Operation & Service Manual
Section III
Model 1805B RF Control Unit
Theory & Operation
Figure 3-2 Controls and Indicators (Rear)
The ADDRESS switch contains seven small switches that are numbered from left to
right; however, only switches 1 through 5 are used for selecting the unit address. Switch
1 is the least significant bit (LSB). Addresses 0 through 30 are valid. Address 31 is
invalid. Figure 3-3 is a view of the ADDRESS switch showing the switches' numbering
scheme. Also included is a truth table that lists switch 1 through 5 positions (0 or 1) for
addresses 1 through 10,20, and 30.
To code a particular address, set switches 1 through 5 to either ON (push top of switch
in) or OFF (push bottom of switch in) to code a binary 1 or 0, respectively. Notice that
when the ON position is selected, a red band appears in the ON position.
OPERATING INSTRUCTIONS
The Model 1805B RF Control Unit was primarily designed as one component of the
TEGAM System IIA whose purpose is to accurately transfer the calibration factors
of NIST standards to feedthrough and terminating bolometer mounts, thermistor mounts,
and power sensors. The following paragraphs provides general operating instructions for
the Model 1805B such as Initial Power-up and checkout procedures. Manual operating
Instructions, IEEE-488 Bus operation and a overview of using the System IIA
Windows™ (SureCAL) Software with the Model 1805B. More detailed operating instruc-
tions and application information for the various System IIA configurations can be locat-
ed in the System IIA Automatic Power Meter Calibration System operation and Service
Manual (IM-198).
Figure 3-3 Address Switch
INITIAL POWERUP AND CHECKOUT PROCEDURES
After performing the installation instructions in Section II and all system cabling has
been connected as desired, apply power to the 1805B as follows:
3-5
Switch Number 1 2 3 4 5
Decimal Weight 1 2 3 4 5
Address:
0
0 0 0 0 0
1
1 0 0 0 0
2
0 1 0 0 0
3
1 1 0 0 0
4
1 0 1 0 0
5
1 0 1 0 0
6
0 1 1 0 0
7
1 1 1 0 0
8
0 0 0 1 0
9
1 0 0 1 0
10
0 1 0 1 0
20
0 0 1 0 1
30
0 1 1 1 1
Address Truth Table
ADDRESS
SWITCH
