After Sales
Technical Documentation
RAE/RAK–1N
RF
Page 3– 16
Amendment 1 04/97
2nd mixer (only in PCN)
The 2nd mixer is a single balanced passive diode mixer. The local signal
is balanced by a printed circuit transformer. The mixer down converts the
1st IF signal 313 MHz to 2nd IF signal 87 MHz.
Table 7. 2nd Mixer Specification (PCN)
Parameter Minimum Typical /
Nominal
Maximum Unit / Notes
1st IF frequency 313 MHz
LO frequency 400 MHz
2nd IF frequency 87 MHz
Conversion loss 5 6 7 dB
IIP3 2 5 dBm
LO – RF isolation 15.0 dB
LO power level 3 dBm
2nd IF amplifier (only in PCN)
The 2nd IF amplifier is realized using resistive feedback connection for
bipolar RF transistor.
Table 8. 2nd IF amplifier specification (PCN)
Parameter Minimum Typical /
Nominal
Maximum Unit / Notes
Operation frequency 87 MHz
Supply voltage 4.5 V
Current consumption 11 15 mA
Insertion gain 14 16 18 dB
Noise figure 2.5 3.0 dB
IIP3 –3 0 dBm
Input impedance matched to the mixer
Output impedance matched to IF filter
2nd IF filter (only in PCN)
The second IF filter (SAW) makes the part of the channel selectivity of the
receiver. It rejects adjacent channel signals (except the 2nd adjacent). It
also rejects blocking signals and the 3rd image frequency.
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