TM
FlexRadio Systems 2003 Page 9
Carrier is Very High on Transmit
Operational Description: The QSE, IC2 on the TRX board, provides quadrature
sampling of the I and Q signals at the carrier frequency. Any DC imbalance between the
four phases will cause a high level of carrier output. The QSD is biased to 2.5VDC by
the voltage divider made up of R7 and R22. Worst-case carrier output with no
modulation should be –25dBm (-55dBW).
Probable Causes: The primary cause is a failure of IC2 on the TRX board. Remove the
BPF board for this test. Check the voltage at the common point between R7 and R22 in
transmit mode. It should be 2.5VDC +/- 0.1V. If it is well outside of this range in
transmit mode, IC2 is damaged and must be replaced.
The LM7805 (IC5) Heat Sink on the PIO Board Gets Very Warm,
Possibly Causing the Radio to Temperature Cycle.
Operational Description: The PIO board uses LM7805 (IC5), 5V linear regulator, to
generate 5VDC from the 13.8VDC supply. IC9 and IC10 regulate the 5V supply down to
3.3V for powering the AD9854 DDS, which dissipates around 2W. All relays on the
BPF and TRX board are also powered from the 5V supply. Although a linear supply
provides the lowest noise power solution, heat dissipation without forced air-cooling may
be a problem in some installations. Outside of an enclosure at room temperature, the heat
sink plate will run about 60C. The DDS chip, IC4 on the TRX board, will run over 70C
under the same conditions.
Probable Causes:
1. Metal jackscrews on the bottom of the PIO heat sink plate should mount directly
to a BARE metal on the enclosure with heat sink grease applied to the point of
contact. This will help significantly in the transfer heat into the enclosure.
2. Make sure there is proper airflow across the PC board stack. It may be necessary
to install forced air-cooling. The SDR1K-ENC has provisions for the installation
of a 80mm fan.
The LCD Fonts are not Displayed on the SDR-Console
Operational Description: The SDR-Console frequency displays are best viewed with
the TBLCD font that may be retrieved from the link under the Software section on the
FlexRadio Systems Download page. Install the font according to the SDR-Console
Installation and Quick Start Guide.
Where are the SDR-Console Registry Entries?
Operational Description: All Setup Options as well as the state of the radio when
turned off are stored in the Windows Registry under:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\SDRConsole
If for some reason erroneous data gets stored in the Registry you can delete the
SDRConsole folder and it will be recreated on the next startup with the default values.
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