PA Driver Introduction


The upconverted RF (from the modulated AF I and Q signals' processing in the Store and Hold Mixer) is passed via the mixer's input/output line to the driver 2N2866 and, thence, to the IRF510 FET PA, and on through the low pass filters, to the antenna. .

PA Driver Schematic

PA Driverschematic

PA Driver Bill of Materials

Stage Bill of Materials

(resistor images and color codes courtesy of WIlfried, DL5SWB's R-Color Code program)

1Magnet wire, enameled #20Copper magnet wire for coilsPA Driver
11 k 1/4W 1%br-blk-blk-br-br br-blk-blk-br-br1/4W PA Driver
310 ohm 1/4W 1%br-blk-blk-gld-br br-blk-blk-gld-br1/4W PA Driver
1100 1/4W 1%br-blk-blk-blk-br br-blk-blk-blk-br1/4W PA Driver
11R 1/4W 1% (1R)brn-blk-blk-silver-brn brn-blk-blk-silver-brn1/4W PA Driver
2330 1/4W 1%ora-ora-blk-blk-brn ora-ora-blk-blk-brn1/4W PA Driver
1330 1/4W 1%ora-ora-blk-blk-brn ora-ora-blk-blk-brn1/4WPhase 8: Marked on pcb as 470nH PA Driver
1390 1/4W 1%ora-whi-blk-blk-brn ora-whi-blk-blk-brn1/4W  PA Driver
1470 1/4W 1%yel-vio-blk-blk-brn yel-vio-blk-blk-brn1/4W PA Driver
168 1/4W 1%blu-gry-blk-gld-brn blu-gry-blk-gld-brn1/4W PA Driver
2BN43-202 binocular core PA Driver
110 nF (.01uF)103 103Ceramic PA Driver
7100 nF104 104ceramic PA Driver
147 uH molded inductoryel-vio-blk-gld yel-vio-blk-gldchoke PA Driver
1M3 screw and nut setHDW PA Driver
13.5mm stereo jack - PCB mountjack PA Driver
2shunt wire (cut-off lead)misc  PA Driver
1TO-220 heatskinkmisc PA Driver
1TO-39 heatsink miscPA Driver
1Power MOSFET IRF510IRF510 IRF510TO-220 PA Driver
12N3866 NPN Transistor TO-39 PA Driver

PA Driver Summary Build Notes

PA Driver Detailed Build Notes

Bottom of the Board

PA Driver Bottom View

Top of the Board

PA Driver Top View

Install All Components, Except FET and Transformer

Install All Components, Except FET and Transformer photo
E23110 nF (.01uF)103 103Ceramic
E201100 nF104 104ceramic
E204100 nF104 104ceramic
E225100 nF104 104ceramic
E232100 nF104 104ceramic
E237100 nF104 104ceramic
E333100 nF104 104ceramic
E334100 nF104 104ceramic
R5147 uH molded inductoryel-vio-blk-gld yel-vio-blk-gldchoke
R641R 1/4W 1% (1R)brn-blk-blk-silver-brn brn-blk-blk-silver-brn1/4W
R10010 ohm 1/4W 1%br-blk-blk-gld-br br-blk-blk-gld-br1/4W
R4910 ohm 1/4W 1%br-blk-blk-gld-br br-blk-blk-gld-br1/4W
R5310 ohm 1/4W 1%br-blk-blk-gld-br br-blk-blk-gld-br1/4W
R10168 1/4W 1%blu-gry-blk-gld-brn blu-gry-blk-gld-brn1/4W
R69100 1/4W 1%br-blk-blk-blk-br br-blk-blk-blk-br1/4W
R50330 1/4W 1%ora-ora-blk-blk-brn ora-ora-blk-blk-brn1/4W
R52330 1/4W 1%ora-ora-blk-blk-brn ora-ora-blk-blk-brn1/4W
R92330 1/4W 1%ora-ora-blk-blk-brn ora-ora-blk-blk-brn1/4W
Phase 8: Marked on pcb as 470nH
R46390 1/4W 1%ora-whi-blk-blk-brn ora-whi-blk-blk-brn1/4W 
R48470 1/4W 1%yel-vio-blk-blk-brn yel-vio-blk-blk-brn1/4W
R681 k 1/4W 1%br-blk-blk-br-br br-blk-blk-br-br1/4W
E206TO-39 heatsink misc
E3042N3866 NPN Transistor TO-39
E823.5mm stereo jack - PCB mountjack

