RAT5 Manual version 1.2.0
RAT5 Information Manual version 1.2.0 © GW4GTE 2010
Page 7 of 29
Figure 2.1 RF and IF circuit
A low-side LO on 80m and a high-side LO on 160m places the image in relatively
quiet parts of the spectrum. The image frequency for 3615kHz is 2705kHz and the
image frequency for 1963kHz is 2873kHz. Compare with say a low-side LO on 160m
which would produce an image frequency in the MW broadcast band!
Figure 2.2 below is an actual plot of the bandpass filter on 80m showing the image
attenuation for a receive frequency of 3615kHz
Figure 2.2 Actual plot of RF bandpass filter on 80m
