREV TXR OFF Reverse transmitted data sense.
UNPROTO U CQ Path/address to send U1 frames.
USERS US 1 Number of multi~connections that

are allowed.

USOS USO OFF RTTY "unshift on space."
VHF V ON Packet-wide or narrow shift.
WIDESHFT WI OFF RTTY-wide or narrow shift.
WORDOUT WO OFF RTTY-word or character output.
WRU WR OFF Turn on auto-answerback (AAB).
XFLOW XF ON Software flow control.
XMIT X Immediate

command Start transmission-key PTT.
XMTTOK XMITO ON PTT line can be keyed. I
XOFF X0 $13 Stop sending data to terminal.
XON XON $11 Resume sending data to terminal.

Page 78

The active low-pass filter removes any residual pulses
caused by the modulating tones. The VHF control line
selects the appropriate cutoff frequency: about 1500 Hz for
the packet, RTTY wide, and facsimile modes; and 400 Hz for
the Morse, RTTY narrow, and AMTOR modes. The filter output
connects to a TTL converter, which squares up the signal and
inverts it so that a logic one corresponds to a mark. It
then couples the signal on the RD signal line to the
HDLC/serial port (High-level Data Link ControllerL

Transmitter Circuits Block Diagram

The tranmitter circuits consist of the column of blocks on
the right side of the diagram, starting with the squelch
block and ending with the keyer.

The squelch circuit couples the external receiver squelch
status through PA7 to the parallel port. The HK-232
monitors the squelch to prevent transmitting if the channel
is already active. Simply checking the status of the
threshold circuits and mark/space detectors isn't enough.
These circuits will inform the CPU that FSK information is
present, but not if some other form of communication, such
as voice, is taking place. Note that the HK-232 only uses
the squelch circuit in the packet mode. In other modes, the
operator must decide when to transmit

The push-to-talk circuits connect to the microphone PTT line
on the external transmitter. The HK-232 controls this line
though the PTTN line from the serial port. Jumper plugs in
the TNC allow selecting an active high or low to key the
transmitter. As discussed in the previous two paragraphm
the HK-232 won't key PTT if the channel is active in the
packet mode.

The watchdog timer circuit disables the PTT circuits ifa
failure occurs in the HK-232. The HK-232 pulses the serial
port PTTW line roughly once every 5 m8 to keep the timer
inactive. The exact period will jitter by about 2 mS
because the CPU must constantly process interrupt requests
from the parallel port timer. (See Digital Circuits Block
Diagram for more informationJ If a failure occurred and
PTTW stopped pulsing, the watchdog timer would time out
after about 60 mS and shut down the push-to-talk switch.

5-5

Page 98

If a major component fails, such as the CPU or HDLC, it%
likely that PTTW would stop pulsing. If so, Q10 would turn
off and C55 would start charging through R146. After about
60 ms, the 5.1 V zener diode at 027 would conduct and turn

on Q3. In turn, Q3 would turn off Q4 and Q5 to shut down
the transmitter.

AFSX HODULATOR

The Audio-Frequency-Shift-Keying (AFSK) modulator is an
XR2206 function generator at U40. Electronic switches at
U35A, U35C, and U35D select the operating frequency while
various inverters in U37, U38, and U39 interface U40 to the
parallel and HDLC ports (U6 and U7 on the Digital Circuits
schematic).

Depending on the operating mode, the modulating signal can
arrive through one of two paths. In the packet radio mode,
the TD line (from U7-15) sends the serial data through U395
to the open-collector inverter at U38B. At this time, PA6
(from U6-27) is high to prevent blocking the signal. In
other operating modes, TD goes high and PA6 generates the
serial data.

The outputs of the inverters couple through JPS to the
modulating input at U40-9. Internally, the signal connects
to a current switch labeled lSW. This section controls the
frequency of the VCO by selecting the resistor networks at
pins 8 and 9. Pin 8 generates the space tones when pin 9 is
low. In the wideshift mode, U35A closes and R165 sets the
frequency to 2220 Hz. For narrow modes, U35A opens and U350
closes to shift the space frequency to 2310 Hz. In the
Morse code mode, both switches are open so that no tone is
generated. when pin 9 is high, pin 7 sets the mark
frequency; this is 1200 Hz for wideshift/CW and 2llO Hz for
narrow shift. Optionally, R168 and R167 can be adjusted to
a 2100/l300-Hz shift for facsimile transmission. Adjusting
any of these controls CCW will lower the frequency, while cw
raises in

5-25

Page 117

5-44

Parallel Port Interrupt Operation

The following table shows the interrupts available in order
from highest priority to lowest.

l. Timer 3

2. Radio Interface (PAO-PA7)

3. Timer 2

4. Printer Data & Mode/Status LEDs (PBO-PB7)
5. Timer 1

During powerup, the HK-232 programs only timer l to generate
interrupts. This occurs at 1 ms intervals and is based on
the 4.0 MHz clock entering U6-16. To begin the interrupt,
U6 places a logic zero on the interrupt request line, pin
24. When the 280 is ready to process the interrupt, it
asserts the interrupt-acknowledge line at 116-25. U6 will
then place the interrupt vector on D0-D7, which the 280 uses
to determine the location of the interrupt program.

