Tuning The Filter Circuits Individually; 3.1 Steps For Tuning The Coils L1 And L2 - ABB ETL600 Instruction Manual

Revision:
A
3

Tuning the filter circuits individually

Once the Rx filter is programmed with jumpers for the required frequency band, its individual circuits must
be tuned with the help of the tuning adapters P4LM, P3LL and the HMI600 program. The tuning frequency
generated by the P4LT/P4LU, is fed into the Rx tuning adapter via the Tx tuning adapter using a coaxial
cable. Refer to chapter 5 "Test circuits", Figure 1 for the test circuit. The Rx tuning adapter provides
facilities for tuning the individual filter circuit stages.
The tuning adapter P4LM supports also older 3-stage filters. But as the filter has 2 stages, the L2 jumper
setting on the P4LM tuning adapter is not used. Use the L3 setting on the P4LM to tune the L2 coil on
the P4RX filter!
Note:

3.1 Steps for tuning the coils L1 and L2

Refer also to chapter 5 "Test circuits", Figure 1.
1. The Tx tuning adapter P3LL is inserted in place of the RF hybrid (P3LE).
2. P3LL is set as follows for the entire process:
• FUNCTION
• Position of S1
• Position of S2
• The Position of S3
• Position of LOAD
3. The P4LM is set as follows for tuning coil L1 of P4RX:
• The BNC connector OUT on P3LL is connected to the BNC connector IN of P4LM
• Position of S1
• Position of S2
• Position of S3 (select coil) : L1
• The BNC connector OUT of P4LM is connected to the input of the level meter (with 50 Ohm,
75 Ohm or high input impedance).
4. P4RX is plugged on top of P4LM.
5. If not already done, switch on the power of the ETL600, start up the HMI600 on the PC, log on to the
local ETL600 using equipment ID 0 and upload configuration and status of the equipment.
6. On the Equipment menu click Tuning & testing.
A warning message box appears, informing that the normal operation of the link will be interrupted.
7. Click OK to get the Tuning & testing dialog box.
8. Click Tune Rx RF filter to get the Tuning Rx RF filter dialog box.
9. Check if the correct filter center frequency f0 and bandwidth are shown.
10. Click Activate f1.
The adjuster screws in the coils L1 and L2 must be handled very carefully.
Never turn these screws beyond their stop position! The screws have
plastic M2 threads, which may be damaged easily! Only very little force is
needed to break the screws at the lower end of the adjustment range when
turning-in the screws.
To remove a damaged screw, first remove the top and bottom shield covers.
With a small screwdriver (1.5 mm), try to turn the remaining part of the adjuster
screw out of the coil (from the bottom side). Replace the adjuster screw with a
new one of the same type, and reassemble the shield covers before tuning.
Note:
The RF hybrid must not be plugged on top of P3LL.
: A
: L2
: FILTER
: Don't care
: Don't care
: NORM
: TUNE
Language: Page:
EN 3/7
1KHW001491-EN