For best efficiency and amplifier performance: use a resistor as the RF load.
Kevin - if you try to keep things legal you will get a lot better help here. There are folks here who know how to get 200-500 feet range without breaking the law. If this device has a commercial purpose, apply for an experimenter's permit. I's nearly free, and lasts 2 years
- form 442 with the FCC ... assuming you are in the USA.
Frank Raffaeli