U6-l7 is a hardware interrupt-enable input. If this line is
low, the IC can't generate an interrupt request. Rll
permanently ties this line high. U6-l8 is the interrupt-
enable output and connects to U7-7, the serial port
interrupt enable input. If U6 is performing an interrupt
request and acknowledge cycle, pin 18 goes low and disables
the interrupt circuits in U7. This gives the timer highest
priority, which is necessary for the 280 to maintain its
various timekeeping functions--such as time-of-day and
determining Morse code speed.

Page 118

Radio Interface (PAO-PA7)

Parallel port A controls and monitors most of the functions
that interface the HK-232 to a radio. These are shown in
the following table.

Active
Bit Pin Function Level Direction
PA7 26 Squelch In
PAS 27 RTTY transmit data Out
PAS 28 Wide shift enable (VHF) High Out
FAA 29 Tone enable High Out
PA3 30 Calibration In
PA2 31 st enable (CW/NCW) High Out
PAL 32 CW keyer Low Out
FAQ 33 Narrow shift enable (HF) Low Out

PA7 may be programmed with the SQ ON/OFF command to be
either active-high or active-low . PA6 doesn't have a
defined active state, but rather pulses when the HK-232
transmits data in any of the non-packet modes. PA3 counts
the transitions on the digital output of U40, the XR2206
tone generaton

PA2 switches the HK-232 between the CW and FSK modes. When
high, it enables FSK for Packet and RTTY; when low, PA2
enables CW. PA5, PA2 and PAO work together to determine the
amount of frequency shift

PA5 PA2 PAO Function

Narrow shift FSK
wide shift FSK
CW

Or-O

l
l
0

D-D-O

0n the Analog Circuits schematic, U390 and U37D double-
invert PAS to generate the VHF control line. The open-
collector inverter at U37D and the pullup resistor at R182
convert the signal from TTL to the +13 V signal required by
the 4066B FET switches. U37A inverts PA2 to form the CW
line, while U39A and U37F form the NOW line. U37C converts
PAC to the HF control line.

5-45

Page 155

TROUBZZS/IOO 7/6

EQUIPMENT NEEDED 9-3
SERVICE HINTS 9-4
Digital Circuits 9-4
Unit Dead or Locked Up 9-4
RS-23ZC Port Defective 9-8
Parallel Port Defective 9-9
Analog Circuits 9-10
Modem Cannot Be Calibrated 9-10
Transmitter Cannot Be Keyed 9*11
Transmitted Signals Not Copyable By Other Stations 9-11
Transmits Packets Okay, But Nothing Else 9-12
Will Not Transmit Packets, Other Modes Okay 9'12
Received Signals Not Copyable 9-12
Receives Packets Okay, But Nothing Else 9-12
Cannot Detect Packets, Other Modes Okay 9-12
Receiver Filter Checks 9-13
WAVEFORMS 9-22
Overview 9-22
Analog Circuits Waveforms 9-22
Clock and Power Supply Waveforms 9-27
HDLC Waveforms 9-29
Logic Circuits Waveforms 9*30
RS-232C Waveforms 9-34
Watchdog Timer Waveforms 9-35
FINAL CHECKS 9-36

Page 157

EQUIPMENT NEEDED

To troubleshoot the HK-232, you will need the following test
equipment. The test equipment specifications should meet or
exceed those listed after each item. The suggested model
numbers at the end of each item will fulfill these
requirements.

Oscilloscope: DC to 25 MHz, dual trace, triggered sweep,
10-4225 or equivalent.

Low-Capacitance Oscilloscope Probe: Input capacitance
adjustable between 15-50 pF, A-nS rise time. Heath PKw-lOS
or equivalent.

Logic Probe: DC to 20 MHz, capable of detecting 10 118
single pulses. Indicates logic one, logic zero, and high-
impedance states. Heath IT-7410, or Hewlett-Packard
PIP-545A, or equivalent.

Digital Multimeter: High-impedance input. Measures ohms,
AC/DC voltage, and AC/DC current. Heath SM~77 or
equivalent.

Frequency Counter: Able to measure from 5 Hz to 5l2 MHZ
with a resolution from 0.1 Hz to 1000 Hz. Heath 114-2420 or
equivalent.

Audio Signal Generator: Able to generate sine waves from
1 Hz to 100 kHz. Amplitude adjustable from 1 mV to 10 V
RMS. Heath 16-18 or equivalent.

DCPower Supply: 12 VDC, 1 A. Heath #150-333 or
equivalent.

Computer Terminal: RS-232C and ASCII compatible. Data rate
adjustable to 1200 baud. Heath H-l9 or equivalent.
Alternately, you can use a computer and terminal emulation
software, Such as the Heath HS*158 and HUGMCP (885-3033-37
from Heath Users' Group).

9-3