25-200MHz / 8-45W AMP ***************************************************************************** --------------------O input | D1 __ | *-------|>|---- --)|-- | R2 -- | C1 | R1 *---/\/\/-----*----------|-/\/\/--- | ^ | | | C2 | R3 | | *--)|-*----/\/\/----*----- | | | | | / | | \ | | / R4 | | \ | | | g | | Q1 ----- | | ----- | | s| ^ |d L1 | *-------------------|_| |-*-(()((-* | < C3 L2 | | *-----)|---*-------(()((--| C5 | | | --)|--* | | > output | C6 | | --|(----O -----)|--* | C4 |-----| | -------------------- --- | - +12-24V ***************************************************************************** SchemAsciit(r) (skem-as-kit) Symbols Key ======================================== > g -|(- = trimmer capacitor ----- ----- = RF power transistor -|(- = capacitor | ^ | g)ate s)ource d)rain s|_| |d -/\/\/- = resistor * = connection point -(()((- = coil __ --|-- = jump (not connected) -|>|--- = Zener diode ___ -- _ = ground Component Listing ================= R1 - 2.5K ohm L1 - 5 turns, #18 varnished, R2 - 20K ohm trimmer potentiometer 5/16" inside diameter R3 - 68 ohm R4 - 10 ohm L2 - 3 turns, #18 varnished, C1 - 220pF Tantalum, 35 volt 5/16" inside diameter C4 - 16-100pF trimmer capacitor C2,C6 - 4.7uF Tantalum, 35 volt D1 - 1N5230 (4.7V Zener diode) C3 - 8-50pF trimmer capacitor C5 - .1uF ceramic disc capacitor, 50 volt Q1 - (see chart) Transistor Data (input --> output watts at 100MHz, 24 and 12 volts) =============== PART # IN OUT IN OUT ------ ---- --- ---- ---- MRF134 - 0.4W --> 8W || 0.6W --> 3.5W MRF136 - 0.4W --> 19W || 0.6W --> 8.5W MRF137 - 1.0W --> 45W || 1.0W --> 17W MRF138 - 1.5W --> 45W || 1.5W --> 15W [24V] [12V] * ASSEMBLY: Watch it with static around the TMOS transistor. It is VERY sensitive. If there's any static voltage difference between the drain or gate and the source, you can toast it! Keep it in the static-proof bag in which it was shipped until you're ready to install it as the LAST component. Then solder the source tabs first, then the gate (opposite diagonal tab) and drain (diagonal) tabs. (See diagram:) S /\ __ D \ \___/ / /====\/MRF\/====\ | O | 137 | O | <--- mounting flange \====/\___/\====/ / / \ \ G \/ \/ S Mount the TMOS flange to a metal box with some heatsink compound. Ground your PCB to the same cabinet. * TESTING: Connect the output to a dummy load which can handle the power level you'll be generating. Set the trimpot at mid-range and apply your 12 or 24V. At this point, the power transistor shouldn't get warm until you turn the pot up more. If it does start to warm up, turn the pot down a bit until the temp. remains the same or lowers. DO NOT adjust past this point. Now feed your RF signal to the amp's input. Use C3 (tuning) and C4 (load) to adjust for max. output. You may also have to readjust R2 for the best reading. Keep and eye on the meter for sudden jumps in output - this shouldn't happen. * TROUBLESHOOTING: If tuning is erratic, the amp is probably going into self- oscillation which can be caused by insufficient grounding, bypassing of the power supply leads, too long of input or output wires, or too high a bias. * PARTS: Contact "RF Parts" at 619-744-0728 for the transistor you choose. Ask 'em for their latest flyer, too. It's free. Your local electronics supplier other than Smack Shack ought to have everything else you'll need (at least mine does!). If not, try "Mouser Electronics" at 800-346-6873 and get their free catalog, too. Well, I tried... :) If there's some discrepancy about this lousy schematic representation, or anything else for that matter, E-Mail me at: cdimick@esunix.sim.es.com I'll try to clear things up for you. It works like a charm for me, albeit a little hot. Good luck! (BTW - The complete plans including schematic, PCB layout, and detailed assembly instructions are available from Panaxis Prod. P.O. Box 130, Paradise, CA 95969. No copyright was listed on the plans, so I copied what little I could tolerate for you folks.)