Upconverter; Figure D-2 Functional Block Diagram Of The Upconverter Section - Comtech EF Data CSAT-5060 Installation And Operation Manual

CSAT-5060 50 Watt C-Band Transceiver
Theory of Operation
D.1.2 U
PCONVERTER
The RF input to the upconverter is at 70 ± 18 MHz at a typical level of -35 dBm
which would provide an output power back-off of 8 dB. In operation, the input
signal is mixed up to the 1250 MHz IF in the first conversion mixer operating at a
fixed frequency with low side LO injection at 1180 MHz provided by the
upconverter IFLO. IF filtering is provided by the 1250 MHz BPF. It is just wide
enough to pass the 36 MHz bandwidth of the desired signal while maintaining
more than adequate amplitude and group delay flatness. At the same time, it is
narrow enough to provide the necessary rejection to any unwanted mixer
products, the IFLO, and other spurious signals.
The second mixer up converts the 1250 MHz IF signal to the desired output
frequency. It uses low side LO injection in the 4595 to 5175 MHz frequency
range provided by the upconverter RFLO in 1.000 or 2.500 MHz steps. Both step
sizes are automatically selectable. The upconverted signal is then filtered to reject
the RFLO leakage, and any other unwanted mixer spurs at the mixer output. The
output signal is then amplified by a series of internally matched power FET's to
raise the power level of the output signal to the specified level. An isolator is
provided at the output of the high power output stage to protect it from
mismatches at the output connection to the antenna feed.
70 +/ - 1 8 M Hz VA R
ATTEN
CO M M & C 10 M Hz
REFERENCE

Figure D-2 Functional block diagram of the upconverter section

VA R
ATTEN
1 2 50 M Hz BP F
11 8 0 M Hz
IFLO
11 8 0 M Hz
D-3
MN/CSAT506050.IOM
SSP A
RFLO
PO WER
5 17 5 -
SUP PLY
5 47 5 M Hz
Revision 0
2 5 WA TTS
64 2 5 - 6 72 5 M Hz