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Solder a wire
STEP 4: Fastening of the LDMOS transistors: after properly cleaning the plate surface, smear a thin layer
of silicone fat on the lower side of the flange of the MOSFETs, fasten them to the heat sink and solder the gate
first, then the drain. Solder the two 13pF (ATC) chip capacitors and above them the two 1-5pF capacitive
trimmers, between the two pair of gates, as shown by the mounting plan.
STEP 5: Connect serially a c.c. amperometer to the power supply, with scale starting from more than 5A (i.e. 10A).
STEP 6: Power the module and check the MOSFET is not absorbing current; this means that the device is
integral and working correctly.
STEP 7: Slowly turn the R7 trimmer until the MOSFET absorbs 1A, always checking that there are no self-oscillation; under
this conditions it is possible to check by means of a digital tester that the voltage on the gate is about 5.2-5.4V.
STEP 8: Repeat the previous step for the other section of the module, this time turnign R8 and checking that the indication of
the current on the amperometer increases to 2A total (which includes the current of the other device left on).
STEP 9: Check the response curve of the module by means of the network analyser.
STEP 10: Check the response curve for low signal with centre 660MHz and span 500MHz, 2dB/div.
STEP 11: The curve should be similar to the one enclosed, with a tolerance of ± 0.5dB. To obtain this, act on
the four trimmers C41-C41a and C42-C42a with the proper "calibrator", inorder to flatten the curve as much
as possible, especially at the edged of the band which represents the minimum values.
STEP 12: Finally, check that the current in stand-by does not increase by more than 15÷20%, reaching at
worst 2.3÷2.4A when the heat sink is hot and not ventilated.
Note: when mounting-removing the PALLET on the heat sink, tightly fasten the screw of each all "N" input and output
connectors. These are mounted with a single 3mm screw and if it is not properly fastened it may be detached from the PCB
by a movement of the connector once it has already been soldered to the path.
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