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GPA10 Assembly Phase 3: Driver

Click Picture to Enlarge

Install resistors and a trimmer pot as shown here.

Install components as per photo.

Install inductor L1D and capacitors as per photo.
Note: The value of C11 is 180pF.

Install transistors TR1D, TR2D and TR3D.

The next step is to wind transformer T1D. Twist two 20cm lengths of 0.5mm enamel wire. Pitch: 2 to 3 turns per 1 cm.

Now feed the twisted wire. It passes 2 times through each binocular hole.

Pay attention to the orientation of leads, insert as per photo.

Assemble cable K3.

Note: centre lead of coax cable goes to middle pin and shield to side pins.

Bias adjustment: Remove cables K1 and K2. Attach temporary heat sink to driver mosfet TR3D. Power up the amplifier board.

Note: Since the cable K1 is disconnected, there is no voltage on L1D. which means that the bias voltage is ON. With trimmer RT1D set the voltage at point TP5 to +4,30V.

Turn the power off.
The next step is to install one permanent and two temporary jumpers.
The permanent jumper connects two pads on the layout of RL1C as shown below.
(RL1C is not installed, this relay is an option for further transverter upgrade).

Two temporary wires are to connect secondary of transformers T1D: one end to ground, other to REL2C, as shown here.

Re-connect cables K1 and K2.
Connect cable K3 as per photo: one end at amplifier end, connector SV1PA...

... and the second in the 3-pin header behind G59's antenna connector

Connect the antenna or dummy load to GPA10 board, antenna connector X1W.
Power up and transmit.
The output of GPA10 should read between 1 and 1.5W output.

This completes assembly of the driver stage.

"What can I do with a 1 watt output?"

Contrary to the opinion held by most amateur operators, one watt of output power on HF feed into a resonant, efficient antenna can do wonders! After completion of the driver stage of the Genesis GPA10 amplifier, I've decided to 'give it a go' on 40m. The local time was an hour past sunset and the forty meters band sounded reasonably good.

My first on-air attempt was on WSPR. ...

Genesis GPA10 Getting Started | Power Supply | Control Logic Circuit | The Driver | Output Amplifier | LP Filters

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