Ten-Tec JUPITER - Page 79

5. THEORY ОЕ OPERATION
This chapter introduces interested users to
a brief explanation of what goes on behind
JUPITER's front panel
5.1, Product Composition
JUPITER's basic design derives from the
Ten-Tec Model 550, but a number of
changes were necessary to replace
PEGASUS' personal computer functions
with front panel controls. Apart from the
software, physical, and cosmetic changes,
Ten-Tec engineers designed several new
electronic circuit board subassemblies to
transform PEGASUS to JUPITER.
Model 538 comprises the following
electronic subassemblies:
Subassembly
Description
Logic
RF
RF Power Amplifier
Low-Pass Filter
| Graphic Display
81899 Front Connectors
Rear Connectors
Table 5-1 Jupiter Subassemblies
Chapter 5 contains schematic diagrams
and parts lists for these assemblies. Refer
to them as necessary to follow the
explanations in this chapter.
5.2. Functional Overview
The 81886 Logic board connects directly
or indirectly to all other JUPITER
boards. Its principal functions are:
74269 Second Pprinting
JUPITER Model 538
30 August 2001
e All receiver and transmitter signal
processing, including multi-mode
modulation, demodulation and
filtering, between audio/data baseband
and the 3" IF stages;
e Control of all tuning operations,
including SPLIT, PBT, RIT/XIT;
в Non-volatile storage and recall of
control settings and VFO memories,
e Constant monitoring of all operator
controls to capture their status and any
changes for conversion to transceiver
control signals;
e Generation and control of all
information on the front panel display;
e Monitoring of several significant
analog signals from the transmitter and
receiver circuitry.
The 81889 RF board provides level
control and three frequency conversions
between HF and the 3" IF for the receiver
and 1-watt transmitter driver. It also hosts
the three local oscillators shared by the
receiver and transmitter.
The 81896 Power Amplifier works
exclusively in the transmit path where it
raises the low power level of the exciter
signal to as much as 100 watts output.
The primary function of the 81863 Low-
pass Filter board is to suppress harmonics
and mixer image products from the
transmitted signal, but it also includes the
high-speed transmit/receive switches and
detectors for monitoring forward and
reflected power to feed control functions.
The 81887 Keypad board hosts
JUPITER's front panel controls and the
28154 Graphics Display. Five rotary
shaft-to-digital encoders provide multiple
control functions with a traditional analog
feel. Twenty-six push-button keys
selectively activate or disable one-at-a-
5-1