Partyline: Connection of CCU Sony HCCU-100 to IF4W4 and MS702

Q: We are getting the MS-702 Clearcom party line system and we need to connect to CCU SONY, MODEL HCCU-100 with the IF4W4.
A: The IF4W4 is the interface between the 2w and 4w systems. To integrate the CCUs with the MS702:
1. The MS702 connects to the IF4W4 with a "MIC" cable using the XLR connectors.2. The IF4W4 connects to the Sony CCU HCCU-100 using the connector block, use this pinout:
CCU's DB-25:                                IF4W4's block connector: 
pin 1: ENG (R) (X) OUT                1 RX
pin 2: ENG (R) (Y) OUT                2 RX
pin 3: ENG (G)
pin 4: ENG (T) (X) IN                    4 TX
pin 5: ENG (T) (Y) IN                    5 TX
Once you have the whole PL system connected complete the "nulling" procedure on the IF4W4 to optimize the audio quality.
NULL ADJUSTMENT
The 'Null' control eliminates most of the receive signal from the transmit signal.
This control should be adjusted at installation and when the party-line cable configuration changes. For example, if the number of stations on the party line
or the length of the cable increases or decreases. R, L and C controls provide line-length compensation for adjusting the null.
These controls allow nulling for Clear-Com Party Line cable runs from 400 to 4000 feet (122m to 1219m).
To Adjust the Null
1. Connect a TS1 earphone or a four pin XLR headset (for monitoring the test tone provided with the interface) into the 'Null Monitor' connector on the
front panel.
2. Push the appropriate test null button for the channel to be nulled. A tone will be audible to help null the circuit.
Note: Depending on the installation the initial tone could be very loud so it is recommended the earphone or headset is not worn until the volume of
the tone has been reduced to a safe level.
3. Turn the R, L and C null control in either direction until a decrease in audible tone is observed. Continue to adjust the controls until the tone has
become inaudible.
4. Make fine adjustments by going back a couple of times over the R, L and C adjustments for a complete null.
If Complete Null Is Not Possible
1. Check for proper termination of the line.
Note: High frequency is controlled by line compensation. This part of the tone is distinguishable by its buzzing sound.