Bird Technologies Group 5PI613805 Manual De Usuario

REQUIRED EQUIPMENT
Due to the sensitivity of the adjustments, it is
strongly recommended that the proper equipment
be used when tuning the individual filters, other-
wise the filter should be sent to the factory or an
authorized representative for retuning. The follow-
ing equipment or it's equivalent is recommended in
order to properly perform the tuning adjustments.

1) IFR A-7550  Spectrum Analyzer / Tracking Gen-

erator combination.

2) Eagle Model RLB150BN3 Return Loss Bridge

(35 dB directivity).

3) Double shielded coaxial cable test leads

(RG142 B\U or RG223/U).

4) 50 Ohm load with at least -35 dB return loss

(1.10:1 VSWR).

5) Insulated metal blade tuning tool for adjusting

ceramic and/or piston variable capacitors.

Similar equipment from other manufacturers
should yield acceptable results.

TUNING PROCEDURE
The following general procedure assumes familiar-
ity with the use of a tracking generator.

1) Set the tracking generator to a center frequency

of the filter to be tuned. Set the tracking genera-
tor for 0 dBm output and a 10 dB/div scale.
Connect the equipment as shown in Figure 15
but leave the load port of the bridge uncon-
nected.

2) Set a 0 dB return loss reference. For the IFR  A-

7550 perform the following procedure:

a) Make sure that the unit is in "LIVE" mode
when performing step 7.

b)  From the Mode Menu, "STORE" the above
trace.

c)  Switch to the Display Menu and select
"REF".  The trace should appear at the 0  dB
level.

3) Connect the load port of the bridge to the filter

as shown in figure 15.

4) Adjust the cavity main tuning rod for maximum

return loss at the center frequency.

5) Set the tracking generator for the center fre-

quency of the filter and connect the test leads
as shown in Figure 16 but first temporarily con-
nect the leads together through a female barrel
connector and set a zero dB loss reference. On
the IFR A-7550 proceed as follows:

a)  Make sure that the unit is in "LIVE" mode when

performing step 2.

LOAD

REFLECTED

SOURCE

Analyzer
Input

Generate

Output

+30

+40

+20

+10

0

-10

-20

-30

-40

RLB - 150 Bridge

2" Square VHF

Pseudo-Bandpass Filter

Tracking Generator

Tune

Figure 15: Tuning the Pseudo-bandpass filter 

for maximum return loss.