Voltech AT5600 User Manual page 128

C H A P T E R 7 – T E S T S
3) FCC 68.310 method (used in USA
The source and load resistors (and the fixture transformer for the IEEE and FCC
methods) are assumed to be on the fixture but are not shown on the Editor
schematic. They are switched in circuit using an OUT test that must be inserted in
the program before the GBAL test. (The relay patterns associated with inserting
and removing fixture resistors have deliberately not been included in the GBAL
test dialogue for two reasons: a) it would make the dialogue too complicated, and
b) it is not always necessary - e.g. in the case of a fixture where the resistors are
permanently fitted in circuit).
After the two measurements, have been taken, the longitudinal balance is
calculated from the ratio of the two outputs:
GBAL =
Please also see
14.6.15 for specific advice on programming the test, and
10.2.19 for test accuracy specification
AT5600 User Manual 98-119 issue 14
A N D T E S T C O N D I T I O N S
Measurement
Energized
Hi Lo
1 A B
2 A B
20 log | VM1 / VM2 |
+ (optionally) compensation for test fixture scaling
Measured
Hi Lo
C D
E F
Page 128