516F-2 AC Power Supply


The 516F-2 AC Power Supply provides all operating voltages for the Collins KWM-2/2A Transceivers and 32S-( ) Transmitters. It operates from a 115- or 230-volt, 50- to 400-Hz power source to provide high-voltage dc, low-voltage dc, variable dc bias, and an ac filament supply. The provided voltages are connected to the associated equipment by a 60-inch cable, and are terminated in an 11-pin female cable connector that mates with a male power receptacle located on the Collins KWM-2/2A Transceivers and 32S-( ) Transmitters. As supplied, the 516F-2 is factory-wired for 115-volt operation.


     Dimensions ...................  7-3/4 in high,
                                     9-7/8 in wide,
                                     11-1/2 in deep.

     Weight .......................  30 Lb.

     Ambient temperature range ....  0 to + 50  C.

     Input requirements  ..........  115 or 230 volts, 50 to
                                     400 Hz, 4 or 2 amperes.
                                     (Remove capacitor C1 when
                                     using a line frequency
                                     higher than 60 Hz.)

     Output voltages

     Heater power .................  6.3 +0.3 volts ac.

     Low-voltage B+ ...............  275 volts dc. Transmit
                                     NLT 250 volts dc; receive
                                     NMT 310 volts dc

     High-voltage B+ ..............  800 volts dc. Transmit
                                     NLT 690 volts dc; receive
                                     NMT 970 volts dc.

     Bias voltage .................  -55 to -80 volts,

Under the hood...

[Internal View]



Power transformer T1 supplies all voltages and current for the power supply outputs. T1 consists of two primary windings and five secondary windings. The two primary windings may be connected in parallel or series to accommodate either 115- or 230-volt primary power sources. Two of the secondary windings provide filament power to tubes V1 and V2; another supplies 6.3 volts ac to output power plug P1; a fourth winding supplies power to the 800-volt dc high-voltage rectifier circuit; and a fifth winding supplies power to the 275-volt dc low-voltage and -55 to -80-volt dc variable bias supplies.


The 800-volt dc high-voltage circuit consists of fullwave rectifier tube V1 and the choke input filter circuit consisting of L1, C2, C3, and C4. Resistors R1, R2, and R3 serve as voltage equalizing components, distributing equal voltages across C2, C3, and C4 respectively. Resistors R4 and R5 function as an output bleeder resistance to discharge capacitors C2, C3, and C4 when the power supply is turned off.


The parallel combination of L1 and C1 improves the regulation of the 800-volt dc output by automatically adjusting the effective filter network impedance as the load current changes. Under no-load conditions, the L1-C1 combination resonates at a frequency of 120 Hz, presenting a relatively large impedance to the 120-Hz ripple voltage. As the load current increases the current through L1 increases, decreasing the apparent inductance of L1 and therefore changing the resonant frequency of the L1-C1 combination. The higher the load current, the smaller the apparent inductance of L1 will be, causing an upward shift of the resonant frequency of the L1-C1 combination. This provides a lower effective impedance to the 120-Hz ripple voltage. With less 120-Hz ripple voltage dropped across the L1-C1 combination, more ripple voltage is delivered to the filter capacitor network (C2, C3, and C4), in turn developing more average dc output to the load. Capacitor C1 is removed when using a line frequency higher than 60 Hz.


The 275-volt dc low-voltage rectifier consists of V2 and the choke input filter system consisting of L2, L3, C5A, and C5B. Resistor R6 functions as a bleeder resistor to discharge capacitors C5A and C5B when the power supply is turned off.


The ac voltage for the -55- to -80-volt dc variable bias supply is obtained from the same secondary as the 275-volt dc low-voltage supply. The ac voltage is rectified by diode rectifier CR1 and filtered by C6, C7, R8, R9, and R10. Resistor R7 acts as a current-limiting resistor to protect diode CR1 during line voltage fluctuations and voltage spikes due to transients. BIAS ADJUST potentiometer R9 (a screwdriver adjustment) varies the dc output level as desired.


The outputs of the power supply and the primary switching leads are connected to pins of 11-pin female cable connector P1. This connector mates with the power plug on the associated piece of equipment. The ac line cord furnished with the 516F-2 is a 3-wire cord fitted with a 3-pin male plug for connection to the ac source. The round pin of the plug is connected to the power supply ground, providing protection for the operator in the case of possible component breakdown. If a 3-circuit outlet is not available, use the adapter plug furnished with the power supply, and ground the green wire that extends from the adapter.

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Copyright © 1996-WA3KEY & 1964-Collins Radio Company
This Home Page was created by wa3key, Saturday, April 20, 1996
Most recent revision Saturday, April 20, 1996