I dont see 187Mhz in this picture … what was the Lo set at?
think about this for a moment …
145Mhz X 5 = 725Mhz, im not sure what you mean “at the bottom”
I made a video about using the LimeSDR on harmonics of the Lo (Lo is a square wave signal)
Im sure your seeing the same thing … Harmonic operation
You should place a bandpass filter on your Lime for the frequency span your interested in …
I have these in hand … one for 2m, 1.25 and 70cm
https://www.hobbypcb.com/products/uhf-vhf-radio/144mhz-band-pass-filter