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10W HF Linear PA kit assembly

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10W HF Linear PA

10W HF Linear Power Amplifier kit assembly manual

A low-cost, high-performance HF Linear PA

covering 2-30MHz

Designed and produced by QRP Labs, 2018

Summary of Contents for 10W HF Linear PA

Page 1: ...10W HF Linear PA kit assembly 1 00 1 10W HF Linear PA 10W HF Linear Power Amplifier kit assembly manual A low cost high performance HF Linear PA covering 2 30MHz Designed and produced by QRP Labs 2018...

Page 2: ...R209 R210 19 3 14 Install resistors R201 R216 and R217 20 3 15 Install resistors R207 and R208 20 3 16 Install resistors R213 and R218 21 3 17 Install resistors R212 and R214 21 3 18 Install resistor...

Page 3: ...lifier for beta testing prototypes measurements and moral support 2 General Assembly guidelines Assembly of this kit is quite straightforward But there are quite a lot of components So please keep the...

Page 4: ...need to allow extra time with the soldering iron Ground pads are separated from the groundplane by what are called thermals a gap between the pad and the groundplane which is bridged in 4 places at 0...

Page 5: ...U9024 substitute for BS250 2pcs Q207 208 IRF510 2pcs IC201 78L05 5V voltage regulator Inductors L201 BN43 2402 binocular core L202 L203 L204 L205 1uH molded axial inductors T201 202 BN61 2402 binocula...

Page 6: ...10W HF Linear PA kit assembly 1 00 6...

Page 7: ...There are only two layers nothing is hidden in the middle Not shown in these diagrams are the extensive ground planes on both sides of the board Practically everything on both layers that isn t a RED...

Page 8: ...10W HF Linear PA kit assembly 1 00 8...

Page 9: ...10W HF Linear PA kit assembly 1 00 9 3 3 Schematic...

Page 10: ...s that could cut into the wire L201 is a simple inductor made of 4 turns of the 0 4mm Medium thickness wire wound around the BN43 2402 binocular core One turn means the wire goes through both holes Th...

Page 11: ...ist the other in a VERY LOW speed drill or using an electric screwdriver Or just apply twists by hand this is the method I use The number of twists is not critical and it will not be the end of the wo...

Page 12: ...and C wires which would indicate a short circuit somewhere in the wiring perhaps caused by a break in the enamel insulation When completely happy cut the wires to 2mm below the PCB and solder them al...

Page 13: ...ous section let us identify the bifilar windings as A and B and the single wire winding as C Again untwist the bifilar winding ends and identify the pairs of wires with the DC continuity test Be sure...

Page 14: ...C winding and the A B windings You should not see a DC zero resistance continuity between any A B to C test points On the other hand A and B test points will show DC continuity between each other sin...

Page 15: ...wires check again very carefully with a DVM touched to the wire ends that you have continuity between the two pairs of points as indicated by the orange lines Only when you are totally sure the four w...

Page 16: ...r that each 1 turn means the wire passes through both holes of the binocular core So push the wire through to the left end and then back through the other hole to the right then the same again for the...

Page 17: ...hick wire also absorbs heat easily so be sure to hold the soldering iron on the joint for at least 10 seconds to be sure of a good connection The 3 turn output winding can be checked for DC continuity...

Page 18: ...00 18 3 10 Install capacitors C211 and C212 These two capacitors are 1uF ceramic capacitors with label 105 3 11 Install remaining ceramic capacitors The remaining 10 ceramic capacitors are all 0 1uF c...

Page 19: ...ded inductors One lead is to be bent over so that they are mounted vertically like the resistors 3 13 Install resistors R203 R204 R209 R210 These are 220 ohm 0 5W resistors They have colour code red r...

Page 20: ...re 220 ohm resistors with colour code red red black black brown Be careful with the identification of resistors on this PA PCB because lots of them start with colour code red red 3 15 Install resistor...

Page 21: ...y 1 00 21 3 16 Install resistors R213 and R218 These are 10K resistors with colour code brown black black red brown 3 17 Install resistors R212 and R214 These are 47 ohm resistors with colour code yel...

Page 22: ...near PA kit assembly 1 00 22 3 18 Install resistor R202 R202 is a 22K resistor colour coded red red black red brown 3 19 Install resistor R205 R205 is a 2 2K resistor with colour code red red black br...

Page 23: ...l resistor R206 R206 is a 33 ohm resistor with colour code orange orange black gold brown 3 21 Install trimmer resistors R211 and R215 These are trimmer resistors with code 472 Rotate the trimmer pote...

Page 24: ...or is orientated correctly as per the PCB silkscreen The long wire is positive and must be inserted in the hole marked 3 23 Install capacitor C214 C204 is a polarized 470uF electrolytic capacitor As p...

Page 25: ...e stripe end next to the PCB in the left of the two holes and bent over wire end non white stripe end in the right of the two holes This makes sure the bent over wire is not next to the washer of the...

Page 26: ...es shown on the PCB silkscreen When the transistors are lying with their flat faces flush against the PCB and they are not obscuring the hole drilled in the PCB in their center you can solder them in...

Page 27: ...or matching the flat drawn on the PCB silkscreen 3 29 Install voltage regulator IC201 IC201 is a 78L05 Voltage regulator IC in a TO92 package It looks similar to a BS170 transistor so check carefully...

Page 28: ...y get ONE chance at this if you bend them the wrong way and you try to bend them back to correct it the wires will snap off The following three photographs all show the IRF510 with the leads bent corr...

Page 29: ...ttom view should look like this before attaching the heatsink The top view of the completed PA board looks like this Note here the board is shown mounted on the heatsink by three nuts one on each of t...

Page 30: ...the heatsink 1 Cut the blue silicone insulating pad so that it is shaped as shown 2 Place the pad on top of the PA BS170 transistors Q202 Q203 and Q204 3 Thread the large washer onto the 15mm M3 bolt...

Page 31: ...0 driver heatsink assembly should all line up perfectly with their respective holes in the heatsink This heatsink is custom designed to fit the QSX PCB assembly perfectly 9 Now tighten all the bolts M...

Page 32: ...has been performed and all screws are tightened 5 Always use a Low Pass Filter between the Amplifier output and your antenna system 6 On first powering up the amplifier and during adjustments use a cu...

Page 33: ...ase in current consumption of 125mA Once both PA transistor bias has been adjusted for 125mA total 250mA this sets up the Linear Power Amplifier for optimal performance operation 4 4 Tests undertaken...

Page 34: ...gain is down by 4dB compared to HF 4 Gain is 8dB down at 70MHz 4m band compared to HF 5 With sufficient drive the amplifier is capable of producing 20W output at 13 8V supply using 15dBm input over th...

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