ANSI SCTE-120-2011 pdf download Test Method for Balance Ratio of 75-300 Ohm Matching Transformer
1.0 SCOPE AND DEFINITIONS
1.1 This test procedure provides a method for measuring the balance ratio of broadband radio frequency (RF) devices whose primary purpose is to provide an impedance and connector match between 75 , coaxial, type “F” and 300  twin-lead open screw connectorized devices.
1.2 Balance ratio is the measured signal difference between the device 300  twin-lead differential outputs when a 75 input is applied to the 75 ohm, coaxial, type “F” connector of the device.
1.3 This procedure uses the insertion loss measurements of the transformer differential outputs into a matched impedance to determine the balance ratio values.
2.0 NORMATIVE REFERENCES The following document contains provisions, which, through reference in this text, constitute provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreement based on this standard are encouraged to investigate the possibility of applying the most recent edition of the document listed below.
2.1 SCTE References
ANSI/SCTE 144 2007 Test procedure for Measuring Transmission and Reflection
3.0 EQUIPMENT
3.1 Network Analyzer (Agilent 8753E or equivalent)
3.2 Qty (2), 150  1%  leaded resistors.
3.3 Ground plane metal plate
3.4 2 clamps (to connect to ground plane)
3.5 Pin to F connector – F61 type
4.0 TEST SAMPLES
4.1 Obtain one sample of the matching transformer (device under test) to be tested.
4.2 If the device under test has a plastic outer sheath over the case, then remove the sheath so that a ground contact can be made with the device case.
4.3 Solder one lead of a 150  resistor to one of the transformer twin-leads. Then solder the lead of a second 150  resistor to the other transformer twin lead.
4.4 Solder the unconnected leads of the two resistors together and solder the leads to the pin of a Pin to F connector.
4.5 During preparation of test sample, visually inspect all solder connections on the 150  resistors for cold solder joints. Repair all cold solder joints prior to testing.
5.0 MEASUREMENT/TEST METHOD
5.1 Set up the network analyzer to measure insertion loss from 5 to 1002 MHz in accordance with ANSI/SCTE 144 2007.
5.2 Connect one end of the transformer test sample to port 1 of the network analyzer and the other end of the transformer test sample to port 2 of the network analyzer.
See Figure 1.
5.3 Connect the transformer test sample to the ground plane plate. See Figure 1.