It has all been done before over 20 years back.? LT1252. It has essentially infinite input impedance. In this cct it is providing 5K input Z to the wiper of the potentiometer.? This chip can produce 50-60mW out at these voltages and at this load.? In this specific cct it drove the PA in class C to 4W RF.? There is no reason why the PA cannot be replaced by a 2n3866/4227 or any other "2W"? To39 RF? qualified transistor biased class A to produce 600-700 mW into a Trifiilar wound transformer, ie CT for use in a following class B stage.? This comes from a class of Video amps that will drive a +-5V signal into a 150R approx load given a 12V supply.? You can thank the great Dave Benson (SWL) for this cct but frankly a Chap called Breed used it some years before. again as? driver for a class C PA transistor. I respectfully suggest the OPT needs to be on a FB-61-202 core if you want good performance above 10 Mhz.? ? ?Take care with the component values on the schema. The leading decimal point is often meaningless.
Other devices / Sourcing?
An NE592 Will NOT work in such a circuit.? The LT1252 is out of production but still available out of SE Asia.? As Glenn? has pointed out to me the OPA2674 from TI is capable of even MORE and appears to be available on Ebay ex PRC? (but are they white spot chips from out back of the factory bin??).? ?A possible subs for the LT device (ie similar datasheet performance ) is the Max452CPA which Futurlec.com sell.?
