About using lms7002 in UHF band

Projects Lime Suite
1

Hello, I get some troubles when apply lms7002 to UHF band application and I need help.

RX_LO420M_S430M_REF40M.png640×454 6.75 KB
(1)
RX_LO420M_S430M_REF40M_NS.png640×454 7.23 KB
(2)
Above are two pictures that can illustrate what my troubles are. My test condition is LO-420MHz, Signal-430M-n90dBm, then IF-10MHz. The LO is generated from a ref which is 40MHz from SMA X18, and the signal is input to LNAL-A. From picture(1), the 10MHz IF signal is obvious, but it gets some unwanted companies. When I cut the input signal off, the unwanted signals still exist, and their magnitude remain the same, as in picture(2).
When I test in S band, LO-2G, Signal-2010M, I won’t get any problem like in UHF band. So what is the reason for f2, f3, and f4? Does LMS7002 really suitable for using in UHF band as declared in the datasheet?
You may blame this to the 40MHz ref, but I have to say that same problems occurred when using the onboard 30.72MHz TCXO. Below is a picture when LO ref is onboard 30.72MHz TCXO.
RX_LO420M_S430M_P90.png640×454 6.07 KB
(3)

2

Hello @wtswkz,

Could you provide more information, please:

  1. What board are you using? Assuming LimeSDR-USB 1v4, just want to doble check.
  2. Do you mean J18 connector on LimeSDR-USB board when saying:

?

3

The board I’m using is UNITE7002, which is looked like this:

IMG_20170609_164954.jpg2976×3968 2.23 MB

And SMA X18 is a ref clock input interface, used to synchronize the BB and the demo board, but I disabled the on board 30.72MHz TCXO by removing the power and some capacitors.

4

Ah, I see! Could you post a photo of a bottom view, please.

5

@Zack
Here is the bottom view of my board. And the R136 is removed in order to supply clock through X18 only.

IMG_20170610_205234_resized_20170610_085718338.jpg1488×1984 2 MB

6

Has anybody got any advice?