Heathkit HP 1144A Manual

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Page 13

SPECIFICATIONS

Output Voltage .............................

Maximum Output Current ..................
Power Requirements ........................
Over Voltage Protection .....................

Regulation .................................

Ripple .................. ...................

Fuses ......................................

Dimensions ................................

13.8 VDC regulated (adjustable).

20 amperes intermittent.
8 amperes continuoUs.

110 to 130 VAC, 6 amperes; or 220 to 260 VAC,
3 amperes; 50/60 Hz maximum.

Crow bar circuit will blow 20-ampere fuse if the A
output exceeds 15.5 volts.

Less than 2% from no load to 20 amperes.
Less than 1% at 20 amperes.

7-amp, 3 AG, slow-blow primary.
20-amp, 3 AG, output.

5-1/2" high x 9-1/4" Wide x 10-1/4 deep.
(13.97 cm H x 23.49 cm.W x 26.03 cm D).

23- lbs. (10.4 kg].

Net Weight ................................

W

The Heath Company reserves the right to discontinue
products and to change specifications at any time
without incurring any obligation to incorporate new
features in products previously sold.

CIRCUIT DESCRIPTION

The line voltage is coupled through fuse F1 and the
power switch in your transceiver to the power trans-
former. The power transformer steps the voltage
down from 120 VAC (or 240 VAC) to approximately
14 volts AC. This voltage is then rectified by bridge
rectifier BR1 and filtered by capacitors C1 and C2 to
provide a DC voltage. This voltage is then coupled
through Fuse F2 to the regulator circuit.

Transistors Q1, Q2, and Q3 form a Darlington-type
regulation circuit that provides high gain. Q1 and Q2
are in parallel in a series regulation circuit. The out-

put voltage from this circuit is controlled by the base
bias to Q3, which is provided by integrated circuit U1.

U1 has a zener reference diode built into it. This
integrated circuit samples the output voltage which is
coupled back through resistors R6, R5, R3, and R4,
and compares it to the internal reference voltage.
Then U1 automatically adjusts the bias voltage to Q3
so the output voltage will remain fixed. The sensing
voltage is taken from the load end of the power cable

so any voltage that is lost due to cable length is ac-
counted for.