Hallicrafters HA-1, Operating And Service Instructions

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SECTION I
GENERAL
1-1. DESCRIPTION
The Hallicrafters Model HA-1 T.O.Keyer ® employs digital circuitry, similar
to that found in modern digital computers, to form perfect code characters at any
speed. Experienced operators appreciate its stability and precision of operation,
and novice operators discover a new command of CW that leads to proficiency
and unsuspected enjoyment. The keyer operates much in the same way as a tape
transmitter; the dash-dot and mark-space ratios remain constant over the speed
range and the speed and mark-space adjustments are completely independent.
The key lever is a remote control unit that may be placed in any convenient
operating position. This conserves the operating area, permits ready mechanical
adjustments, and allows the operator his choice of key levers.
Additional features of the keyer include a pleasant sidetone signal with
volume control for practice, instruction or monitoring ... an exceptionally wide
speed range ... a silent mercury-wetted relay of virtually unlimited life ... complete
immunity to line-voltage fluctuations and RF pickup ... rear connections for
break-in operation and auxiliary control, and for external sidetone and key lever
connections ... and a transformer power supply, with silicon rectifiers and
complete voltage regulation for top reliability.
1-2. STANDARDS FOR THE INTERNATIONAL MORSE CODE
The International Morse code replaced the older Morse code for radio
communications when the tape perforator and keying head, along with the high-
speed ink-slip recorder, were developed for commercial service. This early
automation of our CW is still widely employed, handling traffic comfortably at 300
WPM. The perforator and keying head provide the "perfect fist" and the standards
for CW which make it easy to send and receive with the proper scientific
economy.
The relative duration of the dot and the space is called the mark-space ratio,
usually adjusted for 1-to-1. A dash is formed by bridging the space between two
dots. The spaces between dots and dashes in a letter are uniform. A standard
word is equivalent to 24 dot and spaces. 10 WPM (words per minute) is therefore
240 dots per minute, or 4 dots per second.