Wind and Install the Dual Binocular Transformer

Glue the Cores

Glue together the two binary cores as indicated in the graphic, below:

Twisted Wire
  • Prepare a 40 cm (~16") long piece of enameled copper wire and fold it over so that it is two 20 cm wires joined at the one end
  • twist the wires together so that you get approximately three twists per 10 mm (~0.4") of length
Wind the Wire through the Cores
  • (Refer to the numbered holes in the cores on the above graphic)
    Thread the twisted wires (folded end first) through the glued cores, starting in hole 1, coming out the other end and looping back through the top core to exit at hole 3. Continue from hole 3 into hole 2, coming out the other end and looping back into the upper core so as to exit at hole 4. .
  • When finished winding, cut the folded end of the twisted wire off, such that you now have four wire ends.
  • The pair at hole 1 represents the primary leads (a and b); the pair at hole 4 represents the secondary leads (a1 and b1) of the wound transformer.
  • Using an ohm meter, identify the ends of each wire as indicated on the graphic above. You may want to use a small piece of colored hookup wire insulation to identify the "a - a1" (or, if you prefer, the "b - b1") wire's ends.
  • Testpoint Units Nominal Value Author's Yours
    a - a1Ohm00_______
    b - b1Ohm00_______
    transformer continuity
Mount the Transformer
  • You do not need to worry how to figure out the phasing; if you match the designated leads (a1, b1, a, b) with the holes as marked in the graphic below, you will have correct phasing.
  • Insert transformer's leads into the PCB holes, as indicated above. Form the leads and pull them tight. Then cut off the excess (on the underside of the board) so that approximately 5mm (1/8") of wire is protruding out on the underside of the board.
  • Remove the transformer from the PCB, scrape the enamel coating from the 4 leads but DO NOT TIN them as yet (tinning the leads could cause them to be too "fat" to go back into the holes).
  • Insert the 4 transformer leads back into the PCB and solder them.

E198BN43-202 binocular core
E198aBN43-202 binocular core
MWMagnet wire, enameled #20
Copper magnet wire for coils

Install FET and Heat Sink

Attach the IRF510 power MOSFET to its heat sink with the M3 screw and nut. Then solder the IRF510 leads and the two heat sink pins, such that the Transistor side of the heat sink is facing "north" and the blank side of the heat sink is facing "south".

Install FET and Heat Sink photo
E196Power MOSFET IRF510IRF510 IRF510TO-220
E219TO-220 heatskinkmisc
hdw1M3 screw and nut setHDW

Install two Jump Wires

Using two pieces of cut-off component lead wires, solder jumper wires as indicated below

Install two Jump Wires photo
jmp101shunt wire (cut-off lead)misc 
jmp102shunt wire (cut-off lead)misc 

Install Remaining Permanent Vtx Wires

Install the permanent wires that provide Vtx routing (click here for a high-resolution view of the graphic).:

  • C-C (endpoints marked "C")
  • D-D (endpoints marked "D")
  • G-G (endpoints marked "G")
  • H-H (endpoints marked "H")
  • I-I (endpoints marked "I")

Install Remaining Permanent V<sub>tx</sub> Wires photo

Install Final Permanent Wire

Install wire J-J (endpoints marked "J")

Install Final Permanent Wire photo

PA Driver Testing

No Tests at this Point

Test Setup

Tests are performed in the final stage after all needed wires are installed/checked.

Click here to review final layout of wires and switches