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Guest on 16th August 2022 01:38:26 PM

RY1 - (117v AC coil) Relay used to power up the high voltage power supply. It can be energized with the DPDT center-off switch on the front panel of the supply in the "Local" position or with the H.V. rocker switch on the front panel of the 4-1000A amplifier with the DPDT center-off switch on the front panel of the supply in the "Remote: position. With the DPDT switch in its center off position, the supply cannot be powered up either locally or remotely.
RY2 - (240v AC coil) This relay is used to provide a delay in powering up the transformer, diodes, and filter capacitor for surge protection. When RY1 is energized, 240 volts AC is applied through RY2 but with the 50 ohm resistor in series with the transformer primary, regardless of the switch position. This resistor allows a lesser primary voltage to be applied to the plate transformer. Within a second, the voltage through the resistor cluster, is applied to the coil on RY2 which shorts the surge resistor and applies full voltage to the transformer primary.
The 2 pole, 3 position ceramic switch allows a varing amount of voltage to be applied to the primary of the plate transformer. The output voltages given here are without the amplifier keyed with only the bleeder resistor as a load.
Position 1, the Low position, applies half voltage (117 v AC from one half of the input circuit) through the full set of both primary windings in series. This provides approximately 1700 volts DC from the power supply.
Position 2, the Medium position, places the full 240 volts across both primary windings at the 141v tap. This provides approximately 3500 volts DC from the power supply.
Position 3, the High position, places the full 240 volts across both primary windings at the 117v tap. This provides approximately 4300 volts DC from the power supply.
One interesting fact is, when I originally built the amplifier and power supply, I drew off the schematics and built it from the scraps of paper. When I got ready to draw off the complete schematics, 35+ years later, I discovered an error in my design. The second relay, RY2, had originally been drawn breaking both side of the 240 volt primary. This did not allow the voltage to go through the surge resistor until the RL2 relay was fully energized and by that time, the resistor had been shorted. What I though was a time delay relay for surge protection was not working that way at all. By modifying the design and removing one switch pole of the relay, it allowed true time delay surge protection. Obviously, the surge protection was not as big a need as I thought but I still think it's a good idea and I now have that implemented.
Actually, once I had rewired the RY2 circuit, the resistor I had used (which was 375 ohms) was too large and the 220 volt relay was unable to get sufficient voltage to energize. I discoverd that 50 ohms was just about right and the delay from the time RY1 pulls in until the time RY2 pulls in to provide full voltage to the primary is about 1 second.

Raw Paste

RY1 - (117v AC coil) Relay used to power up the high voltage power supply.  It can be energized with the DPDT center-off switch on the front panel of the supply in the "Local" position or with the H.V. rocker switch on the front panel of the 4-1000A amplifier with the DPDT center-off switch on the front panel of the supply in the "Remote: position.  With the DPDT switch in its center off position, the supply cannot be powered up either locally or remotely.

RY2 - (240v AC coil) This relay is used to provide a delay in powering up the transformer, diodes, and filter capacitor for surge protection.  When RY1 is energized, 240 volts AC is applied through RY2 but with the 50 ohm resistor in series with the transformer primary, regardless of the switch position.  This resistor allows a lesser primary voltage to be applied to the plate transformer. Within a second, the voltage through the resistor cluster, is applied to the coil on RY2 which shorts the surge resistor and applies full voltage to the transformer primary.

The 2 pole, 3 position ceramic switch allows a varing amount of voltage to be applied to the primary of the plate transformer.  The output voltages given here are without the amplifier keyed with only the bleeder resistor as a load.
Position 1, the Low position, applies half voltage (117 v AC from one half of the input circuit) through the full set of both primary windings in series.  This provides approximately 1700 volts DC from the power supply.
Position 2, the Medium position, places the full 240 volts across both primary windings at the 141v tap.  This provides approximately 3500 volts DC from the power supply.
Position 3, the High position, places the full 240 volts across both primary windings at the 117v tap.  This provides approximately 4300 volts DC from the power supply.

One interesting fact is, when I originally built the amplifier and power supply, I drew off the schematics and built it from the scraps of paper.  When I got ready to draw off the complete schematics, 35+ years later, I discovered an error in my design.  The second relay, RY2, had originally been drawn breaking both side of the 240 volt primary.  This did not allow the voltage to go through the surge resistor until the RL2 relay was fully energized and by that time, the resistor had been shorted.  What I though was a time delay relay for surge protection was not working that way at all.  By modifying the design and removing one switch pole of the relay, it allowed true time delay surge protection.  Obviously, the surge protection was not as big a need as I thought but I still think it's a good idea and I now have that implemented.

Actually, once I had rewired the RY2 circuit, the resistor I had used (which was 375 ohms) was too large and the 220 volt relay was unable to get sufficient voltage to energize.  I discoverd that 50 ohms was just about right and the delay from the time RY1 pulls in until the time RY2 pulls in to provide full voltage to the primary is about 1 second.