Paradise Datacom HPAC-100-RM, Operation Manual

Page: 55 / 80

Operations Manual: HPAC-100/125/150/200/250-RM SSPA 5-1
5 Performance Tests
Introduction
This section describes some of the standard RF tests performed on the unit before
shipment.
RF Specification Tests
Gain and Gain Flatness
The unit gain is swept over the operating frequency range under small signal condi-
tions to confirm the minimum gain and flatness specifications. The RF module is
also taken to the temperature extremes and again measurements are taken to verify
that the specifications are met.
1 dB Gain Compression Point
The 1 dB gain compression point is measured at discrete frequencies across the
band to characterize the output power over the operating frequency range. It indi-
cates the point at which the nonlinearities of the transistors cause a 1 dB decrease
in the expected output signal. These measurements are taken at room temperature
to meet specification, but they are also measured at the temperature extremes to
ensure proper operation.
Input and Output Return Loss
The input and output return losses indicate how closely the amplifier is matched to a
50 Ohm system. The return loss is easily translated into input and output VSWR by
the following equation:
A return loss of infinity or a VSWR of 1 indicates a perfect match to a 50 Ohm sys-
tem. Having mismatches in a system increases the system losses which translates
into lower output power and in severe cases, damage to equipment. Frequency
swept plots of the return losses are taken.
Spurious
Spurious signals are undesirable byproducts of amplifiers caused by nonlinearities
within the amplifier and other system level components such as switching power
supplies. The unwanted signals cause signal management problems in system
applications; constructively or destructively adding with desired signals. When out of
band, they can cause interference to other pieces of equipment.
VSWR
RL
RL
= +
−
−
−
1 10
1 10
20
20