[Heathkit] Heath Power Supply HP-23B

[Ray]

I have a question for anybody who might know the answer...
Just picked up a Heath Power Supply HP-23B

The question is....The AC power switch is labeled as follows...

Left Position:        
LV
250DC

Right Position:
LV
300DC

What is the difference between the 250 & 300 setting
Which position should be used with HW-101?
And what does LV Mean...

I have no manual available at this time...

Thanks,
73
Ray, N6XVO