It sounds to me as though you have a Lansing 285, the large format compression driver with the radial slit phasing plug. Is this the case?

The ratings stamped into the metal badge would be for DC voltage operation of the field coil. 220VDC was the most common field supply voltage for these drivers, being used routinely in the Lansing Shearer Horn systems. 25 watts dissipation in the field coil is also correct for these drivers. Field coils were also wound for other supply voltages, so you should be sure before applying voltage.

I have a couple of 285 drivers in my collection rated to run on 220VDC. Their field resistance measures about 2,500 ohms.

Calculating the correct supply voltage when the DC resistance and dissipation is known is an Ohm's Law calculation. Please contact me here or at stfrsc@juno.com if you would like assistance with this.

• Lansing 285