‰  NOW 40 WPM  ‰  
THIS ARTICLE.  PAUL NEWLAND, AD7I, WAS FIRST LICENSED AS A NOVICE IN 1971
AT AGE 15.  HE SOON BECAME FASCINATED WITH RTTY WHEN HE SAW AN 80 METER
RTTY AUTOSTART SYSTEM IN OPERATION.  IN THE MID 1980S, PAUL DEVELOPED HIS
OWN MICROCOMPUTER BASED AMTOR SYSTEM AND WAS PART OF THE TEAM THAT
DEVELOPED THE TAPR TNC 2 PACKET RADIO CONTROLLER.  PAUL IS AN ARRL LIFE
MEMBER.  HE EARNED A BSEL FROM CAL POLY, SAN LUIS OBISPO, AND A MSE ECE
FROM THE UNIVERSITY OF MICHIGAN ANN ARBO

IN THE CASE OF FSK TRANSMISSIONS, IT WILL BE NECESSARY TO GIVE THE PTT
DRIVER SOME HANG TIME.  THATS THE FUNCTION OF THE RE TRIGGERABLE TIMER U3B
AND ASSOCIATED COMPONENTS.  SW4 ALLOWS THE USER TO SELECT WHETHER THE PTT
FOLLOWS THE CONTROL TONE WITH OR WITHOUT PTT HANG TIME.  WHEN OPERATING IN
AFSK MODE, SWITCH SW4 IS SET TO THE OUTPUT OF Q1 U3A, WHICH WILL CAUSE THE
TRANSMITTER PTT TO VERY CLOSELY 4 MS FOLLOW THE TRANSMITTER CONTROL TONE.
THE CW RELAY IS ALWAYS DRIVEN BY Q1 WITH NO TX HANG TIME.  FOR FSK
OPERATION, THE CONTROL TONE NOT ONLY REPRESENTS THE MARK ONE FOR THE FSK
CONTROL INPUT TO THE TRANSMITTER, THAT SAME TONE WILL BE USED TO CONTROL
THE TRANSMITTER PTT.  IN THIS CASE, WE NEED SOME TRANSMITTER HANG TIME TO
BRIDGE THE TIMES WHEN FSK SPACE IS BEING TRANSMITTED.  SO FOR FSK
TRANSMISSION, SW4 IS SET TO THE OUTPUT OF Q3.  YOU DONT NECESSARILY NEED TO
USE RELAYS BECAUSE YOU COULD USE ONE OR TWO TRANSISTORS TO PROVIDE AN OPEN
COLLECTOR OR OPEN DRAIN OUTPUT TO CONTROL THE TRANSMITTER PTT AND CW
CIRCUITS.  I USED A PAN CHANG SIP 1A05 REED RELAY.  IT TAKES NO MORE THAN
300 US TO ACTIVATE OR RELEASE, EVEN WITH THE INCLUDED VOLTAGE SNUBBER DIODE
ACROSS THE COIL.  THE CONTACT BOUNCE TIME DURING ACTIVATION IS INCLUDED IN
THAT 300 US.  CAUTION SNUBBER CIRCUITS, LIKE THE REVERSE BIASED DIODE ON
RELAY COILS, CAN SIGNIFICANTLY DELAY THE RELEASE TIME OF A RELAY WHEN THE

DRIVER CONNECTED TO THE RELAY INTERRUPTS THE RELAY COIL CURRENT.  THIS IS
ESPECIALLY TRUE WHEN THE RELAY COIL HAS A LARGE INDUCTANCE.  I CHOSE TO USE
A DB 9 CONNECTOR FOR THE RADIO I/O INTERFACE AND A 3R5 MILLIMETER TRS JACK
FOR THE EXTERNAL SPEAKER.  SETUP FIRST, CONNECT THE INTERFACE TO YOUR
COMPUTER AND ENSURE THAT YOUR COMPUTER RECOGNIZES THE USB SOUND DONGLE.
THEN, ENSURE THAT THE AUDIO LEVEL SETTINGS WITHIN YOUR COMPUTER FOR THE
DONGLE, BOTH MICROPHONE AND SPEAKER OUTPUT, ARE AT OR NEAR MAXIMUM.  HOW
YOU SET UP THE LEVELS DEPENDS ON YOUR COMPUTER, BUT SOME QUICK INTERNET
SEARCHING SHOULD PROVIDE GUIDANCE.  ON YOUR RADIO, ENSURE THAT YOUR
TRANSMIT DRIVE CONTROL IS SET TO MINIMUM, SO IF YOUR TRANSMITTER IS ACTIVE
IT WILL PUT OUT MINIMUM POWER.  NEXT, CONNECT A CABLE FROM THE OUTPUT OF J2
PIN 1 TO THE MICROPHONE INPUT OF YOUR TRANSMITTER.  THEN CONNECT A CABLE
FROM THE OUTPUT OF J2 PIN 3 TO THE PTT INPUT OF YOUR TRANSMITTER.  DONT
FORGET THE GROUNDS ON J2 PIN 6.  ON THE INTERFACE, ADJUST SW3 TO SELECT
RIGHT CHANNEL AND SW4 TO SELECT FAST PTT OPERATION.  START YOUR FAVORITE
SOUND CARD DATA COMMUNICATION PROGRAM AND SELECT ANY MODE THAT SHOWS A
‰  END OF 40 WPM TEXT  ‰  QST DE W1AW  ƒ