I'm using the LTC6907 (http://cds.linear.com/docs/Datasheet/6907fa.pdf ). I use a circuit similar to figure 13. In my application, I am running at 2.3MHz and need to deviate 75kHz. I put 200 ohms between the low side of the set resistor and ground, then have another resistor driving the top of the 200 ohms. The other side of that resistor is where my control voltage goes. Harold -- FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist