Duplex Filter Module - Sailor RT2047 Technical Manual

2 CIRCUIT DESCRIPTION

2.8 DUPLEX FILTER MODULE 800

With a duplex filter, DF801, placed in the station it is possible to operate in full duplex mode with only one
antenna installed.
The duplex filter consists of 7 cavities, three in the Rx-section and four in the Tx-section.
The cavities in the Tx-section are stagger tuned. Two cavities (D-E) are suppressing the noise in the
receiving band 160.625 MHz - 162.025 MHz with Minimal insertion loss in the transmission band.
The function of the other two cavities (F-G) is to provide a band stop filter within the image frequency band
range of the duplex distance, 4.6 MHz: 151.425 MHz -152.825 MHz.
The cavities (A-B-C) in the Rx-section are stagger tuned. They are suppressing the transmitting
frequencies with Mid. insertion loss in the receiving band.
See the plot of duplex filters frequency response below.
NB: The duplex filter is adjusted with special measuring equipment and should be adjusted by S.P. Radio
A/S only.
TECHNICAL DATA FOR DUPLEX FILTER FOR VHF RT146 - RT2047.
75$160,77(5 G%
Band-stop attenuation -30
Band-stop attenuation -47
Insertion loss. Max 1.6
Return loss. Mid 1.7
5(&(,9(5 G%
Band-stop attenuation -60
Insertion loss. Max 1.5
dB
151.425 151.825 156.025
Insert. loss.
max. 1.6dB
-30dB
F G
-47dB
-60dB
B
A B C
24902
PAGE 2-28
RT2047 DSC - PART II
5$1*( 0+]
151.425 - 152.825
156.025 - 157.425
-
-
5$1*( 0+]
160.625 - 162.025
-
157.425 160.625 162.025
Frequency
(MHz)
Insert. loss.
max. 1.5dB
Tx-section Rx-section
E D
A C
D E F G
9543