225 Lb - 2,800 VDC @ 2 Amps Continuous (Variac adjusts filament voltage)

One of the least difficult and most expensive portions of any RF amplifier is the power supply. This is due, in large part, to the expense of locating and purchasing a suitable high voltage transformer. To offset the cost, many builders attempt to build a doubler, or tripler circuit around a less expensive transformer, only to discover that the supply provides poor regulation and insufficient current to properly power the amplifier they worked so hard to build. Such "economy" power supplies do have a place, particularly when the intended power out is under a KW. Nevertheless, I have provided in this section circuitry utilizing both routes. In addition, I recommend that the builder study a bit about hv power supplies before attempting construction (see *Reference Material for suggested titles).

Below is a voltage doubler circuit, well suited for smaller, compact linear amplifiers. For a full size image that may be printed, simply left click on the circuit image; when the enlarged diagram comes up right click on it, select "Save Picture As", select a location and save the image, and click on the "Back" button on the browser to return.

The power transformer, T1, may be a 800-1000 volt unit capable of providing at least 800 ma. A safe bet would be a transformer capable of those voltages, weighing more than 10 pounds. Care must be taken not to attempt to exceed rating of the parts utilized.

The diodes, equalizing resistors and corresponding capacitors may be mounted on an etched or simple perf board. Ceramic or bakelite standoffs provide the necessary insulation and make mounting the board relatively simple. When assembling the capacitor stack, attention must be given to the fact that voltage will be present on the outside of the "cans" and each must not only be insulated from each other, but from ground as well. Placement of the swamping resistors that straddle the caps should have adequate ventilation. Additional information on construction of the voltage doubler supply is provided below. Select "NEXT" to continue.