W6IWI RTTY Notes

The Teletype model 15 and Flesher TU-170 Terminal Unit are on the air! A model 14 typing reperf and transmitter distributor will soon be online. When not being used for something else, the station is on the Green Keys autostart frequencies listed below. Frequency Type Day (MHz) Night (MHz) Notes Mark 14.083,875 7.083,875 Space 14.083,705 7.083,705 Space is 170 Hz below Mark US LSB 14.086,000 7.086,000 Mark tone 2.125 kHz, Space 2.295 kHz Center 14.083,790 7.083,790 Shift up 85 Hz for Mark, down 85 Hz for Space Navy MMM LSB 14.085,490 7.085,490 Mark tone 1.615 kHz, Space 1.785 kHz Navy LF LSB 14.084,790 7.084,790 Mark tone 915 Hz, Space 1085 Hz Europe LSB 14.085,830 7.085,830 Mark tone 1.955 kHz, Space 2.125 kHz

Resources

• Green Keys mailing list. A bunch of Teletype enthusiasts!
• Internet Teletype - Three AFSK streams to feed your Teletype!
• RTTY Sub-Bands - Suggested operating freqncies.
• Teletype Exchange - List of available equipment, equipment wanted, where to find, how to transport, and other info from the Green Keys mailing list.
• RTTY Electronics, P.O. Box 20101, El Sobrante CA 94820. Phone +1 510 222 3102. Email mr_rtty@pacbell.net. EXCELLENT source for Teletype parts.
  • Loop Supplies

    • 152950 150ma $20.00 - This is the supply I was using on a local loop. I am now using the supply within the TU-170 (below). It is a small open metal chassis with a transformer, a couple silicon diodes, and a capacitor. It has a D-hole that accepts an HKP fuse holder. I added a fuse holder, a line cord, and a terminal block for the DC output. When driving the loop, the voltage is 125 VDC. A 2.2k 10W resistor sets the loop current to about 60 mA. The voltage across the resistor is 122.7 VDC for a loop current of 55.8 mA.

    • 162361 500ma $30.00
    • REC29 200ma $35.00
• Teletype model 14 Transmitter Distributor
  • Army Technical Manual TM 11-2222, May 1951.
• Teletype model 15
  • Description
  • Adjustments
  • Parts
  • Model 15 Slow Motion Video
  • Sychronous Motor Measurements - The mechanical load on the motor varies with machine adjustment (such as clutch tension) and lubrication. There is more load on the motor when the machine is idling since the clutches are slipping. Here are the measurements on my model 15. The "running" column is with the space bar held down so the keyboard and printer clutches are released.

    Measurement	Idle	Running
    Current	2.5 A	2.48 A
    Power	79 W	70.5 W
    Apparent Power	297 VA	293 VA
    Power Factor	26 %	24 %

• Paper
  • White roll , 235 feet. $11.75 each for 3+
  • Iconex 90742200 - Roll of 8.44 inch wide by 235 feet long. $11.15 per roll with free shipping.
  • PM Company® Teleprinter Paper Roll, 8 7/16" x 235 ft, White - $9.64/roll
  • POS Supply - 8 7/16 inch by 225 feet, 12 rolls for $78.95 with free shipping
  • 2,700 Sheets 8.5 x 11 One Part - One Ply White 20 #, Heavy Weight, NO SIDE PERFORATIONS, Continuous Stock Computer Paper - $44.97
• Paper Tape - 11/16 inch paper tape for model 14/19 reperforator
  • Teletype Tape Distributor 11/16” Oiled Paper Tape, YELLOW, 2.0” Core (1) Case, $39.95 per case plus shipping
• Ribbons - Same ribbon used on model 14 typing reperf and model 15 page printer.
  • Swartz Ink SI-83-BKTE, also on Amazon, package of two (each includes two reels and reversing rivet), $7.00 + $4.99 shipping
  • Ribbons Unlimited 33P, $11.95 plus $4.99 flat rate shipping
• Printing Telegraph History
  • PRINTING TELEGRAPHY ... A NEW ERA BEGINS, Edward E. Kleinschmidt
  • Hell Feldfernschreiber teleprinter - A very clever dot matrix teleprinter. The transmit side transmitted vertically scanned pixels. The receive side uses a two turn helix to provide vertical scan and moves the paper tape to provide horizontal scan. The helix is inked by a saturated felt. A solenoid operated knife edge under the paper presses the paper to the inked helix when a pixel is to be printed. The two turn helix is very clever. Because of it, no synchronization is required between the transmitter and receiver. If the transmitter and receiver are perfectly "synchronized," the text appears on the tape as two rows of characters. If they are not synchronized, one complete line of text is on the tape with the other line split above and below the good line (it wraps from the top edge to the bottom edge). But, there is always a good line of text. If the speeds of the transmitter and receiver are slightly different, the text drifts towards the top or bottom of the tape, but a complete line is always printed.
• Terminal Units
  • Flesher TU-170 Terminal Unit - My notes on the TU-170
• Software
  • Droid RTTY - Great Android application that transmits and receives AFSK RTTY.
  • RTTY Demodulator for Linux - Mark and space bandpass filters drive subtractor which drives a zero cross detector. Latest version also decodes packet and CW.
  • Linux command line to copy ITTY
    curl -N -s http://internet-tty.net:8000/ITTY | lame --decode --quiet --mp3input - - | minimodem rtty -i -a -q --rx-one -R 11025 -f -
  • MMTTY - Teletype terminal and modem in software. Runs under Windows and drives transceiver through sound card. Also on the site is MMSTV for slow scan television