for the RF FET, cooled with a heat pipe and a small CPU fan at half power.<\/p>\n\n\n\n
The power supply is a special blend of circuitry built around this:<\/p>\n\n\n\n
https:\/\/www.analog.com\/en\/products\/ltc7891.html<\/a><\/p>\n\n\n\n (The power supply FETs will be cooled with heat pipes as well.<\/p>\n\n\n\n Update 1:<\/p>\n\n\n\n Thanks to a winter storm giving me an extra day off, rev B is ready to order (Rev A was a failure because the FETs I selected were tiny BGAs beyond my ability to solder. Rev B uses equally modern FETs but in a friendlier package.<\/p>\n\n\n\n Simulations are complete. Power supply can ramp up or down over a volt per microsecond, and overall 90% efficiency is predicted. We’ll see! I was a little worried about coupling between L4 and L5 but the only effect when simulated (spice directive K1 L4 L5 0.2 or -0.2) was a small change in gain (which I can easily adjust elsewhere). Designed to fit in a 6″ x 4″ x 5″ enclosure with about 100 watts of active cooling (fills the remaining volume of the enclosure almost perfectly).<\/p>\n\n\n\n I left a clearance for heat pipes over the GaN FETs (both the power supply FETs and the RF amp FET). Those will go to a CPU cooler with a 92mm fan.<\/p>\n\n\n\n Update 2: <\/p>\n\n\n\n PCB: <\/p>\n\n\n\n https:\/\/www.pcbway.com\/<\/a> (click from here to get $5 off your 1st order and I get a few bucks off my next order)<\/p>\n\n\n\n Parts: <\/p>\n\n\n\n https:\/\/www.digikey.com\/<\/a><\/p>\n\n\n\n![\"\"](\"https:\/\/ai7sg.com\/wp-content\/uploads\/2024\/01\/revB.jpg\")
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Boards and parts are ordered, including the Type N to UHF adapters. 2 oz copper was a bit more expensive, but even with air flow there is just too much trace heating with 1 oz copper!
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