from 0 to 25 db in 1-db steps. The ATTEN IN / RF DIFF
2A1HY1J3) and the adjacent port (2A1HY1J4) will be
jack 2A1W6J5 and the ATTEN OUT jack 2A1W4J4,
isolated. By the same principle, if equal amplitude
together with the associated coaxial cabling and
quadrature-phased signals are applied to adjacent
connectors 2A1W6P3 and 2A1W4P2, respectively,
(e.g., 2A1HY1J2 and 2A1HY1J3), they will
make 2A1AT1 accessible at the front panel.
combine at one output port (2A1HY1J1) and cancel at
the other (1A1HY1J4).
Termination 2A1AT2 to
2A1HY1J4 is a 50-ohm matched load, and is provided to
5-9. Hybrid Coupler 2A1HY1
minimize reflected signal from port 2A1HY1J2.
a. Hybrid coupler 2A1HY1 is a four-port, 3-db
d. The sum channel overall insertion loss of the
coupler which evenly divides an input signal from
hybrid coupler from the RF SUM jack 2A1J2, to the RF
external test equipment into isolated quadraturephased
IN/OUT jack 2A1J1 is the sum of the losses of 2A1W1
outputs, for receiver testing of the IFF set. Front panel
db), 2A1HY1 (3 db) and
RF IN/OUT jack 2A1W5J1 provides the input to 2A1HY1
miscellaneous losses in 2A1J2, 2A1CP2, and the coaxial
and the RF SUM 2A1W1J2 and CPLR IN 2A1W2J3
cable terminated by 2A1P1 and 2A1J1.
jacks provide the outputs for receiver testing.
e. The difference channel overall insertion loss of
b. The hybrid coupler input signals, for IFF set
the hybrid coupler from the CPLR IN jack 2A1J3 to the
RF IN / OUT jack 2A1J1 is the sum of the losses of
2A2W1J2 and CPLR IN 1A1W2J3 jacks. The hybrid
2A1W2 (approximately 3.25 db), 2A1HY1 (3 db) and
coupler then combines the sum and difference RF
miscellaneous losses in 2A1J3, 2A1CP1, and the coaxial
signals into one resultant RF output. This RF output is
cable terminated by 2A1P1 and 2A1J1. These losses
available to external test equipment connected to the
when added to the losses of 2A W 3 and the 2A1AT1
front panel RF IN / OUT jack 2A1W5J1.
circuit (with the ATTENUATOR control set at 0) are
equal to or slightly less than the overall insertion loss of
c. The coupler is symmetrical, that is, signals applied to
the sum channel.
any input port (e.g., 2A1HY1J1) will divide equally
between the opposite pair of ports (2A1HY1J2 and