Revision 1.0
11
Copyright FlexRadio Systems, 2010-2011
Alignment, Test and Calibration
The only manual alignment required is setting the quiescent bias for the RF power
transistors on the RFPA (PPA05 PCB.)
All other alignment, test and calibration will occur under computer control using
production test software built into PowerSDR.
Bias Adjustment
FLEX-1500 RFPA (PPA05) Bias settings
==
Power Supply Setup:
Adjust Power Supply to 13.8 Volts Output Voltage.
Adjust Power Supply maximum current limit to 2.5 Amperes. To do this, place a short
across the output terminals of the power supply and adjust the Output Current knob to
read 2.5 Amps on the current meter.
==
The Bias settings are normally set with the PA board out of the radio. It does not have to
be connected to the TRX board, since it is all DC settings, and you do not want any RF
drive present.
With just the PA by itself on the workbench...
Plug in +13.8 Volts into the normal power connector.
To turn on the PA bias, ground the test point named "XMIT" at the lower right corner of
the board, between K8 and K15. This will also activate relay K15, so you will hear a
"click."
To measure current in the driver transistor, there is a one Ohm shunt resistor between test
points DM- and DM+. Put a voltmeter that will give good readings in the range of 50
milliVolts across these two test points. Normally you would adjust R8 for 50 milliVolts
plus or minus 5 milliVolts corresponding to 50 milliAmps flowing through driver
transistor Q1.
(Warning: do not use long test probes that will go all the way through the PC board and
touch the plate below. This will short the +13.8 Volts to ground and/or destroy the
metering resistor R2.)
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