Hallicrafters HA-1, Operating And Service Instructions

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The effect of the adjustment on keying characteristics is especially evident
when listening to the keyed monitor signal with the unit running at its highest
speed.
To set the WEIGHT adjustment for a 1 to 1 ratio at the relay terminals, pro-
ceed as follows:
(1) Disconnect the keying leads from the transmitter and reconnect the
leads to an ohmmeter. Set the ohmmeter to its lowest range.
(2) key a continuous series of dots at a fairly high speed (approximately
45 WPM).
(3) Adjust the WEIGHT control for a half-scale ohmmeter deflection.
Connecting an oscilloscope to the output of the transmitter so that the keyed
output may be seen is a more accurate means of setting the desired ratio. This
permits adjustment of the overall keying characteristic of the station although the
method mentioned earlier, will generally suffice for most systems.
SECTION V
OPERATION
5-1. GENERAL
Rapid effortless operation of the keyer requires a certain "knack" that comes
only with practice. Habits acquired by the use of conventional keys will have to be
overcome before the full capabilities of the keyer can be realized.
Care should be exercised in the selection of a key lever for use with the
Model HA-1 keying unit; one incorporating good mechanical construction,
particularly at the pivot and contact points, is a desirable and will provide long
reliable service.
Manufacturer's recommendations as to the keyer lever's adjustment should
be closely followed for optimum performance. It is desirable to adjust the dot-
dash contacts for the shortest possible excursion that will result in reliable make-
break action. Key lever contacts should be periodically inspected to prevent the
build-up of dirt and oxidation which can cause erratic keying.
5-2. OPERATING CHARACTERISTICS
The neon indicator on the front panel serves two functions: (1) it indicates
that the power is on and the unit ready for use, and (2) it serves as a visual
keying monitor. It will be noted that the indicator flashes once for each dot