choke and the filter capacitors on the input of the unregulated power supply inverter. This L-C system is damped only by the high current regulator and is still oscillatory with even the normal inverter load.

The period of the L-C circuit is about 3 kc/sec which would indicate that turn-off of the SCR could occur within 150 microseconds after fault clearing.

From the foregoing it can be concluded that a high voltage flash-over during the launch phase would cause a heavy current load on the battery and that when the flash-over ceased, or the fault cleared due to component burn-out, an oscillatory current could be established which would promptly shut off the SCR. This action would allow the SCR's to be turned on again near impact.

B. CONCLUSIONS

As a result of this analysis, it is suggested that the following actions be considered:

1)

Increase the trigger-cathode shunting capacitor to 0.1 microfarad.

2)

3)

Consider using a transistor in place of the SCR, since sufficient base driving power exists in the trigger driving circuitry. Use a 30 ampere Westinghouse unit which has VCBO of 100 volts and a saturation resistance of 0.025 ohms, or a 2N3149-51 unit of 0.03 ohm at 50 amperes.

Eliminate the 100 microhenry choke, or move it to a position between the SCR and battery to protect the SCR's from excessive rate of application of full load current.

APPENDIX N

TV SUBSYSTEM LAUNCH READINESS

Ruling out the possibility of a failure to place the TV Subsystem in an operating condition at launch is considered to be justified, on the basis of its successful operation during considerable prelaunch activity. This included design bench testing, type approval testing, flight acceptance testing, system checks prior to AMR, and system status checks at AMR prior to launch. All this activity was concerned with the objective of developing confidence that the TV Subsystem would function properly in flight. As in the case of every other spacecraft subsystem and component, the assurance that the next turn-on will be successful exists in the form of an inferred statistical probability supported by the history of component performance during testing and performance checkouts.

The RA-6 TV Subsystem was subjected to extensive testing during assembly at RCAAED, during flight spacecraft system checkout at JPL, and finally during system checkouts at AMR. The significant phases of operation involved in a successful TV Subsystem

Separate portions of the overall checkout activity at JPL and AMR involving the TV Subsystem included:

These involve comprehensive checks of all system actions, commands, and responses; all subsystems are checked for proper operation.

1)

The TV Subsystem is operated in all modes (including full power turn-on); all command methods are checked (including the TV backup clock for the backup functions of the system).

2)

The TV Subsystem is checked both with and without collimators.